Astronomy Fun Fact #25
I mentioned a "planetary nebula" in a previous fun fact, but I didn't tell you what it is.
A planetary nebula is a big cloud of glowing, ionized gas that forms after a giant star stops fusing elements in its core. It's called that because old astronomers thought they were the environments where planets form, but they were wrong! Instead, planetary nebulae are the environments where stars (and likely their planets) die.
I love this fact because it's just one example of how scientists are always learning and correcting themselves until they get to the truth.