?Why don't gaseous planets catch fire or explode
Even though they are gaseous planets, it is impossible for Jupiter and Saturn to catch fire or explode.
"Why don't gaseous planets catch fire or explode?" , asks Virgile Allemand on our Facebook page . This is our question of the week. Thank you all for your participation.
We usually distinguish the rocky planets (or also called "telluric"), composed essentially of rocks and metal - Mercury, Venus, the Earth, Mars -, from the gaseous ones, made up of light gases such as hydrogen or helium - Jupiter , Saturn, Uranus, Neptune. It is impossible for the latter, the gaseous planets, to explode or catch fire. Fabrice Mottez, astrophysicist at the Universe and Theories Laboratory of the Paris-Meudon Observatory (CNRS), explains to Sciences et Avenir why.
Planets rich in hydrogen, but too poor in oxygen
"To produce fire or an explosion, you need three things: a fuel, an oxidizer, and something to start the fire, such as a spark or a source of intense heat, specifies the astrophysicist. The fuel is the gas The oxidizer is another gas that allows combustion, therefore fire, and it is generally oxygen, but it can also be ozone.
On Jupiter and Saturn, the atmosphere contains a lot of hydrogen which is a good fuel. "But there is no oxygen (or in minute traces, so not enough to start a fire) or any other oxidizer. This is why the atmosphere of these planets does not catch fire. Ditto for Uranus and Neptune: there are gases there that could be combustible (hydrogen and methane, editor's note) , but no oxidizer" , adds the specialist.
On Jupiter and Saturn there are thunderstorms, almost similar to those that detonate on Earth, with lightning (thus large sparks) and lightning . On the gas giant, some flashes even emit up to three times more energy than those on Earth. "It is fortunate that the atmospheres of these planets are deprived of oxidizer, otherwise, by catching fire, they would quickly change state!" , exclaims Fabrice Mottez.
Stars that can explode
If the question of an explosion does not arise for a planet, it arises on the other hand for certain stars, becoming supernovae . "In this case, the explosion is not of chemical origin (including a fuel, an oxidizer and a heat source, editor's note), but of thermonuclear origin... like an atomic bomb , explains the astrophysicist. The material ejected by the explosion spreads quite quickly in the Universe and is quickly "diluted". So if you are far enough from an exploding star, the explosion will not reach you, or if it does reach you, it will have no noticeable effect on your environment because the gas from the
For the explosion of a "normal" mass supernova (i.e. about 10 times the mass of the Sun), the dangerous distance is limited to 25 or 30 light-years (or about 250 trillion of kilometers). "It's not very far. We have a good knowledge of the stars at this distance from the solar system, and none of them are at risk of exploding, according to our observations", concludes Fabrice Mottez .
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