Alternate Planets, Suns, Stars, and Solar Systems Thread

any advice on positioning the day-night divide of a tidally locked world on a Winkel Tripel projection?
I think it depends on a couple of things. If the subsolar point (or an area within the inner hemisphere) is most habitable, and the rest is frozen, then you could put the terminator (day-night divide) at 90º E and W, so that the important areas are displayed in the center. If it's the region along the terminator in a narrow band that's habitable, maybe put the terminator along the equator line (0º N/S), with the subsolar point at one of the "poles".
If you don't have focus on any one region in particular, or if you want to highlight the whole world, both of these options are also good, but you might also consider placing your terminator at the prime meridian (0º and 180º E/W). Like the option of using the equator, this divides your map neatly in half into the day and night hemispheres.

It's also, of course, possible to use other projections.
 
Don't know if Universe Sandbox 2 images are good enough. But I played with the idea of Venus turning into a hotter TTL's Mars.
It would have a 24.36 sidereal rotation period. Roughly 0.9 bar atmosphere with +90% if it being Co². An axial tilt of around 25°. I think the mean temp. would be around 30°C. It's magnetosphere would look like a somewhat weaker version of Earth's.
I'd imagine this planet would be a muddy desert planet. So no to very little surface water but the earth itself is wet enough to support life thanks to subsurface lakes, rivers and all that.

Over all it would be a bigger and hotter version of Mars, and not the literal hell that is OTL's Venus.

Do you think this Venus could take Mars's place as the favorite child of scientific and public interest?
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Don't know if Universe Sandbox 2 images are good enough. But I played with the idea of Venus turning into a hotter TTL's Mars.
It would have a 24.36 sidereal rotation period. Roughly 0.9 bar atmosphere with +90% if it being Co². An axial tilt of around 25°. I think the mean temp. would be around 30°C. It's magnetosphere would look like a somewhat weaker version of Earth's.
I'd imagine this planet would be a muddy desert planet. So no to very little surface water but the earth itself is wet enough to support life thanks to subsurface lakes, rivers and all that.

Over all it would be a bigger and hotter version of Mars, and not the literal hell that is OTL's Venus.

Do you think this Venus could take Mars's place as the favorite child of scientific and public interest?
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Even if the magnetosphere is weaker than Earth's, a lot of the atmosphere would still have been blown off over billions of years since the solar wind is much stronger at Venus's location.

I'd think the life that evolves there (which would probably be related to Earth/Mars life via panspermia) would be useful in testing hypotheses regarding the early Earth before the emergence of the oxygen atmosphere.
 
Even if the magnetosphere is weaker than Earth's, a lot of the atmosphere would still have been blown off over billions of years since the solar wind is much stronger at Venus's location.
If that’s true, since Venus’s atmosphere is 90 bar right now, how much thicker was it eons ago, then?
 
Wait, so Venus back then had around 340 bar?
If we evaporate Earth Ocean and decompose carbonates by heating we would have near 320 bar in Earth


Wonder how much that would increase the temp.
I don't know. And we should remember that a disproportionately large part of Venus' atmospheric loss is water, which is greenhouse gas too



Over all it would be a bigger and hotter version of Mars, and not the literal hell that is OTL's Venus.
Is this clouds in south hemisphere? ATL Venus should be pretty dry, because wet Venus with fast rotation will have runaway greenhouse effect by water.
 
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If we evaporate Earth Ocean and decompose carbonates by heating we would have near 320 bar in Earth



I don't know. And we should remember that a disproportionately large part of Venus' atmospheric loss is water, which is greenhouse gas too




Is this clouds in south hemisphere? ATL Venus should be pretty dry, because wet Venus with fast rotation will have runaway greenhouse effect by water.
So dry and thinner atmosphere are more likely with OTL Venus orbit?
 
So dry and thinner atmosphere are more likely with OTL Venus orbit?
It depends from first off all magnetosphere, temperature and initial composition of planet.


Roughly 0.9 bar atmosphere with +90% if it being Co².
I thought again and I have doubts. I not sure that 0.8 bar CO2 don't warm planet by greenhouse effect. And ATL Venus atmosphere should have more Nitrogen. OTL Venus nas 3 bar N2 and Martian N2 escaped or turned into nitrates
 
It depends from first off all magnetosphere, temperature and initial composition of planet.



I thought again and I have doubts. I not sure that 0.8 bar CO2 don't warm planet by greenhouse effect. And ATL Venus atmosphere should have more Nitrogen. OTL Venus nas 3 bar N2 and Martian N2 escaped or turned into nitrates
Maybe 1/3 Co² like pre life Earth?
 
Maybe 1/3 Co² like pre life Earth?
It is not the thing I can calculate on a napkin. We need to take into account Venudune's surface radiation spectrum and CO2 absorption window.
Venus with Martian albedo already has 304K effective temperature. So, on first look, Venudune's atmosphere should have pretty little of greenhouse gases but as I said it need more calculations
 
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