NASA: Solar flares tear off tons of moon, Mars surface | Hacker News Reader

NASA: Solar flares tear off tons of moon, Mars surface

networkworld.com

12 pointscoondoggie7 comments

This reminds me of a discussion I had with a physicist recently. He insisted that the reason for Mars' atmosphere being gone was its low gravity. While it seemed reasonable to me that this could partly be a factor, I (intuitively) think the lack of a magnetosphere might play a bigger role in atmospheric loss. Did someone here by chance do some calculations that could help settle this argument?

(Note that the argument is NOT about smaller planet sizes leading to earlier magnetosphere failures. It's strictly about what leads to a greater rate of atmospheric loss: Mars' low gravity, or it's defective magnetosphere?)

This 2001 article basically says exactly what you're looking for. Where the magnetic field on Mars is stronger, there's a local ionosphere. Without a planetary magnetic field, solar winds blow away the atmosphere. http://science.nasa.gov/science-news/science-at-nasa/2001/as...

Yes, but I was looking for someone who maybe did a model on the quantitative effects of low gravity vs. low magnetosphere. There is no doubt that this effect exists (even my "opponent" conceded that), but I believe it's the dominant effect whereas some physicists apparently don't think so.

More specifically, all the material I can find seems to regard the lack of a magnetosphere as the dominant effect as well. Only this certain physicist suggested to me all this was a mere layman's explanation and that real astrophysicists "know" it's all about gravity instead. That kind of set off my bullshit alarm...

This article addresses that objection: even with the light mass, there's an ionosphere where there's protection from the magnetic field. If mass were the sole or primary contributor, then we'd see correlation with mass concentration rather than correlation with magnetic field.

Can you explain why Mars's magnetic field is so weak? Or why it is "defective"?

Because it doesn't have a liquid magnetic core that rotates in a way that creates a magnetic field. It's clear that at one point Mars did have a system similar to Earth's, but it stopped and nobody knows why. The theory is that one of the large collusions early in Mars' planetary formation caused surface heat that disrupted the convection of the magnetic dynamo. http://www.universetoday.com/30538/was-mars-magnetic-field-b...

So if a solar CME hits the moon when the moon is 'new', would some of that truckload hit earth? Certainly this has happened in the past. Wonder if this has been studied.

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