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Calendar of astronomy, August sky

Constellation Aquila

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Updated January 21, 2013

Aquila is a constellation located around the celestial equator (blue line on the enlarged image). Aquila is easily recognizable (magnitude 4) and contains stars bright enough, it was listed by Ptolemy in the second century. This small equatorial constellation located on the Milky Way below the Swan, the evening is found west of Swan. The main star is called Altair (α Aql), it is located between his two companions, Tarazed (γ Aql) and Alshain (β Aql), the constellation shows only 3 star average brightness, but aligned. In the center of the body is the Eagle (δ Aql). The star at the tip of the tail is λ Aql. Above, northeast of the eagle's head, we see the Dauphin, the small group of stars that form a fairly tight quadrilateral. North of the head, there is a constellation Sagitta. Altair Arabic meaning "Eagle in Flight" it is the 12th brightest star in the night sky. The three stars aligned of the Aquila remind the belt of Orion. Altair is a dual system (two stars orbiting around each other), as Alshain. Three stars in the Summer Triangle are 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).


In the constellation Aquila there are several star clusters and nebulae.

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 Aquila

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

Planetary Nebula NGC 6751


Planetary nebulae are simple sphere looking like planets when viewed through a small telescope. But the Hubble Space Telescope is able to show us the details of these celestial objects. Planetary nebulae have spherical shapes varied, those are fluorescent balls of gas expelled by a central star at the end of life. This Hubble image is a composite colored example of a planetary nebula, but with complex characteristics. This image of NGC 6751 was selected in April 2000 to commemorate the tenth anniversary of Hubble in orbit. The colors were chosen to represent the relative temperatures of gas (blue, orange and red, the hottest gas at the gas coldest).
Those are the winds of intense heat and radiation from the central star that create the characteristic shape nebulae. The central star dying, shines as Suns 9000. It expels its outer gaseous layers and exposes its core burning whose strong ultraviolet radiation illuminates the ejected gas. The diameter of the nebula is about 0.85 light-years, or about 600 times the size of our solar system. NGC 6751 is 6500 light-years from us in the Aquila constellation.


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 gas cloud of the planetary nebula NGC 6751 resembles a celestial eye. The dying star is at the center and its winds eject dust from outer gaseous layers of the star.
Credit: Hubble Heritage Team (STScI/ AURA), NASA

 Planetary Nebula NGC 6751
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