Regis Petit's Website

Natural sciences

• C1. Climat change
• C2. Footprints of mammals and birds
• C3. Planetary motion
• C4. Constellations
• C8. Moon's influence

C1. Climat change

This chapter explores key aspects of climate change, including the role of the IPCC, the controversy surrounding the topic, greenhouse gases, individual and collective carbon footprints, and potential impacts and solutions to help us better understand how to address this global challenge.

1. Definition
2. IPCC
3. Controversy
4. Greenhouse gas
5. Carbon footprint
6. Impacts
7. Solutions
8. Sources

  

C1.1. Definition :

Climate change, also called "global warming", is the significant increase in the average temperature of the earth's surface since the beginning of the 20th century.
Be careful not to confuse "climate" and "weather". Weather refers to the weather over a short period (a day, a week). Climate refers to past and future time over long periods (year, century, millennium).

The graph above in left Figure shows that this increase (from 1900 to 2019) is unprecedented in the last 2000 years. The graph is a reconstruction including data from a wide variety of records such as tree rings, cave deposits, corals, etc. Added some relevant world events such as major volcanic eruptions, the Maunder Solar Minimum and historical dates of scientific discoveries. The oft-cited Medieval Warm Period and Little Ice Age are real phenomena, but small compared to recent changes [HAW].
Caption : Evolution of the global average annual temperature of the earth's surface from year 1 to 2019, relative to the pre-industrial reference (1850-1900) [HAW].

The graph above in right Figure shows that the decade 2011-2020 was 1.1 C warmer than the pre-industrial reference (1850-1900), with warming being greater on the continents (+1.6 C) than in above the oceans (+0.9 C) [TSP][GIE][MTE3].
Caption : Evolution of the global average annual temperature of the earth's surface from 1850 to 2020, relative to the pre-industrial reference (1850-1900) [MTE3]. The connected dots show the data year by year. The solid black curve is a rolling average of the annual totals over 11 years (average of years N-5 to N+5 for year N) making it possible to overcome the modulation due to the cycle of solar activity (11 years) [POI].

C1.2. IPCC :

The IPCC (Intergovernmental Panel on Climate Change) is a scientific body created in 1988, responsible for assessing the extent, causes and consequences of ongoing climate change.
The IPCC position confirms this warming and attributes it unequivocally to greenhouse gas (GHG) emissions of human origin, called "additional or additive or anthropogenic greenhouse effect" [WIK1].
A very broad scientific consensus endorses the IPCC position and agrees that solar irradiation is not the cause of climate change for two reasons [NAS1][NAS2] :
- Since the beginning of the 20th century, the average amount of solar energy received by the Earth has remained constant within 0.1 % [BLA] ;
- If the Sun were responsible for global warming, this warming would act in all layers of the atmosphere, from the surface to the upper atmosphere (stratosphere). However, the observations instead show warming at the surface and cooling in the stratosphere, which is consistent with the fact that the warming is caused by an accumulation of heat-trapping gases near the Earth's surface.

C1.3. Controversy :

Some people, called "climate skeptics", express denial of global warming and are divided into four main trends [WIK7] :
1. those who deny global warming ;
2. those who admit global warming but deny its human origin ;
3. those who admit global warming but deny its impacts ;
4. those who have no opinion on global warming but deny the scientific consensus on the topic (conspiracy theory).
The motivations are varied and lie essentially between two positions : doubt in good faith and doubt proclaimed out of interest [POI].

In the United States, in 2023, one in two inhabitants is climate skeptic [RFI] with motivations essentially oriented towards economic interest. Positions of denial, sometimes violent, are mainly held by "skeptical bloggers", supporters of conservative economic policies, industrialists opposed to the taxation of CO2 emissions and some groups financed by the tobacco and fossil fuel industries [ WIK7][RFI].
In the "top 3" of the most climate-sceptical countries, we find Saudi Arabia at the top, then come the United States and Australia, these countries being also three major producers of hydrocarbons (oil, gas and coal) [RFI].

In France, in 2022, 37 % of people consider themselves climate skeptics, including 8 % belonging to trend no. 1 [FJJ]. We can cite :

• Perplexity : some people doubt in good faith, often through ignorance of the facts or on the contrary by "drowning" in the multitude of facts.
• Invisibility : Unlike the weather, climate change is almost invisible because it occurs over very long periods of time. For people who have not suffered a major climatic disaster (hurricane, flood, etc.), denial is natural [MDS].
• Incongruity : for some people, mainly from the working classes, the "end of the month" often supplants the "end of the world" [ZEK].
• Disinformation : for some people, especially young people, social networks are the main, or even only, source of information [HIL]. Their algorithms are designed to favor content that generates the most emotions, or even the most toxicity or insults, which is particularly the case with climate skeptic discourse [LAP][FRI].
• Social conformism : In some communities where climate skepticism is the norm, people may adopt this stance to align with their social environment.
  
• Distrust : some people do not have confidence in intellectual elites (leaders, politicians, scientists, media, etc.).
• Intellectual avarice : for some people, denial makes them prefer information - even rare and controversial - that confirms their prejudice, rather than laborious analysis of the body of knowledge available on a topic [MDS]. They prefer to move towards what seems simple and accessible to them, even pseudo-scientific, rather than towards complex or scientific presentations [RIV].
• Intellectual dissonance : for some people, faced with information that contradicts their beliefs, maintaining the balance of their belief system is more vital than fighting climate change [ALL][RIV].
• Fear of truth : for some people, the prospect of an inevitable and final change in the climate is intolerable and therefore simply denied [MDS].
• Fear of losing : for others, denial is a safe haven, a form of protective instinct that allows you to preserve a way of life that you refuse to lose in today's consumer society [REP2].
• Fear of being nothing : for still others, denial is a way to assert one's social or political identity with the desire to be heard, listened to, recognized, admired, which can turn into "Mr. I know everything".
• Fear of conflict : for some people who have difficulty listening, denial is a reaction aimed not at dominating, but at avoiding being crushed, which can turn into "Mr. I am always right".
• Fear which hides others : the prospect of climate change relays other threats in large number (nuclear, atomic bomb, AIDS, mad cow, flood, etc.) which, instead of arousing generalized and lasting fear, end up fading after each media scoop. By crying wolf, no one believes it anymore. [MDS].

The controversy is therefore not scientific but societal [AFI].
When the doubt is in good faith, the controversy is rather passive, experienced in public opinion as a possible, probable and uncertain scenario, in a word a "discreet" and silent catastrophe [MDS].
When the doubt is proclaimed out of interest, the controversy is active, often polluted with verbal violence, particularly on the X platform (formerly Twitter).

C1.4. Greenhouse gas :

The Earth constantly receives energy from the sun in the form of visible light. 30 % is reflected by the atmosphere and the earth's surface, 20 % is absorbed by ozone and water vapor in the atmosphere, 50 % is absorbed by the earth's surface which heats up and emits infrared radiation from all the more intense as the surfaces are hot.
10 % of this radiation is emitted towards the universe, 90 % is absorbed by some gases called "greenhouse gases" and partly reradiated towards the surface, thereby slowing the loss of heat into space and causing global warming.
The Earth thus maintains an average temperature of +15 C by a natural balance between the energy of the sun absorbed and that re-emitted in the form of infrared radiation. Without these gases, the average temperature on Earth would be -18 C, and life as we know it would become impossible [NAS1][MTE1][DUF][WIK2][WIK3].
Since the beginning of the 20th century, man has considerably increased the quantity of greenhouse gases naturally present in the atmosphere, thus modifying the climatic balance through an additional greenhouse effect [MTE1].

These gases are essentially made up of the following elements [NAS1][WIK1][DUF][CDE][FRA1][ADT][CAR][BEN] :

• Water vapor (H2O), contained in the atmosphere and in the clouds, and contributing mainly of the natural greenhouse effect. Human activities have no direct influence on this water vapor, except on a local scale, such as near irrigated fields. Human activities, on the other hand, have an indirect influence via global warming which reinforces the global greenhouse effect by accentuating the evaporation of water (7 % more humidity per additional degree Celsius [GIE]).
• Carbon dioxide (CO2), released by natural processes (such as volcanic eruptions) and by human activities. It contributes 65 % to the additional greenhouse effect, mainly due to fossil fuels (60 % : extraction and combustion of coal, oil and natural gas) and deforestation (30 % : fewer trees to absorb CO2 through photosynthesis).
• Atmospheric methane (CH4), released by natural processes (such as the fermentation of plant matter in wetlands) and by human activities. It contributes 15 % to the additional greenhouse effect, mainly due to fossil fuels (30 % : leaks during production and transport of oil and natural gas), agriculture (40 % : gastric fermentation of ruminants, spreading of slurry, rice cultivation) and to municipal landfills (20 %).
• Nitrous oxide (N2O), released by natural processes (such as the decomposition of plants at their life end) and by human activities. It contributes 5 % to the additional greenhouse effect, mainly due to agriculture (spreading of nitrates of mineral origin (nitrogen fertilizers) and organic (slurry and manure)).
• Tropospheric ozone (O3), released by chemical reaction between carbon compounds including methane and nitrous oxide, therefore indirectly by natural processes and by human activities. It contributes 10 % to the additional greenhouse effect.
• Chlorofluorocarbons (CFCs), released exclusively by human activities (pesticides, cosmetics, aerosols, etc.). They contribute 5 % to the additional greenhouse effect and are the cause of the "hole" in the stratospheric (at high altitudes) ozone layer. They have been banned since 1987 via the Montreal Protocol. Substitute products (HFCs) are not harmful, but contribute just as much to the additional greenhouse effect.

In summary, according to these figures, global warming of human origin (additional greenhouse effect) is mainly due to fossil fuels (47 %), agriculture (25 %) and deforestation (20 %).

In France, the transport sector constitutes the largest source of greenhouse gas emissions, accounting for 30 % of national emissions.
Over the entire life cycle of vehicles (extraction and processing of raw materials, manufacturing, transportation and use of the vehicle), these emissions are attributable as follows : passenger cars (53 %), heavy goods vehicles (27 %), utility vehicles light (15 %), air transport (3 %) and other modes of transport (2 % : two-wheelers, rail and maritime) [GRE].

C1.5. Carbon footprint :

The carbon footprint (or GHG balance) of a product, a person, a company, a sector of activity or a territory is a measure of the cumulative quantity of all greenhouse gas emissions that can be attributed to it. This measure can be evaluated according to two conventions :
    - either in direct emissions due to the use of energy by the final consumer ;
    - either in life cycle analysis taking into account emissions due to the use of energy but also indirect emissions due to all upstream energy transformations (research and development, production, transport, distribution ), or even downstream (recycling, dismantling) [WIK4].
Example of carbon footprint for different modes of transport (in CO2 equivalent per passenger over 100 km) : plane (20 kg), motorcycle (19 kg), gasoline car (15 kg), diesel car (14 kg), electric car (10 kg), coach (3 kg), TGV (0.2 kg) [SEL].
For a greenhouse gas, its contribution to the greenhouse effect is measured by its Global Warming Potential (GWP) defined as the radiative forcing (i.e. the radiative power that the gas returns to the ground), accumulated over a reference period of 100 years and measured relative to the same mass of CO2.
The GWP is 1 for CO2 ; 8 for water vapor ; 30 for CH4 ; 300 for N2O ; 700 to 15,000 for CFC, HFC and PFC ; 17,000 for the NF3 ; 25,000 for SF6.
The carbon footprint of gas is then expressed in grams of CO2 equivalent per kilowatt-hour (gCO2eq/kWh) corresponding to the product of the mass of gas (mog) by its Global Warming Potential (GWP).
The carbon footprint of gas is sometimes also expressed by a Carbon Equivalent (CE) which only measures the mass of carbon (C) contained in the CO2 emitted. We then have the relationship : CE = 0.2727 x mog x PRG

The Bilan Carbone is a method of calculating the carbon footprint according to three distinct scopes of emissions (direct induced by the combustion of fossil fuels, indirect induced by energy consumption, indirect other).
It takes into account the six greenhouse gases designated by the Kyoto Protocol (CO2, CH4, N2O, hydrofluorocarbons (HFC), perfluorocarbons (PFC) and sulfur hexafluoride (SF6)), as well as trifluoride nitrogen (NF3), and water vapor in the case of air transport [WIK5].

