Parker Solar Probe Captures its First Images of Venus' Surface in Visible Light, Confirmed (Looks like full of 860 degree 'water')

NASA ^ | 2/9/22 | NASA

[melancholy]

I would weigh 1800 lbs on Venus

Assuming you weigh 200 lbs., you would weigh 182 lbs. on Venus, @0.91 earth gravity.

Weight is a function of gravitational force not pressure.

[Yollopoliuhqui]

860 degrees!!? Calling Dr. Velikovsky...

[calenel]

“Venus is about the size of our earth. Why would atmospheric pressure there be great enough to have liquid water at 800 degrees?”

Because so much water vapor is in the atmosphere. Based on the pressure we can calculate that there is about a kilometer’s depth of water across the globe suspended in the atmosphere.

I don’t know what the land-water ratio of Venus would be if that water were surface water, probably very low, now, since Venus has been largely scoured flat, but imagine if Earth’s oceans were a mile lower (30% land on Earth, ball parking the depth) and all that water was in the atmosphere.

Also, there is this thing called liquid-vapor equilibrium. Depending on temperature and pressure there will be various proportions of liquid or vapor (technically, solid, too, but not in amounts relevant to this discussion). Temperature increase moves the ratios toward the gas end, pressure increase toward the liquid (solid) end.

So, yes, if there is enough water on Venus, even at 860 degrees, there would be liquid water.

And that is also why deflategate was a bogus scandal.

[calenel]

I would say both, and it is wrong, anyway.

[Magnum44]

Please elaborate. When you say wrong, you mean the internet comment? As someone who has spent his second career in spacecraft design and operations, it was interesting to me that Venus has nearly our gravity, but two orders of magnitude difference in surface atmospheric pressure, yet also has no mag field to speak of. Why is the atmosphere not stripped away like mars?

The only thing I can think of is that the atmosphere is very heavy with moisture (I dont know if that means H2O, or some other liquid element) that it has some heavy liquid properties but also gas properties. Too heavy to be swept away by solar wind. Like most, I am fascinated by the planetary sciences, but its not been my specialization.

[atc23]

Oh! Thank you! The Venus diet!

[dangus]

>>>> Mars is both significantly smaller, and has far, far LESS atmosphere than Earth. <<<<

>> Why? <<

Why is it smaller? I don’t know that we know or don’t know.

Why does it have less atmosphere? Probably being further from Earth and further from the Sun, it encountered less gasses to pull toward itself, and did a poorer job of keeping those gasses that it did encounter.

[null and void]

Probably being further from Earth and further from the Sun, it encountered less gasses to pull toward itself

Like Jupiter, Saturn, Neptune, and Uranus?

[calenel]

The evolution of CO2 in Venus’ atmosphere, according to the quote you posted, is incorrect. It’s just alarmist nonsense.

Venus is a lot more massive than Mars so all other things being equal (they’re not) it would lose its atmosphere much more slowly. Being further away from the Sun, Mars’ atmosphere would be on average composed of lighter gases and easier to displace. Molecular velocities are normally distributed and the mean is, among other things, a function of mass (weight). Pressure is a linear function, but still, most of the atmosphere is within a few miles of the surface. And Venus is still (likely) volcanically active, so there is some outgassing. It has lots of volcanoes (mostly inactive, now). More than any of the other planets.

Given that Venus does not have a magnetic field, it likely no longer has a molten outer core, but given that it is close to the Earth in size, it likely did until relatively recently in geological time. Perhaps that is the most significant reason it still has a substantial atmosphere.

In any case, there are lots of reasons that Venus hasn’t lost its atmosphere to the Solar Wind quite yet.

[Magnum44]

Thanks, interesting that:

it likely no longer has a molten outer core

but is still has volcanic activity.

Also brings these questions to mind -

1) Does the mag field require molten outer core or can an inner core suffice? I did some Earth mag field modeling at one time, but its all about models (multiple dipoles or spherical harmonics developed empirically from measurements) and is not necessarily representative of the real physics.

2) Related to your outer core comment and my first question, I presume the planet cools from the outside in, given the pressures near the core. So not being a geophysicist, its still confusing that there is volcanic activity but a cold outer core.

3) Finally, some motion of the 'lava' containing the ferrous material is necessary for the mag field to be sustained. Is it possible there is no ferrous material in that inner or outer core?

[Sicon]

Science! Well done.

[null and void]

Thank you for taking the question seriously.

I’m hoping to someday get the answer. I have a couple unpalatable theories of my own.

[null and void]

In any case, there are lots of reasons that Venus hasn’t lost its atmosphere to the Solar Wind quite yet.

Let's hear them.

Seriously. I've been raising the Mars lost its atmosphere due to weak solar wind and no magnetic field vs Venus has an amazingly thick atmosphere, and stronger solar winds, and no magnetic field question.

[BiteYourSelf]

Probably because Venus is the remains of a gas giant.🤔

[calenel]

It likely no longer has a molten outer core, else there would be a magnetic field. That does not mean it’s cold, though. If the core were hot enough to still be liquid, convection currents, crystallization, and even tidal forces on the molten metal would contribute to generating a magnetic field. The entire core could be molten or just the outer core - I am basing on the Earth model of a dual core with the inner core solid, but that isn’t required.

There is likely some residual volcanic activity as long as the mantle and core have not cooled completely. Remember, the mantle flows plastically under great pressure and less dense material rises. As it approaches the surface the pressure decreases. Melting occurs, and you get volcanoes, eruptions, outgassing. So, yes, the planet cools from the outside in due to radiation, but there is residual heat working its way out.

Once the core solidifies its way to the nonmetallic layer the mag field dies. The Mantle is presumed to be “solid” (plastic) already, but without high metal content it isn’t going to generate a magnetic field, anyway.

[calenel]

“Let’s hear them.”

I just gave a bunch of them in the post you replied to.

But I’ll summarize what I think is probably the most significant one - Venus likely only lost its mag field recently (geological time recently). It has not had time to lose its atmosphere, while Mars cooled long, long ago (being much smaller and gravitationally weaker) and has had the time.

[Jonty30]

Maybe so, I don’t think it would rise under that pressure.

[null and void]

Thank you.

[calenel]

If there were no water already in the atmosphere, you’d be right, but the effect of the already-evaporated water suspended in the atmosphere pushes back on the liquid-phase water and keeps it from boiling off.

That’s why there is still water in liquid phase on Earth at 100% humidity - the atmosphere is saturated. Max water in the air on Earth is about 4%.

That is not to say that there MUST be liquid water on Venus, only that there COULD be, even at that temperature.

[aquila48]

RELATIVE humidity is a function of temperature. The higher the temperature the more water vapor the atmosphere can hold, which causes the atmosphere to become denser and thus cause a higher pressure. It’s why the atmospheric pressure is so high in venus.

Its atmosphere is not 100% saturated at 820 degrees F, thus it does not rain down and thus no liquid water. Any droplet that might form would be immediately evaporated.