Hoag’s Object — Hoag’s object is a galaxy of the type known as a ring galaxy.
A nearly perfect ring of young hot blue stars circle the older yellow nucleus of this ring galaxy 600 million light-years away in the constellation Serpens.
The galaxy is about 120,000 light-years wide, which is slightly larger than the Milky Way Galaxy. The gap separating the two stellar populations may contain some star clusters that are almost too faint to see.
As rare as this type of galaxy is, oddly another ring galaxy can be seen, between the nucleus and the outer ring at the 1:00 position.
Discovered in 1950 by astronomer Art Hoag, many of the details of the galaxy remain a mystery, foremost of which is how it formed.
Some astronomers think it was through a collision with another galaxy about 2 or 3 billion years ago but there is no sign of the second galaxy, which means the blue ring of stars may be the shredded remnants of a closely passing galaxy that were captured by the gravitational forces of the nucleic core.
Astronomical position (J2000): RA 15h17m17s DEC +2134’45″