You might have heard about supernovae as the largest explosions in the galaxy, or seen beautiful pictures of nebulae, but what really are they?
What is a nebula?
In one sentence, a nebula is the remnants of an old star that provides a birthplace for new stars. A supernova is a gigantic explosion that happens when the largest stars in the universe explode.
How are nebulae formed?
Stars are constantly in the middle of a tug of war, with the internal forces of the star trying to make it expand, and gravity trying to make it collapse. Usually, these forces are balanced. But when a star reaches the end of its life, the internal forces diminish, and gravity wins. This leads to the star eventually collapsing in on itself. This collapse results in a stupendous explosion, in which the star blows off its outer layers. In the nebula picture below, you can see the star in the center and the beautiful gas rings outside.
Why are nebulae so important?
These nebulae are so important to the universe because they provide a birthplace for new stars. Without them, the universe would soon be a cold, dead place. Our sun and Earth were likely formed from a nebula! Some of the dust and gas in that nebula started to clump together. As time passed, that clump grew bigger. Soon, that clump had grown big enough to become a star. The rest of the gas and dust swirled around the sun, eventually clumping together to create the planets!
How does this relate to supernovae?
Supernovae are formed the same way that nebulae are, just with much, much bigger stars. These gigantic explosions can briefly outshine entire galaxies, with billions of stars! Because of the way these huge stars work, they smash lighter elements, such as hydrogen, into life-supporting elements, such as iron. The explosions then fling these elements across the universe. Without these elements, life on Earth would not exist!
Images
The Hubble space telescope has many beautiful pictures of nebulae and supernovae. Check out some of the best down below!
The westerlund 2 nebula 
The pillars of creation 
The orion nebula 
The butterfly nebula 
The giant nebula NGC 2014 and its neighbour NGC 2020 
The bubble nebula
If you want to see more, check out the official Hubble website here: https://www.spacetelescope.org/images/archive/category/nebulae/.
Do you have any cool facts about supernovae or nebulae? Share them in the comments below!
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