Saturn, Methane, and Explosions
Name: David P.
One of Saturn's moons has liquid methane lakes and methane
gas clouds. Can this gas be ignited causing a giant explosion? Such
as from a lightning strike or a meteorite?
I do not know if you remember the Jupiter - Shoemaker Levy 9
collisions back in 1994.
Note that Jupiter is a gas planet composed mostly of the flammable
H2 gas (liquid and solid probably in the inner core). The video
shows massive explosions and black marks on the planet for months -
but the entire planet did not burn. Why?
From the perspective of chemistry, combustion (or ignition) is
nothing more than a chemical reaction (that produces a lot of heat)
wherein the "fuel" (in this case, methane) combines chemically with
an oxidant (usually, but not necessarily, oxygen), under conditions
where some initial energy (think of the necessity of striking a
match before it can burn) is supplied.
So, we need: fuel, oxidant, ignition energy or conditions.
We know we have the fuel (methane). I'm not sure what the ignition
energy requirements are for methane at the temperatures and
pressures of Saturn's moons, but we could assume that a meteor
strike would supply enough such energy and if there is a spark,
could cause ignition - much like it did on Jupiter.
However, I am not sure that there are oxidants on Saturn's moons, or
on Jupiter. From what I remember, the moons and many of the outer
planets have "reducing atmospheres" - which means that there is a
lack of oxygen or some such oxidant - which allows highly energetic
compounds like methane and ethane to exist in the first place. If
oxygen were present, we would more likely find CO2 because, even
though no ignition takes place, small oxidation reactions can and
oxidize (as oppose to reduce) the methane to CO2.
So, yes, a meteor can cause ignition, but, no, the entire planet
(Jupiter) or moon (Saturn) will not explode because there is not
enough oxidant present to keep the fires burning. The explosion we
saw in Jupiter was essentially due to the high energy plus whatever
oxidant was present from the comet/meteors, and the little in the
surrounding regions of the impact.
Greg (Roberto Gregorius)
No, I doubt it, Titan is the moon in question, but the liquid
methane is far too cold.
David H, Levy
Highly unlikely. The combustion (detonation) of gases such as methane
requires the presence of oxygen to burn (or explode). A fire requires three
components: 1. A fuel, 2. An oxidant, 3. An ignition source. Remove one of
the three, and no fire occurs.
I saw the same program and wondered about the same thing, but such a giant
explosion would require a lot of oxygen.
Here is the chemical reaction formula for burning methane:
CH4 + 2O2 => 2H2O + CO2
So you have to have 2 molecules of diatomic oxygen to each molecule of
They did not say anything about how much oxygen there was on that moon and it
is still there.
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Update: June 2012