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First Exo-Planet with water!

PhantomWolf

Penultimate Amazing
PhantomWolf
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https://www.space.com/alien-planet-k2-18b-water-vapor-not-earth-twin.html

Water vapour has been detected in the atmosphere of a super-Earth with habitable temperatures by UCL researchers in a world first.

K2-18b, which is eight times the mass of Earth, is now the only planet orbiting a star outside the Solar System, or 'exoplanet', known to have both water and temperatures that could support life.

Sadly we aren't going to be visiting anytime soon, first off, it's about 8x as massive as Earth, and second, it's 111 light years away.
 
Eight times, Yikes. I thought it was only twice the size of Earth.

I hope we get new data soon. Could be fun stuff.
 
Skeptic Ginger said:
Eight times, Yikes. I thought it was only twice the size of Earth.

I hope we get new data soon. Could be fun stuff.
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Trebuchet said:
If it's twice the diameter, that implies eight times the mass. Two cubed, and all that. Your density may vary.
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Yep

The formula for the volume of a sphere is 4/3πr3
Double the diameter of a sphere, and the volume goes up by 8 times

10m diameter sphere = 524 m320m diameter sphere = 4188 m340m diameter sphere = 33510 m3

When you start cubing stuff, the numbers get very big, real quick!
 
If it's twice the diameter, 8 times the mass, and (big if) the same average density of earth, then the surface gravity would be twice that of earth. If gravitational compression has reduced its radius and increased its density, then the surface gravity would be higher.
 
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Cheetah said:
I wonder what life would look like if it evolved there.
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What does the life that evolved on earth "look like"? It varies a bit. There are petunias and there are kangaroos. The life on the other planet may look something like these.

But I would love to see alien living organisms. To my mind, whether or not life exists elsewhere is by far the most interesting outstanding mystery.
 
smartcooky said:
When you start cubing stuff, the numbers get very big, real quick!
Click to expand...

Yes, this is true, but each increase puts you further way from the centre of gravity, which obeys an inverse square law. For objects of equal density, surface gravity varies in proportion with radius.
 
smartcooky said:
Yep

The formula for the volume of a sphere is 4/3πr3
Double the diameter of a sphere, and the volume goes up by 8 times

10m diameter sphere = 524 m320m diameter sphere = 4188 m340m diameter sphere = 33510 m3

When you start cubing stuff, the numbers get very big, real quick!
Click to expand...

This is why a 3L bottle of Coke doesn't look much bigger than a 2L bottle of Coke.
 
Something that is absent, understandably, from press reports on the subject is how they detected the water.

Are they sure? It's my understanding that exoplanets are detected by noting periodic variations in starlight as planets occlude their suns. How would this method allow you to determine the chemical composition of the planet and its atmosphere?
 
Craig B said:
What does the life that evolved on earth "look like"? It varies a bit. There are petunias and there are kangaroos. The life on the other planet may look something like these.

But I would love to see alien living organisms. To my mind, whether or not life exists elsewhere is by far the most interesting outstanding mystery.
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I think if there is complex life there is a lot you could speculate about, for example.

Carbon based.
Probably uses the same 20 amino acids as here if not all of them.
Something very similar to DNA & RNA if not exactly.
Made of cells.

If there are free swimming animals:
Bodyplan basically a tube with a mouth on one end and a pooper on the other.
Bilaterally symmetrical.
There is a lot more stuff like this.


Certain things just work better and it's likely evolution and chemistry will solve similar problems in similar ways.
I think it's quite likely alien 'fish' in similar niches to earth fish might look superficially very similar. Having a streamlined body with a flat tail on one end, to propel itself forward, and a mouth on the other end is just the best design.
 
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Cheetah said:
Probably uses the same 20 amino acids as here if not all of them.
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That is excessively unlikely.

There are over 100 amino acids, I think. That any one set of carbon-based life would use the same combination we use is very very improbable. That's the main reason why we know that all life on Earth today descends from the same unique cell.
 
Belz... said:
That is excessively unlikely.

There are over 100 amino acids, I think. That any one set of carbon-based life would use the same combination we use is very very improbable. That's the main reason why we know that all life on Earth today descends from the same unique cell.
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They are not equal though. A whole mix was available and life 'chose' a few. Amino acids need to link together to form peptide chains to form more complex structures. Some amino acids form chains more readily and more efficiently. The best ones were selected for.


Why does all life use the same 20 amino acids?
 
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Meadmaker said:
Something that is absent, understandably, from press reports on the subject is how they detected the water.

Are they sure? It's my understanding that exoplanets are detected by noting periodic variations in starlight as planets occlude their suns. How would this method allow you to determine the chemical composition of the planet and its atmosphere?
Click to expand...

They looked at the star light as the planet passed in front of the star and noted what absorption was occurring, because water and other chemicals absorb certain parts of the spectrum. Water has a very distinctive absorption in the IR part of the spectrum, so by looking at the light before and comparing it to that as the planet passes, if you see the absorption of those frequencies in the IR part of the spectrum, then you can say that the starlight had to pass through water, and the only source of that water is the planet.
 
I didn't see mentioned ... would not the gravity of that planet preclude humans settling there ... could a landing party leave the planet (due to the increased escape velocity needed)

Realistically even a small increase in gravity, would cause a human's blood to pool in the legs, creating numerous medical problems.
 
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