Before I left Academia for good, I was was a professional astronomer. I was studying the Universe by looking through the largest telescopes in the world. My main research interest was the study of extragalactic globular clusters around galaxies. Some of the questions I try to answer were: How did galaxies form? What is the role of globular clusters in galaxy formation? What is the dark matter content in galaxies?
What is a galaxy?
The bright object on the right is a galaxy. A galaxy is a collection of stars, gas, dust, planets, asteroids, comets, black holes and every other astronomical objects you can think of. Galaxies come in all shapes and sizes: galaxies can be giant, dwarf, round or flattened. Galaxies can have spiral arms, bars, shells, streams and rings. Galaxies can also be dead or alive.
If you look carefully, the picture on the right contains many different types of galaxies. By studying all the properties which characterize galaxies, astronomers can reconstruct their formation histories. Galaxies make up most of the visible light in the Universe. The reason why the night sky is full of stars and not full of galaxies, is because galaxies, unlike the stars of the Milky Way, are far far away, which means that you need a telescope to actually see them.
What is a globular cluster?
The object on the left is a globular cluster. It is about 30 light years across (that is 280000000000000000 meters) and it contains thousands of stars all compacted together. Galaxies can be surrounded by tens of thousands of globular clusters. If you look carefully at the picture of the galaxy above, you will see a multitude of small dots around it. Those are globular clusters. They appear like tiny dots because they are far way, whereas the globular cluster in this picture is relatively close to us.
Globular clusters are widely used in astrophysics. For instance they allow astronomers to study the evolution of stars, to determine the formation history of galaxies or to determine the dark matter content of galaxies. And what is dark matter anyway? Check out this excellent TED talk by Michelle Thaller to find out.
Why it is important to study the Universe?
Because it is interesting and fascinating. Science drives human progress. You could not read these words without decades of research in mathematics, chemistry, physics, astrophysics, engineering. Moreover, trying to make sense at things is what civilizations have been doing for millennia. It makes us humans. The more we understand things, the more we can find ways to improve what’s around us and make everybody’s lives a lot happier. Check out this article by Marissa Rosenberg to find out why astronomy is important for society.