1. An emission nebula can collapse in on itself after millions of years and form a star

2. the brightest nebula in our sky is the orion nebula, it is an emmision nebula

3. some nebula have parts of or other nebula inside of them, such as the gum nebula, which contains the much smaller vela nebula inside of it.

4. the first planetary nebula ever to be discovered was the dumbell nebula, it was discovered by charles messier.

5.  the pillars of creation are a very famous picture that nasa took of the eagle nebula, they are large pillars that form many new stars.

6. the coldest natural place in the known universe is the boomerang nebula, which hangs at only 1 degree above absolute zero.

7. planetary nebulae are composed of Mainly carbon, oxygen, nitrogen, neon, and similar weight elements. Plus small amounts of helium and metals

8. planetary nebula are sometimes called the universes recyclers.

9. sometimes, people refer to a galxie as a nebula.

10.  back in the 20th century a spiral galaxie was known as a spiral nebula, as it was not known that there were nebula in galaxies other than our own.