The ecological footprint (or environmental footprint) covers a broader spectrum and consists of estimating the quantity of land and water necessary for an individual or population to meet its needs without depleting natural resources or disrupting the ecosystem.
More than half of the French ecological footprint is due to the carbon footprint [WIK6].

C1.6. Impacts :

The main effect of global warming is [NAT1] :

• to evaporate more water contained in the oceans and soils, which makes the air globally warmer and more humid, leading to an increase in storms and heavy rains but also, paradoxically, more intense periods of drought [NAT2].
  In Metropolitan France, since 1961, there has been :
      - an increase in the number of hot days (5 days of summer temperature (T > 25 C) per decade) [MEF1][BLA] ;
      - a decrease in the number days with frost (4 days per decade) [BLA] ;
      - a decrease in the number days with snowy ground (7 days per decade) [MEF1][BLA] ;
      - a great stability in the average annual cumulative precipitation (935 mm/year) but with regional disparities : significant increase in the northern half (particularly the North-East), significant decrease in the southern half (particularly the South-East and the Mediterranean rim) [MEF1][SEN] ;
      - an increase in the intensity and frequency of heavy daily rains on the Mediterranean rim [MEF1][ONE] ;
      - an increase in the intensity of storms associated with a decrease in their frequency, in the Mediterranean regions [MEF2].
  Warning : Some articles on the Internet present different figures or reverse disparities, and without citing their sources.
• to warm the water contained in the oceans and glaciers, which leads to a rise in sea level due to the thermal expansion of waters and the melting of mountain glaciers and polar ice caps. Since the beginning of the 20th century, ocean water has been rising at a rate of approximately 2 mm per year (and 4 mm per year over the last decade) [WIK8][MTE2].
• to warm urban buildings whose heat is reflected in the basements, causing the contraction of some materials, such as soft clay, and the expansion of others, such as limestone. As urban basements heat up more and more, they are deformed, even cracked, and affect the sustainability of city infrastructures [REP].
• to warm frozen soils. The Far North will particularly suffer from warming : all infrastructure is based on frozen, and therefore rigid, soil, the melting of which will completely destroy its cohesion. We are already seeing collapses of infrastructure and homes [POI].
• to displace populations by exposing them to a risk of poverty, rain floods which can wash away shanty towns, heat which can make it difficult to work in the open air, and lack of water which can harm crops [NAT1].

By the end of the century, if GHG emissions follow their current trajectory without additional climate policy and with high population growth (IPCC SSP3-7.0 scenario), warming will be +4 C with sea levels rising 1 m relative to the pre-industrial reference (1850-1900) [MTE4].
In this probable scenario, particularly if States engage in regional or global conflicts to the detriment of international climate policies, the IPCC identifies several key risks for Europe, which directly concern France [RCA1] :

• Heat waves : the number of people who will die from heat will reach 5000 per year in France (compared to 1500 currently). Heat waves will also have irreversible consequences on ecosystems, particularly on Mediterranean biodiversity : disappearance of plants and species, destruction of sea meadows [RCA1].
• Decreases in agricultural yield : a direct consequence of the previous risk, but also of drought and rainfall variability, crop losses will continue to increase, endangering the livelihoods of producers [RCA1].
• Water shortages : over the past 20 years, land water storage has decreased by one centimeter per year [NAT2]. This agricultural and hydrological drought is mainly due to the more rapid evaporation of water present in the soil and the evacuation of surface water during heavy rains before it has time to fill the groundwater tables [FRA2].
  Added to this is water pollution, particularly at the agricultural level by excess nitrates and pesticides, which compromises the quantity and quality of available water [IDV][BEN].
  Added to this are our increasingly water-intensive consumption patterns at the industrial and domestic level [AMB].
  The risk of Water shortages particularly concerns the south of France, with more than a third of the population in this area potentially lacking water during part of the year [RCA1].
• Coastal flooding : France is one of the European countries most threatened by coastal flooding [RCA1], in particular the Mediterranean coast where many cities, heritage sites and natural wetlands are very close to the coast.
• Desertification : erosion of the surface layer of soil affects cultivated land and natural environments. It is due to difficult climatic conditions (low rainfall, strong winds, excessive heat, etc.) and fragile soils (thin or sandy soils), as well as inappropriate human activities such as arson, overgrazing, overexploitation agricultural soils, deforestation, unsuitable irrigation practices, excessive soil concreting, etc. [LAR].
  Europe is increasingly affected by desertification due to human activities [CCE]. Forests around the Mediterranean, including southeastern France, could disappear in favor of semi-desert areas like the steppes [ROY].
• Particular impacts in Overseas Territories : extreme events (heat waves, cyclones, etc.) will be more and more frequent and intense. Rising water levels will seriously threaten habitats. Ecosystems will also be in great danger with coral dieback [RCA1].

C1.7. Solutions :

The fight against climate change relies on two levers :

• Reduce greenhouse gas emissions to contain global warming. The international community has set itself the objective of limiting the rise in temperatures to 2 C : this is mitigation [MTE2].
• Adapting society to the impacts of global warming : this is adaptation [MTE2]. In Europe, despite the need to act immediately, adaptation is very insufficient. The obstacles cited by the IPCC include a lack of political will, weak commitment from citizens and the private sector as well as a "weak sense of urgency" [RCA1].

The recommended solutions are as follows [RCA2] [MTE2][MTE3] :

• Energy : get out of fossil fuels and invest in renewable energies, particularly solar and wind energy.
• Sobriety : move towards a deconsumption society by reducing energy demand, but also for materials, land, water, etc., while ensuring the well-being of people. Examples of actions for a more sober society :
      - Give priority to car-free mobility, favoring walking and cycling for example;
      - Favor public transport;
      - Promote electric vehicles;
      - Reduce air travel (especially long-haul flights).
• Adaptation : deploy measures to adapt to changes already underway and anticipate those to come. For example, diversifying agricultural crops, greening cities to cope with heat waves, developing alternative activities to alpine skiing in mountain resorts.
• International cooperation in finance and technology.

C1.8. Sources relating to climat change :

[ADT] Académie des technologies, Le méthane - d'où vient-il et quel est son impact sur le climat ?.
[AFI] Afis Science, Le "climato-scepticisme" : un concept fourre-tout.
[ALL] Vanessa Allnutt, Les climatosceptiques contre la science.
[AMB] Valentine Ambert, Va-t-on manquer d'eau ?, Youmatter.
[BEN] Marc Benoît, Pollutions agricoles, CNRS Editions.
[BLA] Guillaume Blanc, Le réchauffement climatique.
[CAR] Carbone4, L'ozone des basses altitudes, une épée à double tranchant.
[CCE] Cour des Comptes Européenne, Lutte contre la désertification dans l'UE : le phénomène s'aggravant, de nouvelles mesures s'imposent.
[CDE] CDE - Connaissance des Energies, Gaz à effet de serre : d'où proviennent les émissions de méthane ?.
[DEL] Céline Deluzarche, Pourquoi manque-t-on de plus en plus d'eau alors que les pluies augmentent ?, Futura.
[DUF] Jean-Louis Dufresne, L'effet de serre, Planet Terre.
[FJJ] Fondation Jean Jaurès, Climatoscepticisme : Le nouvel horizon du populisme français.
[FRA1] Franceinfo, COP26 : on vous explique ce qu'est le méthane, l'autre gaz à effet de serre qui réchauffe le climat.
[FRA2] Franceinfo, Changement climatique : on vous explique pourquoi sécheresse et inondations sont parfois liées.
[FRI] France Inter, Algorithmes : les meilleurs amis des climatosceptiques.
[GIE] GIEC, Synthèse du rapport AR6 du GIEC publié le 27/03/2023.
[GRE] Greenly, Les transports, premier secteur émetteur en France.
[HIL] David Hiler, Réchauffement climatique : comprendre ceux qui n'y croient pas, Le Temps.
[IDV] idverde, Comment réduire les risques de pénurie d'eau ?.
[LAP] Pascal Lapointe, Les réseaux sociaux favorisent le discours climatosceptique ? Vrai, Agence Science-Presse.
[LAR] Larousse, Désertification.
[MDS] Martin de La Soudière, Le changement climatique, une "grande peur" collective ?.
[MEF1] Meteo France, Climat HD.
[MEF2] Meteo France, Tempêtes en France métropolitaine.
[MTE1] Ministère de la transition écologique et de la cohésion des territoires, Pourquoi la Terre chauffe ? 14 septembre 2018.
[MTE2] Ministère de la transition écologique et de la cohésion des territoires, Dossier de presse - 1er Plan national d'adaptation au changement climatique, 20 juillet 2011.
[MTE3] Ministère de la transition écologique et de la cohésion des territoires, Observations du changement climatique.
[MTE4] Chiffres clés du climat - France, Europe et Monde (décembre 2022).
[NAS1] NASA, Les causes du changement climatique.
[NAS2] NASA, Le Soleil est-il à l'origine du réchauffement climatique ?.
[NAT1] Nations Unis, Causes du changement climatique.
[NAT2] Nations Unis, L'eau - au coeur de la crise climatique.
[ONE] ONERC, Les évènements météorologiques extrêmes dans un contexte de changement climatique.
[POI] Jean Poitou, Climat : distinguer le vrai du faux, Progressistes.
[RCA1] Réseau Climat Action France, 6e rapport du GIEC : quelles sont les conséquences réelles du changement climatique ? 28-02-2022.
[RCA2] Réseau Climat Action France, Synthèse du 6e rapport du GIEC : l'urgence climatique est là, les solutions aussi, 20-03-2023.
[RCA3] Réseau Climat Action France, 6e rapport du GIEC : quelles solutions face au changement climatique ? 04-04-2022.
[REP1] Reporterre, Le réchauffement des sous-sols, une "menace silencieuse".
[REP2] Reporterre, Déni de réalité : pourquoi le climatoscepticisme progresse.
[RFI] RFI, Pourquoi y a-t-il encore autant de climatosceptiques aux Etats-Unis et dans le monde ?.
[RIV] Johan Rivalland, La Démocratie des crédules - Critique du dernier livre de Gérald Bronner.
[ROY] Florentin Roy, Les forêts en Méditerranée vont-elles disparaître ?, Youmatter.
[SEL] Selectra, Empreinte Carbone : calcul, définition et conseils de réduction.
[SEN] Sénat, Adapter la France aux dérèglements climatiques à l'horizon 2050 : urgence déclarée.
[TSP] The Shift Project, Climat : synthèse vulgarisée du 6ème rapport du GIEC (mars 2023).
[WIK1] Wikipedia, Gaz à effet de serre.
[WIK2] Wikipedia, Effet de serre.
[WIK3] Wikipedia, Changement climatique.
[WIK4] Wikipedia, Empreinte carbone.
[WIK5] Wikipedia, Bilan carbone.
[WIK6] Wikipedia, Empreinte écologique.
[WIK7] Wikipedia, Déni du réchauffement climatique.
[WIK8] Wikipedia, Elévation du niveau de la mer.
[ZEK] Marie Zekri, 37 % des Français se considèrent climato-sceptiques, National Geographic.

