Jupiter and the other giant planets are made mostly of hydrogen. Hydrogen is very explosive. We have also seen lightning on some of the giant planets. Why doesn't the lightning make the hydrogen explode?
When hydrogen explodes, it does so by combining with oxygen in the following reaction:
2 H2 + O2 => 2 H2O + energy
If there is no oxygen, then the explosion cannot take place. While the gas giants are made mostly of hydrogen, they have very little oxygen in their atmospheres.
In fact, the Earth is the only planet with an oxygen-rich atmosphere. The reason is that on Earth, plants and bacteria that perform photosynthesis release oxygen. There is no known photosynthetic life on any other planet, so they have only trace amounts of oxygen in their atmospheres.
This page was last updated June 28, 2015.