# How was water formed?

We know that a planet is formed from the nebula of gas and dust. Gravity pulls the particles together in a core. So we all know that the gas cloud is a cloud of hydrogen.

But how did water form? From where did oxygen come? How did it combine to make $\text{H}_2\text{O}$?

• Related: Origin of water on Earth
– Klaus Warzecha
Mar 13 '17 at 15:31
• Old dying stars are able to fuse elements up to iron in the stellar core. The "gas and dust" you refer to contains oxygen. Hydrogen is very plentiful. Mix and combine.
– Zhe
Mar 13 '17 at 15:49
• This might get you started: space.com/16943-supernova-explosion-solar-system-formation.html Elements like Oxygen, Silicon, Iron are all formed in a supernova. As I understand it, chemistry happens too, on a limited scale, within the nebula, so you have basic building blocks. Silicates like SO2, Ices/gases like H20 and CO2, but I'll let someone smarter than me give a more complete answer. Solarsystems don't form out of hydrogen easily because it's too light, it takes a certain amount of heavier elements. Mar 14 '17 at 0:24
• @userLTK You're wrong about the first part. Oxygen, Silicon, Iron, are all formed during a star's normal lifecycle, not a supernova. Any element iron or below can be formed during a star's normal lifecycle. A supernova causes the formation of any element Uranium or below (so basically all of them). Mar 14 '17 at 1:53
• @AaronFranke You're right about that, though those elements spread across the galaxy and became part of new solar system formation from the supernova explosion. My bad. Mar 14 '17 at 2:22