C2. Footprints of mammals and birds

Footprints printed on the ground or in the snow allow most mammals and birds to be identified.
For birds, the identification method is based on each Isolated footprint, a bird being able to only walk or hop on the ground.
For mammals, the identification relies on the joint use of three different methods based on the following observations :
- Isolated footprint,
- Succession of footprints, giving the movement pattern of the animal,
- Droopings of the animal.

1. Isolated footprint
2. Succession of footprints
3. Droppings

   

C2.1. Isolated footprint

Mammal footprints are all Hand type (with 3, 4 or 5 fingers per paw, excluding palm), Pads type (with 4 or 5 digital pads per paw, excluding palm) or Hooves type (with 1, 2, 3 or 4 fingers per paw, excluding foot sole).
Bird footprints are all Hand type comprising, with some exceptions, 3 fingers per paw supplemented by a fourth opposite finger (thumb) which may be reduced or completely absent.
The 4 slides below present a method of identifying mammals and birds from their isolated footprints.

Sources :
(empreintes des mammifères) Ma Chasse, Les mammifères.
(empreintes des mammifères) France Nature Environnement - Haute-Savoie, Les empreintes.
(empreintes des mammifères) Gilles Christophe, FRAPNA, Les mammifères de Rhône-Alpes- les empreintes.
(empreintes des mammifères) Salamandre, Empreinte de mammifères.
(empreintes des oiseaux) Ma Chasse, Les oiseaux.
(oiseaux) Zadi Bridge, Combien les oiseaux ont-ils de doigts ?.
(ongulés) Puverel Camille, Leprince Julie, Atlas des mammifères de Rhône-Alpes - Les ongulés.

C2.2. Succession of footprints

The slide below presents a method of identifying quadrupedal mammals from their movement pattern.
The legs are marked as follows : 1 left front leg, 2 right front leg, 3 left hind leg, 4 right hind leg, P projection in the air (hanging time).
The main movement patterns are as follows :

• Walk : 4-stroke movement which responds to a double principle : the movement of a front leg is followed by that of the hind leg located diagonally ; the movement of a hind leg is followed by that of the front leg located on the same side. The walker therefore advances the left front leg (n 1), then the right hind leg (n 4) which is printed just behind or on the trace of the front paw, then the right front leg (n 2), then the left hind leg (n 3). The formula for displacement is : 1 4 2 3 (see photo below and slide below).
  
• Trot : 2-stoke movement, each followed by a projection. Apart from the addition of the two projections, trotting is almost identical to walking, the crossed movement of the front leg and the hind leg no longer being successive but simultaneous. The formula for displacement is : 14 P 23 P (see photo below and slide below).
  
• Back up : 2-stroke retrograde movement. Backing up is walking backwards using diagonal strides, which is almost identical to trotting without the two projections. The displacement formula is : 14 23 (see photo below of Blog Equitation Nord, and slide below).
       
• Amble : 2-step movement, each followed by a projection when the movement is fast. The ambler swings its body from left to right, moving its legs together on the same side. The hind paw prints next to the trace of the front paw. Apart from the addition of the two possible projections, ambling is almost identical to walking, the movement on the same side of the hind leg and the front leg no longer being successive but simultaneous. The formula for displacement is : 31 (P) 42 (P) (see photo below and slide below).
  
• Gallop (left or right) : 3-step movement with additional time of hanging. The galloper advances the hind leg first, then together the two diagonal legs which are not part of it, then the front leg diagonally opposite to the one which landed first, then throws itself into the air. Apart from the addition of the projection, galloping is almost identical to walking, the movement of these two diagonal legs no longer being successive but simultaneous. The formula for displacement is (see slide below) : 4 23 1 P for a gallop left (see photo n 1 below) and 3 14 2 P for a gallop right (see photo n 2 below).
  
  
• Grouped leap : 2-step movement with additional time of hanging. The leaper has hind legs that are generally larger than the front legs. Just after the leap, the leaper places its front paws together on the ground, then its hind paws which are printed on the front paws tracks, then leaps into the air. The formula for displacement is : 12 34 P (see photos below from video Youtube "CHEVREUIL", and slide below).
     
• Ungrouped leap : 2-step movement with additional time of hanging. The leaper has an elongated body with generally short legs. Just after the leap, the leaper places its front paws on the ground (together for the squirrel or one in front of the other for the hare), then passes its hind paws on each side of the body which are printed in front of the front paws tracks, then leaps into the air. The formula for displacement is : 12 34 P or 1 2 34 P (see photos below from Pilon Michel, and slide below).
     
  

Nota :
- Walking exists in all quadrupedal mammals. For some, it is sometimes slow and infrequent (that of the squirrel for example).
- For the first five movement patterns (Walk, Trot, Back up, Amble, Gallop), the order of legs movement is always the same : 1 4 2 3, with some legs sometimes being moved together, being part of the same diagonal or the same side.

Sources :
(amble) Wikipedia, Amble.
(amble et galop du cheval) Dictionnaire visuel - Allures du cheval.
(bond du renard, lièvre et écureuil) Espaces, Suivre à la trace.
(bond de la belette) J'ai suivi une petite belette sauvage (Youtube, 5:45).
(bond de l'écureuil) Pilon Michel, Forum Image et Nature.
(démarche des mammifères) Les Chasseurs à l'Arc de la Réunion, LES TRACES D'ANIMAUX DANS LA FORET (EUROPE).
(démarche des mammifères) Couzi Laurent, Planche N 1 intitulée "Empreintes animales" du livre Phénomènes, Juzeau C. , Rébulard M., Caradec C., Editions du Chêne, 2023.
(marche, amble et bonds) La Presse+, Jouer au détective dans la neige.
(marche, amble et bonds) Fédération Canadienne de la Faune, A la découverte du monde du pistage d'animaux.
(pas, trot et galop du cheval) Le Monde des Chevaux, Les allures.
(pas, trot et galop du cheval) Wikipedia, Allure (équitation).
(pas, trot et galop du cheval) Lenoble du Teil Jules, Etude sur la locomotion du cheval et des quadrupèdes en général, 1873, LENOBLE_ETUDE_SUR_LA_LOCOMOTION_1873.pdf (accompagné d'un atlas de 23 planches).
(reculer du cheval) Blog Equitation Nord, Hippologie : les allures.
(reculer du cheval) Devos Emma, chevalogie.free.fr, Le reculer.
(vidéos du cheval) Hippologie.fr, Les allures du cheval.
(vidéo du trot du cerf) Cerf qui court et au trot (Youtube, 4:11).
(vidéo du galop du cheval) galop au ralenti (Youtube, 1:08).
(vidéo du galop du chameau) Course de chameaux en Egypte (Youtube, 1:54).
(vidéo du bond du chevreuil) CHEVREUIL/Sauts et Course ! BRUITX (Youtube, 2:00).

C2.3. Droppings

The slide below presents a method of identifying mammals from the shape and texture of their droppings.
Size is another clue. It is generally proportional to the length of the animal's rectum, therefore also to the size of the animal.
Color is also another clue, but it depends on the freshness of the deposit and the ingestion of some foods. For examples :
- Fresh mouse droppings are black and turn brown after about 24 hours.
- The color of hedgehog droppings can vary from black to brown to different shades of gray, depending on its diet which mainly consists of insects, molluscs and small vertebrates.
- A dog that eats too many bones or industrial food containing too much animal flour will produce white droppings. In the sun, the white color will be even more pronounced because the water contained in the droppings evaporates, bringing out the calcium.
- A wolf that swallows the bones of its prey will produce white droppings.

The deposit of droppings is generally done on the paths taken by the animal. For carnivores, in addition to the natural evacuation function, the deposit corresponds to the visual and odorous marking of the territory, often at crossroads between paths.

Sources :
(détail) Gilles Christophe, FRAPNA, Les mammifères de Rhône-Alpes - Les fèces.
(détail) Martin Alexis, Petit guide illustré des crottes de mammifères.
(détail) Salamandre, Crottes de mammifères.
(général) Espace pour la vie Montréal, Des crottes qui en ont long à dire.
(images) Lahaye Romain, Atlas préliminaire des Mammifères sauvages de Bourgogne.
(tableau) France Nature Environnement - Haute-Savoie, Les crottes.
(tableau) Carbala, Espace outil pédagogique.

C3. Planetary motion

The planetary motion is directly derived from Newton's law of universal gravitation, which governs the behavior of a system of two bodies in gravitational interaction.
Formulation : Two point bodies M and m separated by a distance d between their centers attract each other with a force F whose intensity is given by the formula :
(R1) F = G M m / d²
where G is the universal gravitational constant (G = 6.67408 10^-11 kg^-1.m³.s^-2).
This force is attractive and acts along the straight line connecting the centers of the two bodies.

In the case of an isolated system, the law of universal gravitation induces the following laws, called "corrected Kepler's laws", which may be slightly disturbed in a real context by gravitational interactions with other bodies.

1. Galilean reference frame
2. Flatness of trajectories
3. Elliptical orbits
4. Area law
5. Period law
6. Conservation of mechanical energy
7. Sources

Figures 1 and 2 : Motion of two bodies A and B of very different masses (Figure 1) and of the same mass (Figure 2) under the gravitation effect [SES].
Figure 3 : Link between trajectories (ellipse A/C, ellipse B/C, relative ellipses A/B and B/A) with C = barycenter of the system and d = distance between bodies A and B

1. Galilean reference frame :

Formulation :
- We consider an isolated system of two bodies A and B in gravitational interaction (two-body problem).
- The reference frame centered at the center of mass C (barycenter) of the system is an inertial (or Galilean) reference frame.

2. Flatness of trajectories :

Formulation : The trajectories of the two bodies are located in the same orbital plane, perpendicular to the kinetic momentum vector of the system of the two bodies, calculated relative to the barycenter of the system.
Associated Kepler's law : The orbits of the planets are planar.

3. Elliptical orbits :

Formulation :
- Each body in the system describes an elliptical orbit with one focus being the barycenter of the two-body system.
- In the case of the Sun-planet system, since the Sun is much more massive, the barycenter is very close to the center of the Sun. Consequently, the planet appears to orbit the Sun when in reality the Sun also describes a small ellipse around this barycenter (see Figure 1 above).
- This small ellipse can become significant in systems where the mass difference is less important such as in a binary star system (see Figure 2 above).
- The semi-major axes of each ellipse are aligned. Thus, when one of the bodies reaches its pericenter (the point of the orbit closest to the focus), the other body is also at its pericenter.
Associated Kepler's law : The planets describe elliptical orbits with the Sun at one of the foci.
Elliptical orbit equation (in polar coordinates) : r = p/(1 + e cos[θ])
with :
   θ r = distance from the body to the occupied focus of the ellipse
   p = focal parameter
   e = eccentricity
   θ = polar angle
We have the relations :
(R29)
a = p/(1 - e²)
b = p/(1 - e²)^1/2
c = (a² - b²)^1/2 = e a
b² = a²(1 - e²)
p = b²/a
S = π a b
with :
   a = semi-major axis
   b = semi-minor axis
   c = semi-focal distance (or distance between the ellipse center and one of the foci)
   S = area

4. Area law :

Formulation : The radius vector connecting a body to the occupied focus of the ellipse sweeps out equal areas in equal times.
Associated Kepler's law : The radius vector connecting the Sun to a planet sweeps out equal areas in equal times.
Expression of the area law : dS/dt = (1/2) r² dθ/dt = constant = (1/2) σ/m
with :
   S = area swept out by the radius vector in the orbital plane
   r = distance of the body from the occupied focus of the ellipse
   θ = polar angle
   t = time
   σ = angular momentum of the body relative to the occupied focus
   m = mass of the body

5. Period law :

Formulation : The orbital period of each body is given by the formula :
(R70) T²/a³ = 4 π² / k
with :
   T = orbital period
   a = semi-major axis of the ellipse
   m and M = respective masses of bodies A and B
   Case of body A rotating around body B : k = k_A/B = G (m + M)
   Case of body A rotating around the barycenter C of the system : k = k_A = G (M³ / (m + M)²)
   Case of body B rotating around the barycenter C of the system : k = k_B = G (m³ / (M + m)²)
Associated Kepler's law : The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.
Invariance of orbital period : Given the relation (R89), T depends only on the mechanical energy E_mec of the system.

