M31 The Andromeda Galaxy

This galaxy marked the beginning of our understanding of the universe's immensity.

Merely 100 years ago, Andromeda was thought to be a nebula, and many astronomers at the time believed that our Milky Way was the only galaxy in the universe. Not long after, Edwin Hubble made his famous observation, confirming Andromeda as a galaxy, and our galaxy was just one of many. From that moment, our universe expanded, and we never looked back.

The background may look a bit messy, but it was intentionally so. Every dot in the image is a star, and there are well over 10,000 stars in the background. The galaxy itself contains about a trillion stars, many of which have their own planets. Maybe, just maybe, some of them could even harbour life.

Another fun fact about Andromeda is that it's on a head-on collision course with our Milky Way. They will collide about 4.5 billion years from now, performing a spectacular cosmic dance and merging into a new elliptical galaxy. Would humans still be around to witness the show?

(The data behind this image was from Telescopelive, which I processed using Pixinsight and Photoshop)