Be Excellent To Each Other

Hey clever Beex peeps, help a hapless old wannabee out here please?

Loads of things perplex me in real life (no, not going to the toilet), but science type stuff more than most. Some things just don't seem to make any sense whatsoever to me.

Astronomy has long held a fascination for me personally, from the earliest possible age. I was painting Red Giant stars in reception class (well, "Red Gant" IIRC, my spelling hasn't progressed much), when all the other kids were rendering mummy and daddy. Yeah, sad I know. Anyway, there are so many things I could ask, but to kick things off (hopefully ), there is one matter that springs to mind.

1. Venusian Atmosphere

We're always being told that the Earth relies heavily on its magnetic field (and hence active, liquid metallic core) to avoid high energy cosmic rays from the sun gradually pinging off (yep, that's a technical term) the atmosphere. Seems fair enough to me; the physics isn't difficult to understand (at my elementary level), and Mars is often cited as what happens if there's an absence of this magnetic field. (We're told that in the case of Mars, the CO2 atmosphere is only c.1% that of the Earth's in barometric pressure terms, but that it once held a much thicker atmosphere sufficient to allow liquid water to exist on the surface and had an active core). I appreciate, of course, that Mars has a rather lower mass than the Earth, which does account for the thinner atmosphere to some extent, but that mass must've by definition been sufficient to capture and retain the once thicker atmosphere, and it's hardly as though Mars has lost any of its mass. After all, plenty of Jovian and other gas giant moons of comparable or less mass have thick atmospheres (e.g. Titan).

So far, so good. But, Venus has a super-thick largely CO2 atmosphere that's 90 times the barometric pressure of the Earth (and hence fully 9,000 times that of Mars), despite having no more mass than the Earth, and most crucially of all - no magnetic field to speak of AND it is much closer to the Sun (and hence those nasty cosmic rays).

How is this possible? One would surely expect Venus to lose its atmosphere in short order?


Hmmm.

From what I know the lack of a strong magnetic field on Venus has contributed to the run-a-way green house effect. lighter gasses (like hydrogen and helium) have pinged away, leaving the heavier gases, the greenhouse gases like co2, methane etc to dominate.

God made it like that.

Not sure about anything else but I'm sure the current theory is that Mars overall mass wasn't quite large enough to keep its internal core molton. Over time it cooled and the magnetic field it had to hold the sun's rays from striping the atmosphere didn't quite do the job it used to. Earth is big enough to keep it core molton and cools more slowly keeping us with a thinker atmosphere.

Or something like that anyway.

Also Wikipedia has this:

Unlike Earth, Venus lacks a magnetic field. Its ionosphere separates the atmosphere from outer space and the solar wind. This ionised layer excludes the solar magnetic field, giving Venus a distinct magnetic environment. This is considered Venus's induced magnetosphere. Lighter gases, including water vapour, are continuously blown away by the solar wind through the induced magnetotail.[4] It is speculated that the atmosphere of Venus up to around 4 billion years ago was more like that of the Earth with liquid water on the surface. A runaway greenhouse effect may have been caused by the evaporation of the surface water and subsequent rise of the levels of other greenhouse gases.[8][9]

I don't think the lack of magnetic field has any bearing on the greenhouse gas effect mate; this would be the case irrespective. I did think about the heavier molecules of CO2, though, but there again, Mars' atmosphere is composed chiefly of the same gas, albeit with lower gravity, but much less intense solar radiation also. Weird.

Edit: actually, you're probably onto something mate, see below.

(Actually, it turns out that Science is at a loss as to why Venus should be so hot, even allowing for the immense greenhouse gas effects, but that's another story I guess)

Cheers Zarz, that clears that up, then!

That's very interesting mate, thanks.
So basically, although there's no magnetic field induced by a mobile metallic planetary core, the ionosphere essentially does the same job by protecting lower atmosphere layers (and heavier molecules as Malc alludes to in his post?)

That's what I made of it, yes. Although it seems it's still a long way off being fact.

Hey, what we really need is a Gaywood and a Lave to help us out here.
Let's see if this works:


1. GAMES CONSOLES SUCK, I USE A PC

2. SCIENTOLOGY AND HOMEOPATHY ARE TEH AWESOME

/waits

Half-right. Once you become 'clear' you no longer need treatments, homeopathic or otherwise.

Solar wind interacts with ionosphere inducing a magnetic field, innit,

You could direct this question to Neil DeGrasse-Tyson, the friendly astrophysicist who hosts the StarTalk radio podcast. They have accounts on all the social platforms which are easy enough to find and they do regular podcasts answering "cosmic queries" such as this. It's quite pop' sci' and usually quite entertaining if you feel like subscribing. In fact I believe the whole Martian atmosphere question has been discussed before and iirc it is to do with solar winds stripping the planet.

I'm not sure he's a member.

Many thanks for the tip, DBSnappa.
Sounds like my bag, I'll check it out!

I'be been in high impact journals doncha know?