Discovered on May 3 1764
M3 is a globular cluster. A globular cluster is just a compact collection stars; basically a tiny galaxy within a galaxy. In fact, they may be smaller galaxies captured by our much larger Milky Way galaxy. M3 is one of the finest northern globular clusters. It’s super bright (as globular clusters go anyway) and easy to spot through binoculars or a small telescope. It lies almost right in the middle of an imaginary line running from the stars Arcturus to Cor Caroli. It is made up of around 500,000 stars and is about 8 billion years old – twice as old as our star, the Sun. M3 is about 34,000 light years away from Earth, meaning it would take 34,000 years to travel to if you were travelling at the speed of light.
One notable thing about M3 is that it is home to tons of variable stars, more than any other globular cluster known. Variable stars are stars that vary in brightness. There are a couple different causes for this variation including stars of differing brightness orbiting and eclipsing each other, and even stars dying of old age causing ‘cosmic death gasps.’
I look at globular clusters like M3 and just wonder what it would be like to live on a planet around one of those stars. How bright would the night sky be?! Could you imagine how breathtakingly brilliant the stars would look at night with all of those stars within such close proximity to each other? Add on top of that the variable stars winking at you from the heavens above like cosmic lighthouses… Man, that would definitely be a sight to see.