The Galactic System

Stars

With so many stars in our solar system, the night sky is a beautiful sight. But not all stars are the same. In this lesson, we will explore the different types of stars so you know exactly what you're gazing at each night.

What is a Star?

When you look up at the night sky, you see countless stars. Stars are burning balls of gas, and from a far distance, they all look pretty much the same. But did you know that there are different types of stars? Today, we will take a closer look at those stars you see way up high.

Types of Stars

Stars are often categorized by how hot they are or what gases they contain, which often ties into how big and bright they are. Let's take a look at some of the most common types of stars.

Main Sequence Stars

Let's start with the most famous type of star: the sun. The sun is a main sequence star, which is a star that continues to burn because of nuclear fusion. This means the star continuously turns the element hydrogen into the gas helium. The hotter these stars get, the brighter they shine, and they are very stable, which means they can keep burning for a very long time. Main sequence stars often last for billions upon billions of years.

Red Giant Stars

You know what happens when main sequence stars give off energy for billions of years? They eventually become made mostly of helium. These stars get bigger and bigger (about 20 times larger than the sun), and when they start to cool off, they become red giants. One well-known red giant is Betelguese. Funny name, right? You may be able to see this star with a telescope because, even though it's very far away, it's about 8,000 times brighter than the sun.

White Dwarf Stars

Another type of star is the white dwarf star. This star forms from a red giant that loses its outer layers, leaving behind mostly carbon and oxygen, then shrinks into a very compact star. It's fairly cool, and so it gives off a weak, bluish-white color.