what is altair
View full size image. Altair is a bright star in the northern summer sky that is one of the three stars that form an astronomical asterism called the Summer Triangle. The star, which is in the constellation Aquila (the Eagle), is just 16.7 light-years from Earth, making it one of the closest naked-eye stars visible in the sky. It is the 12th brightest star in the night sky with an apparent magnitude of 0.77.