Autumn constellations

Autumn constellations

The autumn constellations are the particularly visible constellations in autumn when from the end of the summer.
Andromeda is an autumn constellation, smaller than its neighbor Pegasus, it is it who contains the galaxy the closest to the Earth and it is in autumn when we observe best this constellation. The autumn sky is dominated by the square of Pegasus.
It defined by stars has, ß and it of the constellation of Pegasus (Pegasus) and the star Sirrah of the constellation of Andromeda, neighbor.

If we add to this "square" stars Mirach and Alamak of Andromeda and Algol of Persee, we obtain a figure reminding the asterism In astronomy, an asterism is a remarkable figure drawn by particularly brilliant stars. enlarged by the "pan" of the Great Bear.

Images reworked from Open Source Stellarium software.

Image: 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).

Pegasus constellation

During the autumnal season, we can be guided by the big square formed by the constellation of Pegasus to turn among stars. The constellation of Pegasus is except the Milky Way and that is why its stars get loose so sharply on the dark sky.
The most brilliant star of Pegasus has for name Markab (α Peg of magnitude 2,51 to 139,62 AL) and it is situated on the right lower corner of the big heavenly square. Other stars of the constellation of Pegasus are Schedar (β Peg of magnitude 2,46 to 199,24 AL), Enif (ε Peg of magnitude 2,40 to 672,49 AL), Biham (θ Peg of magnitude 3,54 to 96,58 AL), Algenib (γ Peg of magnitude 2,85 to 333,16 AL), Matar (η Peg of magnitude 2,95 to 214,86 AL).

This constellation owes its name to Pegasus, the winged horse of the Greek mythology. it is connected with the legend of Andromeda. It was listed from Ier century later J.C.
By Ptolémée in its Almageste and cataloged by William Herschel in 1783. The big square is a major mark of the sky, which recognizes directly in its shape, and in the absence of significant star in its perimeter.

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Andromeda constellation

If we pursue an imaginary line leaving the star situated in the left superior corner of the square of Pegasus and what we go eastward, we arrive then on the constellation of Andromeda.
This constellation contains in fact brilliant 3 stud whose names are of Arabic origin. It is about Alpheratz, about Mirach and about Almach. Almach is a beautiful double star in colors contrasted by orange and by blue.
As for Mirach, it will help the observer to find a beautiful galaxy, if he pursues from this star an imaginary line towards the northwest.
This galaxy, Messier 31, is situated in more than 2 million light years of us. We can also perceive it in the bare eye on the very clear nights.

The constellation finds a way from Algol and from the big square of Pegasus.
Leaving this square, we see being outlined an immense 'wagon', three times as big as that of the Great Bear, a formed by α And, α, β, et λ Peg (the Big square of Pegasus), then in the continuation of its diagonal, from α And, β And, γ And, and finally Algol (β Persei).

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Perseus constellation

Perseus is a very brilliant constellation, placed in a very rich environment. If we draw an imaginary line leaving the star Alamak and if we pursue this line eastward, we arrive then on stars forming the constellation of Perseus.
To the naked eye, this constellation has the shape of a semicircle to which are added some straight lines. As for the star Algol, it is a binary with eclipses, that is it changes brightness according to certain period. For Algol, the period is about 3 days. The main star names as for her Mirfak. It is a great giant distant from 470 light years.
We also find in Perseus, of magnificent heap opened observable in the bare eye as well as a gaseous nebula. The position of Perseus can be tracked down by taking the adaptation which leaves the Big square of Pegasus and goes back up along the diagonal of Andromeda until Algol de Perseus and Capella of the Coachman.

Conversely, we can leave Capella, the most brilliant star of the region, and track down its neighbors Algol (β Per) and Mirfak (α Per) in the direction of the West.
We can also find a way with regard to Cassiopeia, by following the adaptation of the median bar of its "W" in the direction of the Southeast, the adaptation which falls on Mirfak (α Per).
We can finally go back up the adaptation which leaves Rigel in Orion, pass by Aldébaran of the bull, and falls on Algol (β Per) before joining Cassiopeia in the axis of the right hand of its "W".

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The triangle constellation

The constellation of the Triangle is under the constellation of Andromeda and the southeast side of Perseus.
Three little brilliant stars of this small constellation form a sort of lengthened triangle. The main star is a dwarf situated in 64 light years of us. Furthermore, the Triangle contains a completely remarkable heavenly object. It is about the big spiral nebula Messier 33. It is a galaxy named quite justly Galaxy of the Triangle that we can observe in the bare eye on the very clear nights. That is about the third biggest galaxy of our local Group, being two others the Milky Way and the Galaxy of Andromeda.

This constellation also accommodates the nebula NGC 604 (situated in M33), the biggest region of ionized hydrogen that we know, of a diameter of 1500 years light, the opened heap C 0147+270, the spiral galaxy NGC 925 as well as NGC 672 and IC about 1727, two distant galaxies 18 million years light, but separated by only 88000 years light. The quasar 3C 48, in the North of the constellation, was one of the first ones to have been discovered.

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The Aries constellation

The Aries indicates a constellation of the zodiac.
This constellation is crossed by the Sun from April 19th till May 13th. In the order of the zodiac, the constellation is situated between Fishes on the West and Taurus in the East.
The Aries also indicates a sign of the zodiac corresponding to the sector of 30 ° of the ecliptic crossed by the Sun from March 21st till April 19th. It is in this direction that it serves to the global location of the movement, still used in astrology.
The constellation is not situated on adaptations very remarkable. It finds a way from its circle of acquaintances, in the South of Perseus and Andromeda, and on the West the bull.

It finds a way by its two main stars, α and β of the Aries, which point at nothing very evident (if it is Capella at rather big distance).
Under the constellation of the Triangle, the constellation of the Aries will be easily locatable. It is a constellation formed by stars of average brilliancy.
Hamal, Sheratan and Mesarthim is the most brilliant. Hamal is a giant whereas Mesarthim is a magnificent double star.

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