It is Lord Vishnu‘s footprint in the sky.
The foot print of Lord Vishnu is found in Gaya and some other places as well.
The footprint of Vishnu is a streaming scattered group of Stars int he Milky-way Galaxy.
Here it is.
Altair. In the great astrological tradition of India, Altair represents the footprints of Vishnu, preserver and protector of the Universe.
Altair (Alpha Aquilae, Alpha Aql, α Aquilae, α Aql, Atair) is the brightest star in the constellation Aquila and the twelfth brightest starin the night sky. It is currently in the G-cloud. Altair is an A-type main sequence star with an apparent visual magnitude of 0.77 and is one of the vertices of the Summer Triangle (the other two vertices are marked by Deneb and Vega).
Altair rotates rapidly, with a velocity at the equator of approximately 286 km/s.[nb 3] A study with the Palomar Testbed Interferometer revealed that Altair is not spherical, but is flattened at the poles due to its high rate of rotation. Otherinterferometric studies with multiple telescopes, operating in the infrared, have imaged and confirmed this phenomenon.(wiki)
In classical mythology Aquila, and by extension Altair as well, was an eagle favored by Zeus. He played a part in numerous myths, including the abduction of Ganymede in which a young boy (Ganymede) is carried off to Mount Olympus on Zeus’ command to become the cupbearer to the gods. In another myth Aquila is the eagle that torments Prometheus, and is shot with a poisoned arrow by Hercules.
In India, Altair with its two flanking stars, Beta and Gamma (Tarazed and Alshain), are sometimes thought to be the celestial footprints of the god Vishnu.
Altair is separated from the similar-looking (but brighter) star Vega in the constellation Lyra by the great starlit band of the Milky Way. In Asia, this hazy band across our sky is known as the Celestial River. One story common in China, Japan and Korea a young herdsman (Altair) who falls in love with a celestial princess (Vega), who weaves the fabric of heaven. The princess became so enamored of the herdsman that she neglects her weaving duties. This acts enrages the princess’s father, the Celestial Emperor, who decrees that the herdsman must stay away from his daughter, on the opposite side of the River. The Emperor finally listened to the princess’s pleas, however, and allowed the herdsman to cross the Celestial River once per year, on the seventh day of the seventh month.
Altair is only 16.8 light-years away from Earth, making it one of our nearer stellar neighbors. At least two features of the star Altair make it distinctive.
First, Altair rotates rapidly. This star requires only about 10 hours to spin once on its axis, in contrast to 24 hours for our Earth to spin or roughly a month for our sun. In other words, this mighty star spins on its axis more rapidly than Earth! This rapid rotation tends to flatten the star a bit, much as a pizza crust flattens as it spins. Estimates are roughly that Altair’s flattening is about 14 percent. The sun also is an oblate spheroid, although its flattening is difficult to measure due to the low rotation rate.