1.) It is essential to use many different types of equipment because you want to know what you are seeing and with this equipment you can you also want to make the right obversions like how bright or big a star is.
2.) The missing element would be oxygen. Since earth has carbon and oxygen it makes carbon dioxide so if a different planted has oxygen it will make it so people could breath on it.
hope i helped
Collagen supported cells :)
Water is not a organic molecule
If it has valves then it is a vein.
