Have you ever wondered where stars are born? Or where they go when they burn out? Well, the answer to both is sometimes the same! Stars start, and sometimes end, their lives in what astronomers call nebulae. Nebulae are like the nurseries of the Universe.
Image Credit: NASA Goddard
What is a Nebula?
What do you remember from your nursery? It probably looked pretty different from a nebula! A nebula is a big cloud of dust and gas. They’re found in interstellar space, or the space between stars. They look quite fuzzy in appearance, like fluffy clouds or cotton wool in the sky.
Of course, it is difficult to see them without a telescope. From Earth, there are few nebulae we can see in the night sky. One of the ones we can see is the Orion Nebula! If you want to find it, look in the sword of the constellation Orion. It’s so far away that it looks like a slightly fuzzy star.
You can see the Orion Nebula from Earth, but it’s much easier to see with a telescope! (Image Credit: NASA/JPL-Caltech)
What is a Nebula Made of?
A nebula is mostly made of hydrogen and helium gases and plasma. Some nebulae contain other gases like nitrogen, oxygen, and carbon. The material that makes up a nebula is very spread out. Even more so than oxygen is here on Earth!
This nebula, called NGC 6153, contains a lot of nitrogen! (Image Credit: NASA Goddard)
Because the material is so spread out, nebulae can be light years across. That means even if you’re traveling as fast as light does, it’d take you years to travel all the way through a nebula. That’s trillions of miles!
How do Nebulae Form?
There are a few different types of nebulae, and each forms a different way! Some nebulae form when gravity starts to pull material in the space between stars closer together. Over a very long time, the material gets pulled close enough together that it forms a nebula. Since we know that the gas in a nebula are already spread out, it is really spread out before it becomes a nebula!
Nebulae can also form after a supernova. An exploding star releases lots of gas and dust, which spreads out to form a nebula. One nebula that formed from a supernova is the crab nebula.
Nebula IC 418 surrounds a white dwarf star that was once a red giant star! (Image credit: NASA Goddard)
How do Stars Form in a Nebula?
While the gas and dust in a nebula is still spread out, gravity is still working to pull it closer together. The closer together the material gets, the stronger gravity pulls. When the material gets pulled close enough together, it forms a star! Often, stars form in small areas of a nebula where the material groups more closely together.
The video below shows the Lagoon Nebula. The bright star that you can see in the middle of the video is Herschel 36. It formed from the gas of the nebula!