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Calendar of astronomy, sky January

Constellation Orion

 Automatic translationAutomatic translation Category: children
Updated January 21, 2013

Winter sky is full of bright stars, it is mainly characterized by the Orion constellation whose brightest stars form a large "rectangle" containing three stars aligned and spaced representing the hunter's belt. A little below the belt of Orion lies the Orion Nebula or M42 (small pink dot at the bottom of the image). Orion will be a valuable asset in the search for constellations of the northern hemisphere. The orientation in the winter sky is facilitated by the figure called the Hexagon Winter, whose vertices are the star Capella, Aldebaran, Rigel, Sirius, Procyon and Castor and Pollux. Less popular but equally practical guide to the Winter Triangle is formed by Procyon, Betelgeuse and Sirius. Starting from Sirius to the south along the Milky Way, we find the constellation of Sails (Vela) and Carina (Carinae). Canopus (α Carinae) is the second star in the sky after Sirius by its brightness, it was often used for air navigation during night flights. Since Rigel in Orion (the Hunter's heel on the image), we can observe the intricacies of the constellation Eridanus until the brilliant Achernar.


nota: A constellation is a group of stars that sufficiently close to the celestial vault are gave the appearance of an imaginary figure drawn in the sky.

nota: By convention, the names of the stars in a constellation are prefixed by a Greek letter followed by the first 3 letters of the constellation, for 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).

nota: a light year is exactly 9 460 895 288 762 850 meters. 

Image: The constellation Orion in the sky of the northern hemisphere is easy to identify with its 3 stars aligned. The little pink dot at the bottom of the image is the Orion Nebula. Image reworked from the Open Source software Stellarium.

 Constellation Orion

Orion Nebula


Orion Nebula, also known as M42 through a telescope has one of the most beautiful spectacles in the sky. The glowing gas of M42 surrounds hot young stars located at the edge of a large molecular cloud located about 1350 light-years from Earth. At the heart of the nebula, four blue stars forming a trapezium illuminate long-distance dispersed matter in space. The atoms absorb the starlight and re-emit in accordance with their own colors, those of the oxygen that is in the green, hydrogen and nitrogen in red. The radio observations reveal that the Orion Nebula is only a small part of the large opaque cloud of Orion. Contraction of the cloud were born Trapezium stars, along with a group of proto-stellar nebulae behind the Orion Nebula. The Orion nebula was discovered in 1610 by Nicolas-Claude Fabri de Peiresc which was apparently the first to notice his appearance unclear. Ptolemy, Tycho Brahe and Johann Bayer identified the stars in the center of the nebula, as one big star. Galileo had detected a certain number of small stars, when he observed this region with his telescope. The Orion Nebula at a distance of 1350 light-years from the Sun, offers one of the best opportunities to study how stars are born, not only because it is the largest and closest star-forming region, but also because the energy star of the nebula have blown the dust and gas surrounding, allowing us to see.


We have this nebula with an intimate view of a broad spectrum of stars being born and evolve.

nota: M is the mark of the Messier catalog, a catalog of astronomical objects look like diffuse nebulae or galaxies.

nota: NGC (New General Catalogue) is one of the most popular catalogs in the field of astronomy with the Messier catalog.

Image: The Orion Nebula, also known as M42 or NGC1976, is a nebula of red and green color in the heart of the constellation Orion in 1 350 light years from the solar system. The nebula is a large part of the center of the image, the small nebula located above is the nebula M43.

 Orion nebula M42 and M43
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