RCW 120 is an HII emission nebula in the constellation Scorpio. At a distance of about 4,300 light-years it is also known as Sh 2-3, Gum 58, and the Green Ring Nebula.
There is an embryonic star located in the dense white area at the bottom edge of the ring. This proto-star, currently at 10 solar masses, will continue to grow by accreting more of the surrounding gas and dust. When the star ignites, likely in the next few hundred thousand years, it will become one of the brightest stars in the Galaxy.
This painting is based on an image taken by the Hershel space telescope early in its lifetime.