6. Conservation of mechanical energy :

Formulation : The mechanical energy of the system, the sum of the kinetic energy of the relative motion between bodies and the potential energy of interaction, is conserved over time.
Expression of the mechanical energy E_mec as a function of the parameters p and e of the ellipse :
(R80) E_mec = (1/2) (G m M / p) (e² - 1)
with :
   m and M = respective masses of bodies A and B
   p = focal parameter of the relative ellipse in the motion of A relative to B, or of B relative to A
   p = p_A/B = p_B/A = p_A/C (1 + m_A/m_B) = p_A/C + p_B/C
   e = eccentricity of the ellipse
This energy is always negative for an ellipse (|e| < 1).

7. Sources relating to planetary motion :

[CHA] ChatGPT, le moteur d'Intelligence Artificielle développé par OpenAI.
[CHE] Jonathan Chenal, Introduction à l'astronomie de position
[FEM1] FEMTO - Mécanique, Problème à deux corps
[FEM2] FEMTO - Mécanique, Forces centrales
[PER] Perplexity, le moteur d'Intelligence Artificielle développé par Perplexity AI.
[PST] Gravitation : le problème des deux corps avec PSTricks - partie 1
[SES] SESP, Mouvement de deux corps sous l'effet de la gravitation
[SOR] Joël Sornette, Le problème à deux corps - Mouvements à force centrale
[VIE] Alain Vienne, Eléments d'astronomie fondamentale

C4. Constellations

Constellations, apparent groupings of stars forming imaginary figures in the sky, have fascinated humanity for millennia.
Today, 88 official constellations are used to map the sky. Some, such as The Little Bear or Cassiopeia, are visible all year round, while others, such as The Swan in summer or Orion in winter, are only revealed in certain seasons.
The zodiacal constellations, crossed by the Sun during the year, are part of these 88 official ones and play a special role in astrology.
Observing the sky also reveals remarkable stars, such as Sirius or Vega, real landmarks in the celestial vault. To make the most of them, it is then important to follow certain practical observation tips.

1. General information
2. List of constellations
3. Constellations visible all year round
4. Summer seasonal constellations
5. Winter seasonal constellations
6. Other constellations
7. Zodiacal constellations
8. Tips for good observation
9. Coordinates, color and magnitude of a celestial body
10. Sources

C4.1. General information [CHA][PER] :

Definitions :
- A constellation is an apparent grouping of stars in the night sky as seen from Earth.
- A circumpolar constellation is one that, for an observer at a given latitude (north or south), remains visible year-round.
- A seasonal constellation is a non-circumpolar constellation, therefore visible only during or around a given season, and absent from the night sky the rest of the year.
- The ecliptic is the plane of the Earth's orbit around the Sun or, as seen from Earth, the circle traced by the Sun on the celestial vault over the course of a year.
- The horizon is the horizontal circular line where the sky and the Earth (or the sea) appear to meet.
- The zenith is the point in the sky located exactly vertically above the observer's head.
- The North Celestial Pole is the point in the sky located above the northern horizon, at a height equal to the observer's latitude. For Paris (approximately 49 north latitude), on a rotating disk sky map, this point appears halfway between the center of the disk (zenith) and its northern edge (northern horizon). To use the disc correctly, it must be held above the head and the northern edge of the disc must be oriented towards geographic north, using a compass for example.
- Warning : On a sky map, the east and west directions are reversed compared to a traditional map, in order to correspond to the viewpoint of the observer holding their map towards the sky. Turning a map over (putting it upside down) while keeping north in front of you effectively reverses right and left.
- The North Star (Polaris) is an excellent representative of the celestial north pole, through which the Earth's own rotational axis passes. The angular difference between these two points (approximately 0 38' in 2025) is in fact imperceptible to the naked eye because the north celestial pole is only an abstract point in the sky, located very close to Polaris.

Movement and position of the constellations :
- The movement of the constellations is as follows : Due to the daily rotation of the Earth on its axis, all the constellations visible from the northern hemisphere describe a circle around Polaris in 24 hours, counterclockwise, but only the circumpolar ones remain visible at all times. The seasonal ones pass below the horizon during their rotation, rising in the east and setting in the west each day.
- The relative geometric position between constellations, as well as between stars in the same constellation, does not change significantly during the Earth's daily rotation (diurnal motion) or during its annual revolution around the Sun (seasonal motion). This is explained by the very great distance between Earth and the stars in these constellations. Only the portion of the sky visible from a given location on Earth at a given time changes.
- The "open hand" is a good guide to measuring the distance between two points in the sky : Hold your hand at arm's length, fingers spread, and consider the width extending from the tip of your thumb to the tip of your little finger. This width corresponds to an angular difference of about 20 measured from the observer.

Stars, planets, the Moon, artificial satellites, aircraft, shooting stars, star cluster :
- Stars twinkle. This phenomenon is due to the turbulence of the Earth's atmosphere that disrupts the light coming from these very distant point sources.
- The planets of the solar system, on the other hand, do not twinkle or twinkle very little. They are in fact much closer to Earth and appear to the naked eye as points of light just like stars, and to the telescope as small luminous discs.
- The planets and the Moon only pass through the constellations of the astronomical zodiac, never the circumpolar constellations or the non-zodiacal seasonal constellations. Indeed, the planets and the Moon always remain very close to the ecliptic, while these constellations are located far from the ecliptic (circumpolar ones around the celestial pole, north or south, non-zodiacal seasonal ones elsewhere in the sky).
- The planets and the Moon are not circumpolar : They rise and set every day, while gradually moving relative to the distant stars in the background sky. The Moon moves about 13 eastward each day relative to these stars and therefore takes 27.3 days to complete one apparent orbit around the North Star. The planets move much more slowly and take several years, depending on the planet, to complete one orbit.
- The Moon is absent from the night sky during nights close to the new moon at certain times (see Tips for good observation), which allows optimal observation of the constellations.
- Artificial satellites in low Earth orbit appear as a white, non-blinking point of light that crosses the sky from west to east in a few minutes.
- Aircraft flying at high altitudes appear as a flashing white point of light (anti-collision strobe light), which moves more slowly than artificial satellites. At medium or low altitudes, aircraft are distinguished by several fixed colored points of light (position lights), in addition to the flashing white point, all of which can appear separate or merged depending on the distance from the observer.
- Shooting stars (or meteors) are luminous trails visible for one to two seconds. They come from dust clouds left by comets or asteroids. Each year, the Earth crosses the orbit of these clouds, causing their dust to burn up upon contact with the Earth's atmosphere. On average, 5 to 10 shooting stars are observed per hour, and up to 50 to 100 during peak activity of these meteorite clouds, particularly between mid-July and mid-August in the constellation of Perseus, and early to mid-December in the constellation of Gemini.
- A star cluster is a local grouping of stars bound together by gravity, born from the same region of gas and dust within the same galaxy. Seen from Earth, it appears projected into a constellation.

Brightest objects :
The brightest natural objects in Earth's night sky, visible from the Northern Hemisphere, are as follows, in descending order of brightness :

• The Moon (apparent magnitude M = -12.7 in full moon)
• Venus, called "the Shepherd's Star" (maximum M = -4.6, low height in sky, visible for 7 to 8 months in the evening since August 2024 and in the morning since April 2025, then every 19 months for each of these periods)
• Jupiter (maximum M = -2.7, medium height in sky, visible every year from October to May)
• Mars (maximum M = -2.3, low height in sky, visible from December to February 2025, then every two years)
• Mercury (maximum M = -2.2, low height in sky, visible every year for about 3 weeks, in spring and summer in the evening, in autumn and winter in the morning)
• The star Sirius in the constellation Canis Major (M = -1.44)
• Saturn (maximum M = -0.55 (rings included), low height in sky, visible every year in all seasons but rarely in spring)
• The star Arcturus in the constellation Boötes (M = -0.05)
• The star Vega in the constellation Lyra (M = 0.03)
• The star Capella in the constellation Auriga (M = 0.08)
• The star Rigel in the constellation Orion (M = 0.18)
• The star Procyon in the constellation Canis Minor (M = 0.40)
• The star Betelgeuse in the constellation Orion (M = 0.45)
• The hyades cluster in the constellation Taurus (M = 0.50)
• The star Altair in the constellation Aquila (M = 0.76)
• The star Aldebaran in the constellation Taurus (M = 0.87)
• The star Spica in the constellation Virgo (M = 0.98)
• The star Antares in the constellation Scorpio (M = 1.06)
• The star Pollux in the constellation Gemini (M = 1.16)
• The Melotte 20 cluster in the constellation Perseus (M = 1.20)
• The star Deneb in the constellation Cygnus (M = 1.25)
• The star Regulus in the constellation Leo (M = 1.36)
• The star Adhara in the constellation Canis Major (M = 1.50)
• The Pleiades cluster in the constellation Taurus (M = 1.60)
• The star Shaula in the constellation Scorpio (M = 1.62)
• The star Bellatrix in the constellation Orion (M = 1.64)
• The star Elnath in the constellation Taurus (M = 1.65)
• The star Alnilam in the constellation Orion (M = 1.69)
• The star Alnitak in the constellation Orion (M = 1.74)
• The star Alioth in the constellation Ursa Major (M = 1.76)
• The star Mirfak in the constellation Perseus (M = 1.79)

C4.2. List of constellations :

The International Astronomical Union (IAU) defined 88 official constellations in 1922 [IAU1]. They cover the entire celestial sphere, divided between the northern and southern hemispheres.
They are distributed as follows :
* 54 constellations visible totally or partially from Metropolitan France
    - 7 constellations visible all year round
    - 20 seasonal constellations visible during the extended summer (May to October)
    - 15 seasonal constellations visible during the extended winter (November to April)
    - 12 constellations that are difficult to see with the naked eye
* 34 constellations not visible from Metropolitan France

The 54 constellations visible totally or partially from Metropolitan France are as follows, listed in alphabetical order :

• Andromeda (Andromeda)
• The Arrow (Sagitta)
• The Berenices's Hair (Coma Berenices)
• The Bull (Taurus)
• Cassiopeia (Cassiopeia)
• Cepheus (Cepheus)
• The Charioteer (Auriga)
• The Crab (Cancer)
• The Crow (Corvus)
• The Cup (Crater)
• The Dolphin (Delphinus)
• The Dove (Columba)
• The Dragon (Draco)
• The Eagle (Aquila)
• The Fishes (Pisces)
• The Giraffe (Camelopardalis)
• The Great Bear (Ursa Major)
• The Great Dog (Canis Major)
• The Hare (Lepus)
• Hercules (Hercules)
• The Herdsman (Boötes)
• The Hunting Dogs (Canes Venatici)
• The Lion (Leo)
• The little Bear (Ursa Minor)
• The Lesser Dog (Canis Minor)
• The Little Fox (Vulpecula)
• The Little Horse (Equuleus)
• The Lesser Lion (Leo Minor)
• The Lizard (Lacerta)
• The Lynx (Lynx)
• The Lyre (Lyra)
• The Northern Crown (Corona Borealis)
• Ophiuchus (Ophiuchus)
• Orion (Orion)
• Pegasus (Pegasus)
• Perseus (Perseus)
• The Ram (Aries)
• The River (Eridanus)
• Sagittarius (Sagittarius)
• The Scales (Libra)
• The Scorpion (Scorpius)
• The Sea Goat (Capricornus)
• The Sextant (Sextans)
• The Shield (Scutum)
• The Serpent (Serpens)
• The Southern Fish (Piscis Austrinus)
• The Swan (Cygnus)
• The Triangle (Triangulum)
• The Twins (Gemini)
• The Unicorn (Monoceros)
• The Virgin (Virgo)
• The Water Bearer (Aquarius)
• The Water Snake (Hydra)
• The Whale (Cetus)

These constellations are described below, classifying them by period of year and then by position in the sky, according to the following definitions :

• The official name of the constellation is the Latin name or its abbreviation (example for The Great Bear : Ursa Major, UMa).
  
