A question which has haunted me for years. What temperature do small meteorites (which don't evaporate on impact) have if you find them immediately after they hit the surface. I understand that the outer parts are heated by atmospheric friction, but what about the inside? Can the inside keep its low temperature that it inherits from space?

There are some stories on the internet about meteorites that were so cold, that the moisture of the air froze on the surface of the meteorite. Can this really happen?


  • Are there numerical simulations that can prove this?

Some of the rumours are summed up here: "Frosty" meteorite (Wikipedia).

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    $\begingroup$ Since it's the surface of the meterorite that the myth talks about, and it's the friction on the surface that causes the heat, that seems a bit farcical, doesn't it? Unless it was a really slow meteorite... The Skeptics.SE site usually requires an example of the claim in question for myth-busting/proving exercises like these. I would think that that might be a good practice to follow for this site as well. Do you have a link to an example? $\endgroup$ – naught101 Apr 16 '14 at 12:19
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    $\begingroup$ @naught101 Somewhat of an explanation would be: If only the surface is heated (a few Millimeters depth with lets say 500 Kelvin) and the meteorite has a diameter of 0.5 Meter at lets say 100 Kelvin. Then the heat of the surface would be relatively small compared to the volume. The surface heat could dissipate into the air and the inside of the meteorite, but the total system would be below freezing. The question is, does this simple thought experiment occur in nature? $\endgroup$ – tobias47n9e Apr 16 '14 at 15:02

Love & Brownlee (1991) put together numerical models for the experiences of micrometeorites entering the atmosphere. They say:

The peak temperatures experienced by submillimeter micrometeoroids rarely exceed 1700°C. Maximum temperature and mass loss rate generally occur at altitudes between 85 and 90 km during ∼1 sec of peak heating. A typical melted particle spends ∼2 sec at temperatures above the melting point.

Flynn (1989) discusses interplanetary dust, with figures for peak temperatures given in the abstract.

But I think that what you really want is Sears (1975), Temperature gradients in meteorites produced by atmospheric passage:

Temperatures in the order of 200°C have usually penetrated no further than 5-10mm, which is consistent with a luminous flight time of the order of 10s.

Using the geologists' rule of thumb for timescales of cooling (I believe $\tau^2 = \ell/\kappa$, where $\tau$ is the timescale, $\ell$ is the thickness of the cooling body, and $\kappa$ is the thermal conductivity - though it's a while since I've had to do this so I may be misremembering...), the information above about the height above the surface at which peak temperature is commonly reached, and an estimate of particle velocity, you can probably back-of-envelope a temperature for a meteorite on impact!


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