Vega (α Lyr / α Lyrae / Alpha Lyrae) is the brightest star in the constellation Lyra, the fifth brightest star in the sky and the second brightest star in the Northern celestial hemisphere, after Arcturus. It can often be seen near the zenith in the mid-northern latitudes during the evening in the Northern Hemisphere summer, and during these times from mid-southern latitudes it can be seen low above the northern horizon during the Southern Hemisphere winter.
It is a "nearby star" at only 24.3 light years from Earth, and together with Arcturus and Sirius, one of the brightest stars in the Sun's neighborhood. It is one of the stars in the Local Bubble.
Vega is a vertex of the Summer Triangle, which consists of Vega (in Lyra), Deneb (in Cygnus) and Altair (in Aquila). If one is to consider this asterism a right triangle, then Vega would correspond to its right angle. It is recognisable in the northern skies for there are few bright stars in its vicinity.
Its spectral class is A0V (Sirius, an A1V, is slightly less powerful) and it is firmly in the main sequence, fusing hydrogen to helium in its core. Since more powerful stars use their fusion fuel more quickly than smaller ones, Vega's lifetime is only one billion years, a tenth of our Sun's. Vega's current age is between 200 and 500 million years. Vega is twice as massive as our Sun and burns at fifty times the power.
In about AD 14,000, Vega will become the North Star, owing to the precession of the equinoxes.
Professional astronomers have used Vega for the calibration of absolute photometric brightness scales. When the magnitude scale was fixed, Vega happened to be close to zero magnitude. Therefore the visual magnitude of Vega was decided to be, by definition, zero at all wavelengths for many years (this is no longer the case, as the apparent magnitude zero point is now most commonly defined in terms of a particular numerically specified flux). It also has a relatively flat electromagnetic spectrum in the visual region (wavelength range 350-850 nanometers, most of which can be seen with the human eye), so the flux densities are roughly equal, 2000-4000 Jy. The flux density of Vega drops rapidly in the infrared, and is near 100 Jy at 5 micrometres.
The name Vega comes from the Arabic word waqi meaning "falling", via the phrase النسر الواقع an-nasr al-wāqi‘, translated "the swooping vulture". As part of the constellation Lyra it represents a jewel set in the body of the harp.
It is known as 织女星 (Zhìnǚxīng, the Star of the Weaver Girl) in Chinese, (See Qi Xi) and Vanand in Persian tradition.