• The position is given for an observer located at the latitudes of Paris (about 49 North), in night conditions around 10 p.m. and for the periods of the year when each constellation is visible.
  
• The height ("low", "average", "high", "very high") is the actual height seen by this observer by gradually raising his head, the "low" position being close to the horizon and the "very high" position close to the zenith.
  
• The simple shape is based on the stars clearly visible to the naked eye, described as "bright" (apparent magnitude M < 4.0), some of which are "super-bright" (M < 1.6).
• The alternative shape is based on the symbolic or mythological representation of the constellation.
  
• The names of stars begin with a Greek letter (α, β, γ, δ, ε, ζ η, θ, ι, κ, λ μ, ν, ξ, ο, π, ρ, σ, τ, υ, φ, χ, ψ, ω) usually indicating their relative brightness, followed by the genitive case of the Latin name of the constellation [IAU2]. For example: α Orionis for the brightest star in Orion. Some stars sometimes also have a traditional name, often of Arabic or Latin origin, such as Betelgeuse for α Orionis. When the Greek alphabet is exhausted, numbers or Latin letters are used.
  
• The main stars are listed in ascending order of Greek letters, with their Latin name, traditional name, apparent color and apparent magnitude [IAU2].
  

C4.3. Constellations visible all year round :

The constellations visible from Metropolitan France all year round (circumpolar constellations) are as follows (see Figures below [IST][LES]) :

• Figure 1a : The Great Bear (Ursa Major, UMa)
  • Position : Visible in north all year round, medium height in sky.
  • Simple shape : Large dipper with seven bright stars.
  • Alternative shape : Body of The Great Bear (δ, α, snout ο, υ, β, γ) with long tail (δ - ε - ζ - η), front legs (υ - φ - θ - κ - ι) and hind legs (γ - χ - ψ - ω - μ - λ and γ - χ - ν - ξ).
  • Main stars : α Ursae Majoris (Dubhe, 1.81), Merak (2.34), Phecda (2.41), Megrez (3.32), Alioth (1.76), Mizar (2.23), η (Alkaid, 1.85), θ (3.17), ι (Talitha, 3.12), κ (Alkaphrah, 4.16), λ (Tania Borealis, 3.45), μ (Tania Australis, 3.06), ν (Alula Borealis, 3.49), ξ (Alula Australis, 4.41), ο (Muscida, 3.35), υ (3.80), φ (4.55), χ (Taiyangshou, 3.69), ψ (3.00), ω (4.66), 80 (Alcor, 3.99).
• Figure 1b : The Little Bear (Ursa Minor, UMi)
  • Position : Visible in north all year round, very high in sky.
  • Simple shape : Small dipper with seven stars including three bright ones (one at the handle end containing Polaris and two at the outer edge of the dipper).
  • Alternative shape : Body of The Little Bear (β, γ, η, ζ) with long tail (ζ - ε - δ - α).
  • Main stars : α Ursae Minoris (Polaris, Nord Star, 1.97), Kochab (2.07), Pherkad (3.0), Yildun (4.35), Urodelus (4.21), Alifa al Farkadain (4.28), η (Anwar al Farkadain, 4.95).
• Figure 2 : Cassiopeia (Cassiopeia, Cas)
  • Position : Visible in north all year round, high in sky.
  • Simple shape : W (or reversed M) with seven bright stars including five stars in vertices (α to ε).
  • Alternative shape : W or M = throne of Queen Cassiopeia with two armrests (β, ε) and throne vertex (γ).
  • Main stars : α Cassiopeiae (Schedar, 2.24), Caph (2.28), Navi (2.15), Ruchbah (2.66), Segin (3.35), Fulu (3.69), η (Achird, 3.46).
• Figure 3 : The Dragon (Draco, Dra)
  • Position : Visible in north all year round, medium height in sky.
  • Simple shape : Large inverted S (as seen in a mirror) with nine bright stars, that partially winds between The Great Bear and The Little Bear.
  • Alternative shape : Head (distorted square : γ, β, ν, ξ) and tail end (λ).
  • Main stars : α Draconis (Thuban, 3.67), Rastaban (2.79), Eltanin (2.24), δ (Altais, 3.07), ζ (Aldhibah, 3.17), η (Athebyne, 2.73), ι (Edasich, 3.29), λ (Giausar, 3.82), ν (Kuma, 4.88), ξ (Grumimum, 3.73).
• Figure 4 : Cepheus (Cepheus, Cep)
  • Position : Visible in north all year round, high in sky.
  • Simple shape : Polygon with seven bright stars.
  • Alternative shape : Child's house (rectangle α, β, ι, ζ) with pointed roof (γ).
  • Main stars : α Cephei (Alderamin, 2.45), Alfirk (3.23), γ Errai (3.21), δ (3.5), ζ (3.39), η (3.41), ι (3.5), μ (3.62).
• Figure 5 : The Giraffe (Camelopardalis, Cam)
  • Position : Visible in north all year round, medium height in sky.
  • Simple shape : Group of nine stars including a bright one (β).
  • Alternative shape [IMA Girafe] : Giraffe with body (α, β, γ, BE), legs (BE-CS, β-7) and long neck (α, HD 42818, HD 49878, VZ) pointing towards Polaris.
  • Main stars : α Camelopardalis (4.26), β (4.03), γ (4.59), BE or HD 23475 (4.39), CS or HD 21291 (4.21), 7 or HD 31278 (4.43), HD 42818 (4.76), HD 49878 (4.55), VZ or HD 55966 (4.92).
• Figure 6 : The Lynx (Lynx, Lyn)
  • Position : Visible in north all year round, high in sky.
  • Simple shape : Broken line with seven stars including three bright ones (α, 38, 10 UMa).
  • Alternative shape [IMA Lynx] : The brightest star is α.
  • Main stars : α Lyncis (3.14), 38 (3.82), 37 ou HD 81105 (5.3), 10 UMa (3.96), 31 (Alsciaukat, 4.25), 21 (4.61), 15 (4.35), 2 (4.44).

C4.4. Summer seasonal constellations :

The seasonal constellations visible from Metropolitan France during the extended summer (May to October) are the following (see Figures below [IST][LES]) :

