The constellations

spring constellations

autumn constellations

not visible constellations

summer constellations

winter constellations

constellations of the zodiac

A constellation is a group of stars of the vault heavenly which enough close relations looked the appearance imagination of a figure onto the sky. A constellation is thus a asterism astronomy, an asterism is a remarkable figure drawn by particularly brilliant stars.  particular. In the sky the stars of a constellation are very remote some of the others but seem grouped together there figures. The western constellations are grouped together in two left, dividing the sky by following more or less both hemispheres of the earth, southern sky for the South and the boreal sky for the North.

By agreement the names of the stars of a constellation are prefixed by a Greek letter followed by the first 3 letters of the constellation, the example : α  Ori, β Ori, ... (Greek letters : α β γ δ ε ζ η θ ι κ λ μ ν ξ ο π ρ ς σ τ υ φ χ ψ ω).

The man is fascinated by this cosmic decoration which represents the sky observed except any artificial lighting. Stars seem quite hung on on the same distance of the earth.
The sky changes day and night all year round. At first sight the sky is strewed with thousand brilliant and twinkling stars. In theory we could see at one go of eye 3800 stars, really 2600 only are visible because of the lights parasites. It is the Earth which creates the horizon cutting in two the heavenly sphere.
In the pole all the stars turn around the top, at the same time as the horizon.
In the equator all stars get up and go to bed, the heavenly poles are on the horizon. From then on all the stars from a pole to the other one are visible at the certain moments of the year.

In average latitudes, certain stars are circumpolar A heavenly object (typically a star) is said circumpolar with regard to a given place of observation if it is visible in quite the periods of the year. In the north hemisphere, a star disappears under the horizon when the sum of its declension and the latitude of the place of observation is lower than 90 °. The 'circumpolar' notion is thus connected instead of observation. So, in the North Pole, all the stars of positive declension are circumpolar, while there is no circumpolar star in the equator. A constellation is said circumpolar if the totality of its main stars are circumpolar.  or always above the horizon while the others get up and go to bed.
Stars differ by their color, their brilliancy and their luminosity. The most brilliant stars are of magnitude 1. An observer can see stars hundred times weaker, that is of magnitude 6. Every star has a characteristic color according to its temperature:
Red (Temperature 2000° Celsius) as Ras Algethi, Proxima Centauri, Bételgeuse, Antares.
Orange as Alpha Centauri, Aldebaran, Arcturus.
Yellow (Temperature between 4000 and 6000° Celsius) as the Sun, Vindemiatrix.
White as Procyon, Sirius
Blue (Temperature between 40 000 and 100 000° Celsius) as Vega, Rigel.

It is at first the most brilliant stars which draw the attention of the observer. The Greek mythology left us in the sky of the images formed by imaginary lines that we call constellations.
These constellations have names according to their forms. These groupings of stars have no link with their distances with regard to the Earth. There are southern, equatorial or boreal constellations. Those who are observable of the north hemisphere are the equatorial and boreal constellations.
It is easy to recognize the said constellations circumpolar: it are the ones that we can observe in any seasons. These constellations are constituted by the Great Bear, by the Small She-bear, by the Dragon, by the Giraffe, by Cassiopeia, by the Lynx and by Cephee.

The Great Bear constellation (Ursa Major)

The Small She-bear is formed by 7 stars and the constellation has a shape looking like that of the Great Bear but in smaller.
The Small She-bear is a weakly brilliant constellation, which owes its celebrity to its most brilliant stud, the polar huge Star or Polaris (α UMi of magnitude 1,99 to 431,43 Al).
Other considerable stars of the constellation are Kocab (β UMi of magnitude 2,09 to 126,47 AL), Pherkad (γ UMi of magnitude 3,02 to 480,35 AL). This constellation gave several words.

  see

  see
 

Opposite to the constellation of the Great Bear, the other side of the star Polaris, we see a big "W" easily recognizable which bounds in the Milky Way, 5 stars of the constellation of Cassiopeia.
The main star of the constellation of Cassiopeia is called Shedir (α Cas of magnitude 2,26 situated to 228,56 AL).
Other stars of constellations are Caph (β Cas of magnitude 2,30 to 54,46 AL), γ Cas of magnitude 2,17 to 613,08 AL), Rucnbach (δ Cas of magnitude 2,68 to 99,41 AL), ε Cas of magnitude 3,84 to 334,18 AL. Cassiopeia is one of 88 constellations of the sky, visible in the north hemisphere.
Contrary to the Great Bear with regard to the Small She-bear.

The central point of W clocks towards the Pole star. Originally considered by Ptolémée during the editorial staff of its Almageste, the constellation represents, in the Greek mythology, queen Cassiopeia chained to its throne, woman of Céphée and mother of Andromeda.

  see

Between the constellation of Cassiopeia and the Dragon is Cepheus.
This constellation is not very visible but it reminds child's drawing representing a small house with a roof. The main star of the constellation of Cepheus is called Alderamin (α Cep of magnitude 2,47 situated to 48,80 AL). Other stars of constellations are Alfirk (β Cep of magnitude 3,25 to 595,18 AL), Roamed (γ Cep of magnitude 3,23 to 44,99 AL).

Cepheus is a weak constellation, his wife Cassiopeia is much more brilliant. In good conditions of visibility we can find the general shape, the sort of rectangle marking the bust of Cepheus with a petit point glittering in the middle, surmounted by a sort of sharp hat directed to the pole star (α UMi).

  see