The Pleiades star cluster (M45) - also known as the Seven Sisters!
This group of 800 stars was formed about 100 million years ago. It is located 410 light years away from Earth in the constellation Taurus. (Each light year is about 6 trillion miles).
The hot blue glow of the brightest stars signifies that they were formed within the last 100 million years, and that they are very luminous and will burn out quickly (like a blue flame).
Scientists believe that these beautiful stars will live more than 200 million years before they leave forever.
This photo was taken by astrophotographer Chuck Manges. Source