• Figure 1 : The Lyre (Lyra, Lyr)
  • Position : Visible in southeast in summer, very high in sky (nearly at zenith in early evening).
  • Simple shape : Super-bright star (Vega, white) attached to a small parallelogram of four stars including two bright ones.
  • Alternative shape : Sound box with strings base (parallelogram : β, γ, δ, ζ) and point of strings attachment (α).
  • Main stars : α Lyrae (Vega, blue-white, 0.03), Sheliak (3.52), γ (Sulafat, 3.25), δ (4.3), ε (4.6), ζ (5.0).
• Figure 2 : The Eagle (Aquila, Aql)
  • Position : Visible in south in summer, medium height in sky.
  • Simple shape : Group of nine bright stars ending by Altair, super-bright and white star.
  • Alternative shape : Large figure composed of a head (γ-α-β) centered on Altair (α), a linear body (α-δ-λ), a tail (λ) and two straight wings (δ-ζ and δ-θ) turned towards the head.
  • Main stars : α Aquilae (Altair, white, 0.76), Alshain (3.71), γ (Tarazed, 2.72), δ (3.36), ε (4.02), ζ (Okab, 2.99), η (3.87), θ (3.24), ι ou 12 (4.02), λ (3.43).
• Figure 3 : The Swan (Cygnus, Cyg)
  • Position : Visible in east in summer, high in sky.
  • Simple shape : Group of nine bright stars ending by Deneb, super-bright and white star.
  • Alternative shape : Large cross composed of a tail (α, Deneb), a body (α-γ), a long neck (γ-η-β), a head (β) and two broken wings (γ-ε-ζ and γ-δ-ι) turned towards the tail.
  • Main stars : α Cygni (Deneb, white, 1.25), β (Albireo, 3.05), γ (Sadr, 2.23), Fawaris (2.90), ε (Aljanah, 2.48), ζ (3.20), η (3.89), ι (3.76), κ (3.80).
• Figure 4 : The Herdsman (Boötes, Boo)
  • Position : Visible in west in summer, high in sky.
  • Simple shape : Group of seven bright stars ending in a super-bright one (Arcturus, orange).
  • Alternative shape : Child's kite with diamond-shaped canvas (α, ε, δ, β, γ, ρ, α) and floating tail (α, η).
  • Main stars : α Boötis (Arcturus, orange, -0.05), β (Nekkar, 3.49), γ (Seginus, 3.04), δ (3.47), ε (Izar, 2.35), ζ (4.5), η (Muphrid, 2.68), θ (Asellus Primus, 4.04), ρ (3.57).
• Figure 5 : The Northern Crown (Corona Borealis, CrB)
  • Position : Visible in west in summer, high in sky.
  • Simple shape : Semicircle of seven stars including three bright ones.
  • Alternative shape : Divine crown.
  • Main stars : α Coronae Borealis (Alphecca, 2.22), β (Nusakan, 3.66), γ (4.05), δ (4.57), ε (4.14), θ (4.22), ι (4.98).
• Figure 6 : Hercules (Hercules, Her)
  • Position : Visible in south in summer, high in sky.
  • Simple shape : Group of fourteen bright stars, four of which form a square (ε, ζ, η, π).
  • Alternative shape : Hercules in inverted position, with head (α), shoulders (β, δ), arms (β - γ and δ - ο), hips (ζ, ε);, legs (ζ - η - τ and ε - π - ι).
  • Main stars : α Herculis (Rasalgethi, 3.37), β (Kornephoros, 2.78), γ (3.75), δ (Sarin, 3.12), ε (3.92), ζ (2.81), η (3.48), θ (3.86), ι (3.80), μ (3.42), ξ (3.70); ο (3.83), π (3.16), σ (4.18), τ (3.89).
• Figure 7 : The Scorpion (Scorpius, Sco)
  • Position : Visible in south in summer, very low in sky.
  • Simple shape : Large S with nineteen bright stars including a super-bright one (Antares, red).
  • Alternative shape : Scorpion body (large S) with broken tail (λ), heart (α), and pincers (β1 - δ and ρ - π).
  • Main stars : α Scorpii (Antares, red, 1.06), β1 (Acrab, 2.56), δ (Dschubba, 2.29), ε (Larawag, 2.29), ζ2 (3.62), η (3.33), θ (Sargas, 1.86), ι (3.03), κ (2.39), λ (Shaula, 1.62), μ01 (Xamidimura, 2.99), μ02 (Pipirima, 3.56), ν (4.00), π (Fang, 2.89), ρ (Iklil, 3.87), σ (Alniyat, 2.90), τ (Paikauhale, 2.82), υ (Lesath, 2.70), ω (3.93), G (Fuyue, 3.19).
• Figure 8 : The Scales (Libra, Lib)
  • Position : Visible in southeast in spring, medium height in sky.
  • Simple shape : Polygon with six bright stars, four of which form a rectangle (α2, β, γ, σ).
  • Alternative shape : Hanging scale with horizontal flail (α, β) and weighing trays (γ, σ).
  • Main stars : α2 Librae (Zubenelgenubi, 2.75), β (Zubeneschamali, 2.61), γ (Zubenelhakrabi, 3.91), σ (Brachium, 3.25), τ (3.66), υ (3.60).
• Figure 9 : Sagittarius (Sagittarius, Sgr)
  • Position : Visible in south in summer, very low in sky.
  • Simple shape : Group of fifteen bright stars.
  • Alternative shape [IMA Sagittaire] : Teapot body (trapezoid : δ, ε, ζ, θ) with handle (σ, τ), spout (γ) and lid (λ).
  • Main stars : α Sagittarii (Rukbat, 3.96), β1 (Arkab Prior, 3.96), Alnasi (2.98), Kaus Media (2.72), Kaus Australis (1.79), Ascella (2.60), η (3.11), θ1 (4.21), ι (4.16), λ (Kaus Borealis, 2.82), μ (Polis, 3.84), ξ2 (3.51), ο (4.51), π (Albaldah, 2.88), ρ1 (3.93), σ (Nunki, 2.05), τ (3.32), φ (3.17), χ1 (5.03), ω (4.51), 43 (4.88), 62 (4.45).
• Figure 10a : Ophiuchus (Ophiuchus, Oph)
  • Position : Visible in south in summer, medium height in sky.
  • Simple shape : Polygon with twelve bright stars, five of which form an irregular pentagon (α, β, η, ζ, δ).
  • Alternative shape [IMA Ophiuchus] : Man with head (α), shoulders (β, κ), hands holding The Serpent (ν, δ), hips (η, ζ), feet (45, ω).
  • Main stars : α Ophiuchi (Rasalhague, 2.08), Cebalrai (2.76), Brachium (3.49), Yed Prior (2.73), Yed Posterior (3.23), Cebalrai (2.58), η (Sabik, 2.43), θ (3.27), ι (3.85), κ (3.69), λ (Marfik, 3.82), ν (3.32), φ (4.28), χ (4.42), ψ (4.50), ω (4.45), 36 (4.33), 45 (4.28), 67 (3.93), 70 (5.00), Melotte 186 (3.0, star cluster including 67).
• Figure 10b : The Serpent (Serpens, Ser)
  • Position : Visible in south in summer, medium height in sky.
  • Simple shape : Group of bright stars in two parts (eight for The Serpent's Head forming a Y and five almost aligned for The Serpent's Tail).
  • Alternative shape : Two non-contiguous half-constellations (The Serpent's Head and The Serpent's Tail).
  • Main stars (The Serpent's Head) : α Serpentis (Unulkalhai, 2.63), β (3.65), γ (3.85), δ (3.80), ε (3.71), κ (Gudja, 4.09), μ (3.54), ω (4.26).
  • Main stars (The Serpent's Tail) : η (3.26), θ1 (Alya, 4.03), ν (4.32), ξ (3.54), ο (4.27).
• Figure 11 : Pegasus (Pegasus, Peg)
  • Position : Visible in southeast in autumn, high in sky.
  • Simple shape : Group of eleven bright stars, four of which form a large empty square (α, β, γ, δ).
  • Alternative shape : Body of the winged horse Pegasus (central square : α, β, γ, δ), head down (θ), muzzle (ε), front legs (β - η - π and β - μ - κ).
  • Main stars : α Pegasi (Markab, 2.49), Scheat (2.44), Algenib (2.83), δ (Alpheratz, blue, 2.07, bordering Andromeda), Enif (orange, 2.38), ζ (Homan, 3.41), η (Matar, 2.93), θ (Biham, 3.52), ι (3.77), κ (4.13), λ (3.96), μ (Sadalbari, 3.51), ξ (4.20), π (4.28).
• Figure 12 : Andromeda (Andromeda, And)
  • Position : Visible in east in autumn, high in sky.
  • Simple shape : Group of eight bright stars including a super-bright one (Alpheratz, blue).
  • Alternative shape : Andromeda - daughter of Cassiopeia : four star broken line (head α, shoulders δ, hips β, left foot γ), right foot (51), left hand (η), right hand (λ, ο).
  • Main stars : α Andromedae (Alpheratz, bleue, 2.07), β (Mirach, 2.07), γ (Almach, 2.10), δ (3.27), ε (4.37), ζ (4.08), η (4.40), θ (4.61), ι (4.29), κ (4.14), λ (3.82), μ (3.86), ν (4.53), ξ (4.88), ο (3.62), π (4.00), ρ (5.18), σ (4.52), τ (4.94), υ (4.10), φ (4.25), χ (5.02), ψ (4.95), ω (4.83), 51 (Nembus, 3.59).
• Figure 13 : The Fishes (Pisces, Psc)
  • Position : Visible in south in automn, medium height in sky.
  • Simple shape : Large V with three bright stars and a base α.
  • Alternative shape : Two fishes (small polygons : γ and τ) each connected by a thread to a central knot (α).
  • Main stars : α Piscium (Alrescha, 3.82), γ (3.69), η (Alpherg, 2.88), τ (4.5), ω (4.03).
• Figure 14 : The Whale (Cetus, Cet)
  • Position : Visible in south in autumn, low in sky.
  • Simple shape : Polygon with six bright stars extended by a line of three other bright ones.
  • Alternative shape : Polygonal head (ζ, τ, mouth β, ι, η, θ) with linear body (ζ, ο, δ, γ, tail α).
  • Mains stars : α Ceti (Menkar, 2.54), Diphda (2.04), Kaffaljidhma (3.56), δ (4.06), ζ (Baten Kaitos, 3.74), η (3.46), θ (3.60), ι (3.56), ο (Mira, 6.47), π (4.25), τ (3.49), υ (3.96).
• Figure 15 : The Water Bearer (Aquarius, Aqr)
  • Position : Visible in south in autumn, medium height in sky.
  • Simple shape : Group of eight bright stars, four of which form a broken line (δ, α, β, ε).
  • Alternative shape : Body of The Water Bearer Aquarius (δ, τ, λ) with head or shoulders (α, β), and urn filled with water (γ, ζ, η, π).
  • Main stars : α Aquarii (Sadalmelik, 2.95), Sadalsuud (2.90), Sadachbia (3.86), Skat (3.27), Albali (3.78), ζ (3.65), η (4.04), θ (4.16), ι (4.27), λ (Hydor, 3.73), π (4.66), τ (4.0), φ (4.22), 88 (3.68).
• Figure 16 : The Sea Goat (Capricornus, Cap)
  • Position : Visible in southeast in autumn, low in sky.
  • Simple shape : Flattened triangle with eight bright stars.
  • Alternative shape : Body of a goat (polygon : β1, δ, ω) with horns (α2) and tail (δ).
  • Main stars : α2 Capricorni (Algedi, 3.58), β1 (Dabih, 3.05), Nashira (3.69), δ (Deneb Algedi, 2.85), ζ (3.77), θ (4.08), ι (4.27), π (5.08), ψ (4.13), ω (4.12), 24 (4.49), 36 (4.50).
• Figure 17 : The Arrow (Sagitta, Sge)
  • Position : Visible in south in summer, medium height in sky.
  • Simple shape : Arrow with four stars including two bright ones.
  • Alternative shape : Arrow in flight with head (γ), shaft (γ - δ) and fletching (α, β).
  • Main stars : α Sagittae (Sham, 4.39), β (4.38), γ (3.51), δ (3.82).
• Figure 18 : The Dolphin (Delphinus, Del)
  • Position : Visible in south in summer, medium height in sky.
  • Simple shape : Small diamond with four stars including two bright ones, extended by a tail.
  • Alternative shape : Dolphin jumping out of the water with body (α, β, γ, δ) and tail (ε).
  • Main stars : α Delphini (Sualocin, 3.77), β (Rotanev, 3.64), γ (4.27), δ (4.43), ε (Aldulfin, 4.03).
• Figure 19 : The Shield (Scutum, Sct)
  • Position : Visible in south in summer, low in sky.
  • Simple shape : Small elongated diamond with four stars including a bright one.
  • Alternative shape : Diamond-shaped Roman shield.
  • Main stars : α Scuti (3.85), β (4.22), γ (4.67), δ (4.70), ε (4.88), ζ (4.66), η (4.83).

C4.5. Winter seasonal constellations :

The seasonal constellations visible from Metropolitan France during the extended winter (November to April) are the following (see Figures below [IST][LES]) :

