The most important image ever taken..
Every single speck of light you see is a galaxy, not a star.
This picture was taken looking at a completely blank spot of the sky, about the size of the tip of your pinky finger, if looking up at night.
Our own Milky Way is a spiral galaxy. These are much more massive than the relatively tiny dwarf galaxies, and contain hundreds of billions of stars. For example, the Milky Way contains 200 billion stars – 200,000,000,000 stars. The nearby Andromeda galaxy is much more massive than the Milky Way and contains 1 trillion stars; 5 times as many stars as the Milky Way.
The largest galaxies in the Universe are known as ellipticals. These enormous galaxies have lost their spiral shape through many interactions between large galaxies. They’re found at the cores of the largest galaxy clusters. The biggest galaxy ever discovered is inside the Abell 2029 cluster and contains 100 trillion stars. That’s 100,000,000,000,000 stars.
And just think, there are 100 billion galaxies in the observable Universe. When you put those numbers together, you get an estimate of 1024 stars in the entire Universe. Or a 1 followed by 24 zeroes. That’s 1,000,000,000,000,000,000,000,000 stars.
I’ve always loved this picture so much. I think the first time I saw it I didn’t understand the scale of things - I thought a nebula was generally the size of a galaxy (before I took even a remote interest in astronomy), and I didn’t understand how far away things are (I thought you came very close to the moon when you went in an airplane). But this image remains in my top five of most awe-inspiring photographs in astronomy.