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Old 03-21-2019, 07:55 PM
 
Location: Pennsylvania, USA
419 posts, read 295,553 times
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Totally random questions relating to space coming from an amateur space nerd. Feel free to answer as many as you want!

1. How is Venus able to hold down such a massive atmosphere if its gravitational force is less than the Earth's (consider Venus has no magnetosphere and is hit by much stronger solar winds which should have stripped its atmosphere by now)? Everything here seems to point to Venus's slow rotational speed and lack of tectonic plates and subduction processes. Is that it then? So, why isn't the Earth a fiery ball of runaway greenhouse gases like Venus with its stronger gravitational force, magnetosphere, and further distance from the sun? Do we know if Venus's atmospheric pressure has changed at all over the years? Could we siphon its atmosphere into space somehow (I am guessing no...?)?

2. How are we so sure there are 100's of billions of galaxies (an ambiguous guess)? Perhaps our universe is a 4D hypersphere, and if you went straight long enough you would return to the starting point. Picture the universe as being shaped like a doughnut or a long tunnel where everything just repeats. Perhaps many so-called galaxies are simply repeater multiple times (like two mirrors bouncing off each other). Can we use AI to 'count' the actual number of distinct galaxies, and/or search for duplicates/patterns recurring in space? It would be useful to more tightly quantify a range of the number of galaxies and apply it toward universal Drake equation.

3. Will we ever be able to study and understand other solar system exo-planets remotely with more advanced Earth orbit-based telescopes, and obtain a similar understanding of exo-planets that we have about the planets in our own solar system? (i.e. size, surface temperature, atmospheric composition, atmospheric pressure, planet-wide weather, magnetic field, gravitational force, length of day, surface features, moons, habitability). I suppose many of the aforementioned conditions were gathered from probes and rovers rather than telescopic observations? Not that it makes any difference since we could never send humans to another star with today's technology. It would be beyond interesting to discover and observe another Earth-like planet, if one exists, and compare it to our own world.

4. How can we be so sure Mars has frozen water in its polar ice caps, and that its ice caps are not just entirely composed of frozen CO2 instead? Does Mars really have useful quantities of frozen water to support human colonization, or are we still uncertain about this? Why is water nowadays so rare on other bodies in our solar system, while the Earth is awash with water? (perhaps this is due to the early development of our solar system and the Earth itself)

5. Other than Earth, what planet/moon in our solar system would you survive longest on? My guess would be Mars, perhaps you would survive for a minute at best. Slightly morbid question.

6. Which planet or moon would you like to know more about and why? What would you be surprised to learn based on our current theories about said planet or moon?

I know these questions are all unrelated and may seem stupid, I was just wondering everyone's thoughts and wanted to have a discussion.

Last edited by g500; 03-21-2019 at 08:45 PM..
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Old 03-22-2019, 09:00 AM
 
5,825 posts, read 3,582,291 times
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Originally Posted by g500 View Post
4. How can we be so sure Mars has frozen water in its polar ice caps, and that its ice caps are not just entirely composed of frozen CO2 instead?
I'll try and take a shot at this one. I think that CO2 freezes at -78.5°C, or -109.2°F, so if the poles get warmer than that temperature, the CO2 (if it's there) will start to change state. You would need to use a phase diagram of CO2 and know the temps and atmospheric pressure at the Martian poles.

I would guess that while it's still cold at the poles it does get warmer than -78.5°C, therefore it's most likely water?
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Old 03-22-2019, 02:15 PM
 
Location: Seattle
2,295 posts, read 490,180 times
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1. How is Venus able to hold down such a massive atmosphere if its gravitational force is less than the Earth's (consider Venus has no magnetosphere and is hit by much stronger solar winds which should have stripped its atmosphere by now)? Everything here seems to point to Venus's slow rotational speed and lack of tectonic plates and subduction processes. Is that it then? So, why isn't the Earth a fiery ball of runaway greenhouse gases like Venus with its stronger gravitational force, magnetosphere, and further distance from the sun? Do we know if Venus's atmospheric pressure has changed at all over the years? Could we siphon its atmosphere into space somehow (I am guessing no...?)?
Note that Venus has very little hydrogen left in its atmosphere, so that lightweight atom has already been stripped by the solar wind. The gravity of Venus is only slightly less than Earth's, so the gravitational retention is similar. Carbon dioxide is much heavier than hydrogen, so each atom has a far lower probability to be driven to reach escape velocity by the solar wind. Thus, stripping the CO2 atmosphere away from Venus will take much longer than just removing the hydrogen.