• Figure 1 : The Great Dog (Canis Major, CMa)
  • Position : Visible in southeast in winter, low in sky.
  • Simple shape : Group of ten bright stars including two super-bright ones (Sirius, blue-white ; Adhara, blue).
  • Alternative shape : Body of The Great Dog (trapezoid : α, β, ε, δ) with tail (δ-η) and head (small triangle : γ, θ, ι).
  • Main stars : α Canis Majoris (Sirius, blue-white, -1.44), Mirzam (1.98), Muliphein (4.11), Wezen (1.83), Adhara (blue, 1.50), Furud (3.02), η (Aludra, 2.45), θ (4.07), ι (4.37), κ (3.96), λ (4.48), μ (5.00), ν2 (3.91), ν3 (4.41), ξ1 (4.33), ξ2 (4.54), ο1 (4.84), ο2 (3.04), π (4.68), σ (Unurgunite, 3.49), τ (4.40), ω (4.01), 29 (4.84).
• Figure 2 : The Lesser Dog (Canis Minor, CMi)
  • Position : Visible in southeast in winter, medium height in sky.
  • Simple shape : Group of two bright stars including a super-bright one (Procyon, white).
  • Alternative shape : Body of The Lesser Dog with head (α) and tail (β).
  • Main stars : α Canis Minoris (Procyon, white, 0.40), β (Gomeisa, 2.89), γ (4.34), ε (4.99), 14 (5.12).
• Figure 3 : Orion (Orion, Ori)
  • Position : Visible in south in winter, medium height in sky.
  • Simple shape : Group of twelve bright stars including two super-bright ones (Betelgeuse, red ; Rigel, blue) forming mainly an hourglass or a bow tie, large rectangle (α, γ, β, κ) crossed by a belt of three aligned stars (δ, ε, ζ).
  • Alternative shape : Body and legs of the hunter Orion (hourglass : α, β, γ, κ), belt of three aligned stars (δ, ε, ζ), right arm holding a bow (π01 to π06).
  • Main stars : α Orionis (Betelgeuse, red, 0.45), β (Rigel, blue, 0.18), Bellatrix (1.64), Mintaka (2.25), Alnilam (1.69), ζ (Alnitak, 1.74), η (3.35), κ (Saiph, 2.07), λ (Meissa, 3.39), μ (4.12), ο2 (4.1), π03 (Tabit, 3.19), π04 (3.7), π05 (3.7).
• Figure 4 : The Hare (Lepus, Lep)
  • Position : Visible in south in winter, low in sky.
  • Simple shape : Group of eight stars, four of which form a trapezoid (α, β, ε, μ).
  • Alternative shape : Hare body (α, β, γ, δ, μ, ζ) with nose (ε), ears base (μ) and ears (λ, κ).
  • Main stars : α Leporis (Arneb, 2.58), Nihal (2.81), γ (3.6), δ (3.9), ε (3.19), ζ (3.55), η (3.72), θ (4.67), κ (4.35), λ (4.29), μ (3.29).
• Figure 5 : The Bull (Taurus, Tau)
  • Position : Visible in south in winter, high in sky.
  • Simple shape : Large V with eleven bright stars including a super-bright one (Aldebaran, orange).
  • Alternative shape : Head of The Bull (Hyades), eye (α), tip of each horn (β on the right and ζ on the left) and body (λ, ξ, ο).
  • Main stars : α Tauri (Aldebaran, orange, 0.87, located very close to the base of V), β (Elnath, blue, 1.65), γ (Prima Hyadum, 3.65), δ (Secunda Hyadum, 3.78), ε (Ain, 3.53), ζ (Tianguan, 2.97), η (Alcyone, 2.85), θ (3.40), λ (3.47), ξ (3.73), ο (3.61), τ (4.28), C41 or Hyades (0.50, star cluster including γ, δ, ε and θ), M45 or Pleiades (1.60, star cluster including η).
• Figure 6 : The Charioteer (Auriga, Aur)
  • Position : Visible in south in winter, very high in sky.
  • Simple shape : Hexagon with six bright stars (α, β, θ, γ, ι, ε) including a super-bright one (Capella, yellow).
  • Alternative shape : Goatherd and charioteer, with feet (κ, γ), shoulders (α, β), head (δ) and kid (ε, ζ, η).
  • Main stars : α Aurigae (Capella, yellow, 0.08), Menkalinan (1.90), γ (Elnath, blue, 1.65, bordering The Bull), δ (3.72), ε (Almaaz, 3.03), ζ (Saclateni, 3.69), η (Haedus, 3.18), θ (Mahasim, 2.65), ι (Hassaleh, 2.69), ν (3.97), τ (4.50), υ (4.74), ψ1 (4.91), ψ2 (4.79), ψ4 (5.02), ψ5 (5.25), ψ6 (5.22), ψ7 (5.02), ψ8 (6.48).
• Figure 7 : Perseus (Perseus, Per)
  • Position : Visible in northwest in winter, medium height in sky.
  • Simple shape : Group of nine bright stars including a super-bright one (Mirfak, white).
  • Alternative shape : Large Y with three branches (α-β, α-γ and α-δ-ε-ζ) centered on Mirfak (α).
  • Main stars : α Persei (Mirfak, white, 1.79), β (Algol, 2.09), γ (2.93), δ (3.01), ε (2.90), ζ (2.85), η (Miram, 3.77), θ (4.12), ι (4.05), κ (Misam, 3.79), λ (4.29), μ (4.16), ν (3.77), ξ (Menkib, 3.98), ο (Atik, 3.84), ρ (3.32), υ (4.10), φ (4.06), Melotte 20 (1.20, star cluster including α and δ).
• Figure 8 : The Ram (Aries, Ari)
  • Position : Visible in southwest in winter, high in sky.
  • Simple shape : Broken line of three bright stars.
  • Alternative shape : Horned head of The Ram (α, β) ; tail (41 Ari).
  • Main stars : α Arietis (Hamal, 2.01), Sheratan (2.64), γ (Mesartim, 4.75), 41 (Bharani, 3.61).
• Figure 9 : The Triangle (Triangulum, Tri)
  
  • Position : Visible in west in winter, high in sky.
  • Simple shape : Elongated triangle of three bright stars.
  • Alternative shape : Ancient geometric figure.
  • Main stars : α Trianguli (Mothallah, 3.42), β (3.0), γ (4.0).
• Figure 10 : The Twins (Gemini, Gem)
  • Position : Visible in east in winter, medium height in sky.
  • Simple shape : Group of eleven bright stars including two super-bright ones (Pollux, orange, and Castor, white), forming a large elongated rectangle.
  • Alternative shape : two parallel bodies : twin Castor with head (α), shoulders (τ), hands (ι, θ), belly (ε) and feet (ν, η) ; twin Pollux with head (β), shoulders (υ), hands (ι, κ), belly (δ) and feet (ξ, γ).
  • Main stars : α Geminorum (Castor, white, 1.98), β (Pollux, orange, 1.16), Alhena (1.93), Wasat (3.50), Mebsuta (3.06), ζ (Mekbuda, 4.01), η (Propus, 3.31), ι (3.79), κ (3.57), λ (3.58), μ (Tejat, 2.87), ξ (Alzirr, 3.35), ρ (4.18), υ (4.04), 1 (4.15).
• Figure 11 : The Crab (Cancer, Cnc)
  • Position : Visible in southwest in spring, high in sky.
  • Simple shape : Large Y with four bright stars.
  • Alternate shape : Crab with pincers (α, β) and tail (ι)
    
  • Main stars : α Cancri (Acubens, 4.26), β (Tarf, 3.53), γ (Asellus Borealis, 4.66), δ (Asellus Australis, 3.94), η (5.33), θ (5.33), ι (4.03), M44 (3.1, star cluster).
• Figure 12 : The Lion (Leo, Leo)
  • Position : Visible in south in spring, high in sky.
  • Simple shape : Group of nine bright stars including a super-bright one (Regulus, blue).
  • Alternative shape [IMA Lion] : Body of the crouching lion (flattened trapezoid : α, β, δ, γ), head (ε), mane (ε, μ, ζ, γ).
  • Main stars : α Leonis (Regulus, blue, 1.36), Denebola (2.14), γ1 (Algieba, 2.61), Zosma (2.56), Ras Elased Australis (2.98), ζ (Adhafera, 3.43), η (3,49), θ (Chertan, 3.33), μ (Rasalas or Ras Elased Borealis, 3.88).
• Figure 13 : The Virgin (Virgo, Vir)
  • Position : Visible in southeast in spring, medium height in sky.
  • Simple shape : Group of nine bright stars including a super-bright one (Spica, blue).
  • Alternative shape : Virgin body with head (β, ν, ο), neck (η), chest (γ), belly (ζ), right arm (γ, δ, ε), left arm (γ, α), feet (μ, 109).
  • Main stars : α Virginis (Spica, blue, 0.98), Zavijava (3.59), Porrima (2.74), Minelauva (3.39), Vindemiatrix (2.85), Heze (3.38), η (Zaniah, 3.89), θ (4.38), ι (4.08), κ (4.18), λ (4.52), μ (3.88), ν (4.03), ο (4.12), τ (4.27), χ (4.66), 109 (3.73).
• Figure 14 : The Crow (Corvus, Crv)
  • Position : Visible in southeast in spring, low in sky.
  • Simple shape : Polygon with five stars including four bright ones.
  • Alternative shape : Crow in flight with eye (ε), beak tip (α), legs (β) and wings (γ, δ).
  • Main stars : α Corvi (Alchiba, 4.02), Kraz (2.65), Gienah (2.58), Algorab (2.94), ε (3.02), η (4.30).
• Figure 15 : The Cup (Crater, Crt)
  • Position : Visible in south in spring, low in sky.
  • Simple shape : Polygon with four stars including a bright one.
  • Alternative shape : Wine cup with base (α, β, γ, δ) and chalice (δ - ε - θ and γ - ζ - η).
  • Main stars : α Crateris (Alkes, 4.08), β (4.47), γ (4.06), δ (3.56), ε (4.81), ζ (4.71), η (5.17), θ (4.70).

C4.6. Other constellations :

Other constellations are the following :

12 constellations that are difficult to see with the naked eye :

* Constellations too close to the horizon :
- The Dove (Columba, Col)
- The River (Eridanus, Eri)
- The Southern Fish (Piscis Austrinus, PsA)
- The Water Snake (Hydra, Hya)

* Constellations too faint in brightness (no star with a magnitude less than 4.0) :
- The Berenices's Hair (Coma Berenices, Com)
- The Little Fox (Vulpecula, Vul)
- The Lesser Lion (Leo Minor, LMi)
- The Lizard (Lacerta, Lac)
- The Sextant (Sextans, Sex)

* Constellations drowned in star-dense regions :
- The Hunting Dogs (Canes Venatici, CVn)
- The Little Horse (Equuleus, Equ)
- The Unicorn (Monoceros, Mon)

34 constellations not visible from Metropolitan France :

- The Air Pump (Antlia, Ant)
- The Altar (Ara, Ara)
- The Bird of Paradise (Apus, Aps)
- The Centaur (Centaurus, Cen)
- The Chameleon (Chamaeleon, Cha)
- The Chisel (Caelum, Cae)
- The Clock (Horologium, Hor)
- The Compass (Pyxis, Pyx)
- The Crane (Grus, Gru)
- The Drafting Compass (Circinus, Cir)
- The Fly (Musca, Mus)
- The Flying Fish (Volans, Vol)
- The Furnace (Fornax, For)
- The Goldfish (Dorado, Dor)
- The Indian (Indus, Ind)
- The Keel (Carina, Car)
- The Male Water Snake (Hydrus, Hyi)
- The Microscope (Microscopium, Mic)
- The Octant (Octans, Oct)
- The Painter (Pictor, Pic)
- The Peacock (Pavo, Pav)
- The Phoenix (Phoenix, Phe)
- The Reticle (Reticulum, Ret)
- The Sails (Vela, Vel)
- The Sculptor (Sculptor, Scl)
- The Southern Cross (Crux, Cru)
- The Southern Crown (Corona Australis, CrA)
- The Southern Triangle (Triangulum Australe, TrA)
- The Square (Norma, Nor)
- The Stern (Puppis, Pup)
- The Table Mountain (Mensa, Men)
- The Telescope (Telescopium, Tel)
- The Toucan (Tucana, Tuc)
- The Wolf (Lupus, Lup)

C4.7. Zodiacal constellations :

The astronomical zodiac is a band in the sky that extends about 8 on either side of the ecliptic.
It includes thirteen official constellations, which are the only ones that the Sun obscures during its annual path, as seen from Earth.
The astrological zodiac takes the names and the succession of the constellations of the astronomical zodiac, but is limited to twelve signs excluding Ophiuchus, in order to symbolically divide the ecliptic into twelve equal parts.
The vernal point (spring equinox) once marked the Sun's entry into the constellation of Aries, which justified its status as the first sign of the zodiac. But today, due to the precession of the equinoxes, this point is located in the constellation of Fishes.

The constellations of zodiac are as follows, listed in the order in which the Sun passes through them :

• 1. The Ram (Latin Aries)
• 2. The Bull (Taurus)
• 3. The Twins (Gemini)
• 4. The Crab (Cancer)
• 5. The Lion (Leo)
• 6. The Virgin (Virgo)
• 7. The Scales (Libra)
• 8. The Scorpion (Scorpius)
• 8bis. Ophiuchus (Ophiuchus), which is not included in the astrological zodiac.
• 9. Sagittarius (Sagittarius)
• 10. The Sea Goat (Capricornus)
• 11. The Water Bearer (Aquarius)
• 12. The Fishes (Pisces)

Their visibility from the northern hemisphere is as follows :
* Constellations visible all year round : none.
* Summer seasonal constellations (May to October) : The Scales, The Scorpion, Ophiuchus, Sagittarius, The Sea Goat, The Water Bearer, The Fishes.
* Winter seasonal constellations (November to April) : The Ram, The Bull, The Twins, The Crab, The Lion, The Virgin.

