Altair

Altair (α Aql, α Aquilae) is the brightest star in the constellation Aquila and one of the closest naked-eye stars to Earth, located approximately 16.7 light-years away. It is an A-type main-sequence star, meaning it is hotter and more massive than our Sun.

Characteristics:

Altair is a relatively young star, estimated to be only a few hundred million years old. It rotates extremely rapidly, completing a full rotation in about 9 hours. This rapid rotation causes it to be oblate, meaning it is flattened at the poles and bulging at the equator. This shape affects its surface temperature, with the poles being significantly hotter than the equator.

Altair is also a Delta Scuti variable, a type of pulsating star that exhibits small variations in brightness due to radial and non-radial pulsations on its surface. These pulsations are caused by internal pressure waves within the star.

Visibility:

Altair is easily visible to the naked eye in the Northern Hemisphere during the summer months. It forms one of the vertices of the Summer Triangle, along with Vega in Lyra and Deneb in Cygnus. Its bright, white color makes it a prominent feature in the night sky.

Cultural Significance:

Throughout history, Altair has held cultural significance in various civilizations. In Chinese astronomy, it is associated with the Qixi Festival, a romantic holiday celebrating the annual meeting of the Weaver Girl (Vega) and the Cowherd (Altair). These two stars are separated by the Milky Way for most of the year and are only allowed to meet on the seventh day of the seventh lunar month. In other cultures, Altair has been used for navigation and timekeeping.