As the temperature of the Sun rises, Earth will have a runaway greenhouse atmosphere in the future (c. a billion years from now). The current thermal energy from the Sun at Earth's orbital distance is just too low right now.

Presumably you could use something like a space elevator to siphon off the gas from, Venus; perhaps it could be moved to Mercury for dumping? Or perhaps you could convert the carbon into diamonds, which is stable to 750 F? Not sure about that though. The extra oxygen you dump into the atmosphere will probably oxidize it back to CO2. Possibly you could park an enormous sun screen at the L1 Lagrange point to cool down the atmosphere first, so the surface can oxidize. But that will take millions of years.
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Old 03-27-2019, 09:54 AM
 
22,779 posts, read 17,257,359 times
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Originally Posted by g500 View Post
Totally random questions relating to space coming from an amateur space nerd. Feel free to answer as many as you want!



3. Will we ever be able to study and understand other solar system exo-planets remotely with more advanced Earth orbit-based telescopes, and obtain a similar understanding of exo-planets that we have about the planets in our own solar system? (i.e. size, surface temperature, atmospheric composition, atmospheric pressure, planet-wide weather, magnetic field, gravitational force, length of day, surface features, moons, habitability). I suppose many of the aforementioned conditions were gathered from probes and rovers rather than telescopic observations? Not that it makes any difference since we could never send humans to another star with today's technology. It would be beyond interesting to discover and observe another Earth-like planet, if one exists, and compare it to our own world.



I know these questions are all unrelated and may seem stupid, I was just wondering everyone's thoughts and wanted to have a discussion.
We are already able to determine the atmospheric composition of some exo-planets.

GRAVITY instrument breaks new ground in exoplanet imaging
Cutting-edge VLTI instrument reveals details of a storm-wracked exoplanet using optical interferometry
Date:
March 27, 2019


''The GRAVITY instrument on ESO's Very Large Telescope Interferometer (VLTI) has made the first direct observation of an exoplanet using optical interferometry. This method revealed a complex exoplanetary atmosphere with clouds of iron and silicates swirling in a planet-wide storm. The technique presents unique possibilities for characterising many of the exoplanets known today.''

''This is the first time that optical interferometry has been used to reveal details of an exoplanet, and the new technique furnished an exquisitely detailed spectrum of unprecedented quality -- ten times more detailed than earlier observations. The team's measurements were able to reveal the composition of HR8799e's atmosphere -- which contained some surprises.''

Read more: https://www.sciencedaily.com/release...0327080721.htm
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Old 03-28-2019, 02:43 PM
 
Location: Seattle
2,295 posts, read 490,180 times
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2. How are we so sure there are 100's of billions of galaxies (an ambiguous guess)? Perhaps our universe is a 4D hypersphere, and if you went straight long enough you would return to the starting point. Picture the universe as being shaped like a doughnut or a long tunnel where everything just repeats. Perhaps many so-called galaxies are simply repeater multiple times (like two mirrors bouncing off each other). Can we use AI to 'count' the actual number of distinct galaxies, and/or search for duplicates/patterns recurring in space? It would be useful to more tightly quantify a range of the number of galaxies and apply it toward universal Drake equation.
If that were true, we'd still be looking at galaxies from different directions and at different times in their life span, so there'd be no way to confirm it with 100% certainty. But I think you can just apply Occam's razor to the question -- the current view is well-explained by a geometrically flat space-time topology. There's no need to think up more complex scenarios to explain it.
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