Stars and Galaxies — Passage and Quiz

When we look up at the night sky, we see countless twinkling lights. These are stars, and they're a lot like our Sun. Stars are huge balls of gas that produce their own light and heat. They come in different colors, from red to blue, depending on how hot they are. The hottest stars are blue, while cooler stars are red.

Stars don't live forever. They're born in huge clouds of gas and dust called nebulas. Over millions of years, they grow and change. Some stars, like our Sun, will eventually swell up into red giants before shrinking down to white dwarfs. The biggest stars have more dramatic endings - they explode in huge bursts called supernovas!

But stars aren't just floating alone in space. They're grouped together in huge collections called galaxies. Our galaxy is called the Milky Way, and it's home to hundreds of billions of stars! If you've ever seen a faint, milky band across the night sky, you've seen part of our galaxy.

The Milky Way is shaped like a giant spiral, with long arms curling around a central bulge. Our Sun is in one of these spiral arms, about halfway from the center to the edge of the galaxy. It takes about 225 million years for our Sun to make one trip around the galaxy!

But the Milky Way isn't the only galaxy out there. There are billions of galaxies in the universe, each with billions of stars. Some galaxies are spiral-shaped like ours, while others are elliptical (oval-shaped) or irregular. The closest big galaxy to us is called Andromeda, and it's so far away that its light takes 2.5 million years to reach us!

Astronomers study stars and galaxies to learn about the history and future of the universe. They use powerful telescopes on Earth and in space to see farther and farther into the cosmos. Every new discovery helps us understand a little more about our amazing universe and our place in it.

The next time you look up at the night sky, remember that you're seeing just a tiny part of our vast and wonderful universe!