C4.8. Tips for good observation :

To properly observe the stars, constellations, planets and satellites in the sky, it is advisable to [CHA][PER] :

• Observe during nights close to the new moon : The Moon is absent from the night sky early in the night before the new moon (up to 3 days maximum), all night during the new moon, and late in the night after the new moon (up to 10 days maximum).
• Observe at the correct time, which is not necessarily the middle of the night (the average between sunset and sunrise), but the time given by the following shift rule : The further away from the date of the new moon, the shorter the moonless time period becomes and shifts toward the beginning of the night (sunset) on the days before the new moon, and toward the end of the night (sunrise) on the days following the new moon. The reason for this shift is that, while the Earth makes a complete rotation on its axis (24 hours), the Moon continues its course around the Earth, which means that it rises and sets about 50 minutes later each day relative to the Sun, and therefore relative to the Earth's night.
  
• Observe in clear skies (without clouds) with low humidity and no moon.
• Move away from light pollution to maximize the visibility of the stars.
• Use warm and windproof clothing.
• Use a sky map or an astronomy application to help identify constellations and stars.
• Use an infrared flashlight or activate the night mode of the mobile phone to read the maps without glare or disturbance of the night vision.
• Provide additional instruments (compass, binoculars, small telescope, camera with tripod).
• Provide protective covers for the instruments to protect them from dew, wind and rain.
• Think about your comfort during observation (ground mat, blanket or deck chair).
• Get used to the darkness (for at least 20 minutes) before observing.
• Take regular breaks to rest your eyes and avoid visual fatigue.
• To see a faint object in the night sky, look slightly to the side of its position [DAR]. The rods on the periphery of the retina do not perceive colors but are much more sensitive to dim light (grayscale).
• Keep a journal of observations to be able to compare them over time.
• Explore the myths and legends related to the constellations to enrich your experience.

C4.9. Coordinates, color and magnitude of a celestial body :

The coordinates of a celestial body are generally the equatorial coordinates (α and δ) defined as follows (see Figure above) :
- Celestial sphere : Imaginary sphere of infinite radius, centered on the Earth, onto which all celestial bodies observed from Earth are projected.
- Celestial equator : Imaginary great circle drawn on the celestial sphere, corresponding to the projection of the Earth's equator onto this sphere.
- Vernal point (γ) : Point of intersection of the celestial equator and the ecliptic at the time of the vernal equinox in the northern hemisphere.
- Right ascension (α) : Hour angle measured along the celestial equator, eastward from the vernal point, between the meridian passing through this point and the meridian passing through the celestial body. It is expressed in hours, from 0 to 24 h, with the following correspondence: 1 h = 15 . Right ascension is the celestial analog of terrestrial longitude.
- Declination (δ) : Angle measuring the distance of a celestial body from the celestial equator. It is expressed in degrees, from -90 (south celestial pole) to +90 (north celestial pole). Declination is the celestial analog of terrestrial latitude.
Example for the star Vega [IAU2] : α = 18 h 36 min 56.345 s (or 279.234735 ), δ = +38 47' 01.28" (or +38.783689 ).
The angular distance (d) separating two celestial bodies in the sky, measured from Earth, is given by the following spherical trigonometry formula :
cos(d) = sin(δ1) sin(δ2) + cos(δ1) cos(δ2) cos(α1 - α2)
where α1 and α2 are the right ascensions of the two celestial bodies, δ1 and δ2 their declinations.

The apparent color of celestial bodies (seen with the naked eye) depends mainly on their surface temperature according to the following simplified classification :
    - Blue : Very hot celestial bodies ( > 10 000 K approximately), such as Spica.
    - White : Hot celestial bodies (from 6 000 to 10 000 K approximately), such as Sirius.
    - Yellow : celestial bodies of average temperature (from 5 200 to 6 000 K approximately), such as the Sun.
    - Orange : Cold celestial bodies (from 3 700 to 5 200 K approximately), such as Aldebaran.
    - Red : Very cold celestial bodies ( < 3 700 K approximately), such as Betelgeuse.
However, factors significantly influence the apparent color :
    - Brightness (whitish effect for very bright celestial bodies)
    - Earth's atmosphere (reddish effect near the horizon due to the light diffusion in the air)
    - Interstellar dust (accentuation of red by absorption of short wavelengths (blue))
    - Interstellar gas clouds (absorption and diffusion of certain wavelengths depending on their composition)
    - Sensitivity of the human eye (attenuation of blue and red in the dark)
Warning : Contrary to popular belief (red = hot, and blue = cold), the further you go from red to blue, the higher the star surface temperature.

The apparent magnitude (M) of a celestial body corresponds to its brightness state as perceived from Earth :
    M = -2.5 log₁₀[F/F₀]
    with :
    F = luminous flux received from the celestial body (in W/m²)
    F₀ = reference luminous flux corresponding to M = 0 (historically that of Vega, before the current more precise measurements).
M is a standardized measure that takes into account four factors :
    - Intrinsic luminosity of the celestial body. It corresponds to the total power of light (L in Watt) emitted at its surface, then diffused uniformly in all directions across a spherical surface of increasing radius r.
    - Distance between the celestial body and the Earth. The apparent luminosity (I in W/m²), perceived at the distance r from the celestial body, decreases in fact according to the inverse square law : I = L/(4 π r²).
    - Extinction (absorption and diffusion of light by the Earth's atmosphere, interstellar dust and gas clouds between the celestial body and the Earth)
    - Sensitivity of the human eye (which perceives the apparent luminosity according to an inverse logarithmic scale)
Warning : The lower the numerical value (M) of the apparent magnitude, the brighter the celestial body.

C4.10. Sources relative to constellations :

[CHA] ChatGPT, le moteur d'Intelligence Artificielle développé par OpenAI.
[DAR] Découvrir le ciel à l'oeil nu, Bertrand D'Armagnac et Carine Souplet, Stelvision.
[IAU1] IAU, Les constellations.
[IAU2] IAU, Comment sont nommées les étoiles ? or Current List of IAU Star Names.
[IMA] Imago Mundi, Les 88 constellations.
[IST] iStock, Constellations.
[LES] Les Astronautes, Comment reconnaître les constellations dans le ciel ?.
[PER] Perplexity, le moteur d'Intelligence Artificielle développé par Perplexity AI.
[STE] Stelvision, Carte du ciel du jour (pour France métropolitaine ou latitudes de 40 à 55 N, avec zénith au centre de la portion de ciel visible).

C8. Moon's influence

The Moon exerts a subtle but real influence on life on Earth. Through its cycles and gravitational pull, it regulates the tides, guides certain animal behaviors, and appears to affect plant growth. In humans, its effects are more difficult to demonstrate with certainty.

1. The Moon's influence on animals
2. The Moon's influence on humans
3. The Moon's influence on plants
4. The dictons

C8.1. The Moon's influence on animals :

In animals, the Moon influences their behavior primarily through the increased brightness of a full moon. This nighttime light notably alters hunting and reproductive cycles.
Predators such as cats and owls hunt more effectively thanks to the enhanced light, while prey like rodents and insects reduce their movements to minimize the risk of being detected.
In the marine environment, many species synchronize their reproduction with lunar cycles, influenced by both light intensity and tides.
Domestic animals are sometimes more restless on full moon nights, likely due to this unusual brightness.

C8.2. The Moon's influence on humans :

In humans, the Moon's influence on sleep, mood, births, and behavior is the subject of studies that are often contradictory or inconclusive.
However, the perceived effect of the Moon could stem from a psychological phenomenon : people tend to remember unusual events more readily when they coincide with a full moon, while forgetting periods without any notable events.

C8.3. The Moon's influence on plants :

The Moon's influence on plant growth has always been a subject of lively debate between scientists and biodynamic practitioners.

According to the biodynamic approach, inherited from the work of Rudolf Steiner, solar and lunar cycles, as well as other cosmic rhythms, are the expression of cosmic forces including the Moon, the Sun, and the planets. Sap rises in plants during the waxing moon, which promotes the growth of aerial parts such as leaves and flowers, a favorable period for sowing and harvesting. Conversely, sap descends towards the roots during the waning moon, a favorable period for pruning, dividing, taking cuttings, and harvesting root vegetables.
Biodynamic practitioners also believe that the Moon's position relative to the zodiacal constellations has a specific influence on plant growth. For example, when the Moon is in front of the constellation Virgo (earth element), this period is said to particularly favor root growth, while in Libra (air element), it is thought to favor flower growth.

Conversely, according to the scientific approach, the influence of the lunar phase on plant growth has never been established in a robust, clear, and reproducible manner.
While lunar gravitational forces explain Earth's large ocean tides, they are too weak to have a significant effect on individual plants.
Furthermore, the intensity of moonlight, resulting from the reflection of solar radiation, is insufficient to influence photosynthesis and other essential biological processes.
On the other hand, it is proven that biodynamic practices have beneficial effects on soil quality and biodiversity, but these effects are attributed primarily to agricultural practices and not to the direct influences of lunar or cosmic forces claimed by biodynamics.
Thus, According to modern science, even if a lunar influence exists, it is marginal compared to other agronomic factors that influence crop management.
The key conditions for success, recognized and validated by agronomic research, are primarily linked to the following fundamental factors :

1. Quality of plant propagation material (seeds, seedlings, bulbs, cuttings) :
- Material from reliable sources (healthy and vigorous, free from diseases and pests)
- Variety adapted to the local climate, soil pH, and exposure (sunny or shaded)

2. Soil type :
- Soil drainage to prevent waterlogging around roots
- Soil enrichment with humus (manure, compost) and minerals (lime, sand, clay)
- Crop rotation to prevent disease and soil depletion
- Tilling without disturbing the soil structure to maintain its biological activity

3. Protection against climatic hazards :
- Windbreaks (hedges, nets, tunnels, greenhouses)
- Frost protection (winter fleece, thick mulch, cloches)
- Drought protection (organic mulch, appropriate watering)

4. Agricultural practices :
- Respect for planting depth and Plant spacing
- Watering at the right time and without overwatering
- Regular weeding
- Mulching to retain moisture and limit weeds
- Enriching the plant with fertilizer (nitrogen, phosphate, potassium)
- Monitoring and phytosanitary treatment

5. Planting periods :
- Season suited to each variety
- Taking into account the upcoming weather conditions
- Lunar phase, whose influence, if any, remains very marginal compared to other influences

C8.4. The dictons :

Listed below are the main sayings with a known scientific explanation.

Moon and Tides :
- The Moon rules the tides,
- When the Moon smiles, the water smiles too : The tides are directly caused by the gravitational pull of the Moon (and the Sun). And when the Moon is full or new, the Earth, Moon, and Sun are aligned (spring tides).

Moon and Animals :
- A full moon makes dogs howl and roosters stay awake,
- When the Moon is full, animals are in distress,
- A bright moon makes wolves angry,
- When the Moon is round, dogs howl at its crescent,
- A red moon makes animals and plants suffer : Nocturnal animals (wolves, dogs, birds) react to the light.

Moon and Humans :
- He who sleeps during the full moon dreams of misfortune,
- Full moon keeps everyone awake,
- Children sleep poorly during the full moon,
- Bright moon makes the heart alert : Some people sleep less deeply and for shorter periods during the full moon.
- Bright moon, prosperous love : Moonlight stimulates nighttime activity and social outings.

Moon and Plants :
- Waxing moon, rising sap,
- When the moon is waxing, everything grows,
- Waning moon, growing roots,
- When the moon is waning, everything shrinks : Lunar phases whose influence, if it exists, remains very marginal compared to other influences.
- Red moon, nothing grows,
- Red moon burns young shoots,
- Red moon makes animals and seedlings suffer : The period after Easter during which clear nights lead to heat loss through radiation, making frost possible.

Moon and Weather :
See Weather - The dictons

Copyright © 2005 Régis Petit.               Last page update : May 14, 2026.