The Astronomy Thread

[Dan Wyatt]

PBS Spacetime did an episode on the Venus phosphine detection, and speculated on what forms Venusian life might take. They address my principal criticism, which is that while evolved microorganisms might be able to enter some kind of inert spore phase to survive the times when atmospheric circulation takes them out of the narrow habitable zone, it would be almost impossible for the first basic life forms to originate in such an environment. They concede this point and point out something that hadn't occurred to me, which is that Venus probably had an Earth-like phase in its early history, before the runaway greenhouse effect turned it into a hellzone. Life might have been able to originate on the surface in conditions similar to those on Earth, and then evolved to adapt to survival in the upper atmosphere as it slowly got hotter and denser (and more acidic) over time.

Venus is unlikely to harbor lifeforms. It's surface temperature is around 700K, that will vaporise any living cellular walls. Also upper atmosphere is subjected to UV radiation and gas escape to space due to solar wind pressure.

[Arioch]

Launch of a Soyuz Progress as seen from ISS

[Werra]

Looks like 2020 will close on a high note.

https://nypost.com/2020/12/04/milky-way ... lack-hole/

SpoilerShow

Yes, the article doesn't support the headline at all. But that's journalism for you.

[icekatze]

hi hi

Usually, when confronted with bad science journalism, I try to find the source instead.

It seems that us humans still have a long way to go before we can have good confidence in interstellar motion and distances.

[Arioch]

And, unrelated:

A photo from orbit of the Moon's Ocean of Storms, which is the landing site for the Chinese Chang'e-5 lander. It striking to see the sharp transition from the lighter, older surface to the darker, newer surface which apparently flowed out from the volcano to the left. And what looks like some sort of channel to the upper right. I wonder whether it was a feature created by the flow of the molten lava, or something carved afterward by flowing liquid... maybe water that condensed from steam released by the lava.


https://apod.nasa.gov/apod/ap201205.html

[Mjolnir]

And what looks like some sort of channel to the upper right. I wonder whether it was a feature created by the flow of the molten lava, or something carved afterward by flowing liquid... maybe water that condensed from steam released by the lava.

I think that's Rima Mairan/Mairan Rille:
https://en.wikipedia.org/wiki/File:Rima ... -12870.jpg
https://www2.lpod.org/wiki/May_26,_2006

It's not clear what formed these rilles, but most of the proposed explanations seem to involve flowing lava. It'd take a lot of water.

[Arioch]

Yes, a collapsed lava tube does make more sense.

I can easily imagine that such a large amount of magma could release enough water to form a river, but in order for it not to boil away immediately, there would have to be so much steam that it would form a temporary atmosphere... and that is a bit more far-fetched.

[boldilocks]

You "magma is sentient and can build channels" conspiracy theorists can think what you want,
but I'm gonna stick with the science and say that this is clearly the work of aliens.

[GeoModder]

You "magma is sentient and can build channels" conspiracy theorists can think what you want,
but I'm gonna stick with the science and say that this is clearly the work of aliens.

An alien latrine dugout?

[icekatze]

hi hi

While it is still too early to be confirmed, it looks like astronomers have found signs of a potential Neptune sized planet in the habitable zone of Alpha Centauri A.

The news article overview
The scientific paper

[Ithekro]

I wonder about how common gas giant sized planets are in the habitable zones of stars. All ours are well outside that zone. Terrestrial planets that we are aware of would be theoretically smaller, though a giant dirt ball is possible I suppose. What sort of life could live there?

[icekatze]

hi hi

Giant planets in close orbits around stars are turning out to be pretty common in the nearby universe. And some models of solar system formation suggest that the giant planets in our own solar system may have moved around from their original locations.

Even if it'd be exceptionally difficult to have life on a warm neptune (microbial life... not strictly impossible...) who knows what could happen if it has moons.

Probably still too early for any kind of speculation.

[Ithekro]

Given our space flight technology...its going to take a very long time to find out. Without an FTL drive or other means of jumping to another star system, a probe will take decades to centuries to reach even the Alpha Centauri system. Even with a theoretical 0.1 times the speed of light probe it take nearly half a century to get there. Our governments are not into that kind of long term planning/missions, as it does not benefit them or their associates directly, and might not even benefit their next of kin or even grandchildren, if the mission takes a century to even attempt a round trip (Queen's song "'39" comes to mind) And even a one-way mission will have communications issues just getting the data back to the Sol System.

[GeoModder]

Even if it'd be exceptionally difficult to have life on a warm neptune (microbial life... not strictly impossible...) who knows what could happen if it has moons.

[Dan Wyatt]

Even if it'd be exceptionally difficult to have life on a warm neptune (microbial life... not strictly impossible...) who knows what could happen if it has moons.

Humanity should have owned blue skin xenos, instead we got some Disney tier ending.

[GeoModder]

Humanity should have owned blue skin xenos, instead we got some Disney tier ending.

Fighting a whole world 4,35 light years away from home? I don't think so.

[Arioch]

Phosphine detection on Venus debunked:

[icekatze]

hi hi

Phosphine detection on Venus debunked:

Ah, that's a pity. But that's deep space observations for ya. One day you think you've found a smoking gun, the next it turns out to be an error with the data set.

[Arioch]

[Dan Wyatt]

Humanity should have owned blue skin xenos, instead we got some Disney tier ending.

Fighting a whole world 4,35 light years away from home? I don't think so.

Should have nuked them from orbit, them and their trees.