Mercury has a very elliptical orbit, but does it influence its temperature?

Submitted by legendsplayminecraft t3_11gx12z in askscience

I know why its hot in the summer and cold in the winter here in Earth and I also understand why Mercury has the most radical diurnally changes in its tempereture, but I cant find any information about the temperature changes caused by Mercurys elliptical orbit.

The orbit seems to be much more elliptical than Earths orbit, which is quite circular and doesnt play any role in weather or tempereture, because the distance from the sun doesnt vary that much.

But mercurys distance varies much more.

I mean, surely it could have an affect right?

If you can find a graph related to this, it would be awesome, but any calculations or things like that are fine too. I just don't know where to start, and google doesnt help either.

Thanks in advance!

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PlaidBastard t1_jarjsm1 wrote

The temperature does vary, but less than temps do just going from one part of Mercury to another.

  1. Mercury has no appreciable atmosphere. This means the temperature rises and falls very quickly in response to changing light levels/solar energy.

  2. Mercury rotates very slowly (59 days), so that heating remains extremely uneven.

So, on the dark side, it's actually probably close to the same exact temperature no matter where the planet is in its orbit. On the light side, it might be tens or more of degrees warmer when it's closer to the sun, but there's no global 'climate' to shift, if that makes sense?

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Kaipakta t1_jatf1se wrote

Yes!

To say, the difference in temperature relative to different points on its elliptical orbit on the side facing the sun range from: instantly overcook your pizza to... instantly overcook your pizza.

That being said- much like the nuclear explosion description, there is a spot on mercury's penumbra where the temperature is *perfect* for baking.

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babar90 t1_jaswwin wrote

Obliquity is very low. The irradiance is proportional to the squared distance, that means that the irradiance oscillates between x and 0.43 x depending on the season.

This is roughly equivalent to the seasonal irradiance oscillation that you'll have on earth at 45° latitude north.

But as PlaidBastard said this computation is meaningless, as the very slow rotation on Mercury makes the day vs night dominate the seasons.

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legendsplayminecraft OP t1_jatd5x3 wrote

how can you calculate that?

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babar90 t1_jatnibj wrote

Basic trignometry gives the irradiance curve, assuming that each region of the planet surface is disconnected from others (ie. no heat equation between day and night parts of the planet and whatever dominates its core temperature) and is at thermal equilibrium you can approximate the temperature with a constant time the 1/4th power of the irradiance

https://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law

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