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Calendar of astronomy, July sky

Constellation Cygnus

 Automatic translationAutomatic translation Category: children
Updated January 21, 2013

Cygnus is a large and bright constellation, sometimes called the Northern Cross in opposition to the Southern Cross, because its stars are mainly arranged in a large cross. Cygnus presents on the background of the Milky Way, it contains several bright stars and characteristics many celestial objects. In the constellation of Cygnus, the main star called Deneb (α Cyg) is on the tail of Cygnus, which its wings depployed, flew south along the Milky Way. The stars of Cygnus form a large cross and Deneb, the star placed at the top of the cross, is the brightest of the constellation. According to Greek mythology, one of the legends tells that Zeus disguised himself as a swan to seduce Leda, whom he had children Gemini and Helen of Troy. Swan could also represent Orpheus transformed into a swan after his murder and placed in the heavens next to his lyre (bottom of the image opposite). The Deneb marks one corner of the Summer Triangle, visible as soon as night fallen. Three stars in the Summer Triangle, Deneb is less brilliant, the Summer Triangle is formed by Deneb (α Cyg) in the constellation of Cygnus, Vega (α Lyr) in the constellation Lyra and Altair (α Aql ) in the constellation of the Eagle (Aquila).


Thanks to its position on the Milky Way, Swan brings together several star clusters and nebulae, including the famous NGC 7000, the nebula of North America. This nebula is a little east of Deneb, really looks like the North American continent.

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.

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

 Constellation Cygnus

Image: Constellation Cygnus. Image reworked from the Open Source software Stellarium.

North America Nebula or NGC 7000


NGC 7000 or North America nebula is a huge emission nebula in various colors that spans nearly 50 light years. NGC 7000 is visible to the naked eye in the Milky Way, 3 degrees east of the bright star Deneb in the constellation Cygnus. This nebula resembles contour of the North American continent, with a particularly good replica of the Gulf of Mexico. Several other nebulae (IC 5070, IC 5068) are similar to NGC 7000. NGC 7000 is a set in which mingle and merge, veils obscure absorbent and vast clouds of stars. In the image, dust is excited by a very hot blue star named HD 199579. NGC 7000 lies about 1500 light-years away in the constellation Cygnus. To the right of the Nebula North America, is a nebula less bright that resembles a pelican called Pelican Nebula. Both nebulae are separated by a dark absorption cloud. They can be seen with binoculars from a location benefiting from skies pure and dark.


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: Nebula North America, NGC 7000 has a shape that resembles the map of the North American continent, hence its name (here in blue), bottom right, less brilliant, the nebula Pelican Nebula (IC 5070 ) that resembles a pelican.
copyright Nicolas Outters

 North America Nebula or NGC 7000
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