Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Webb Discovers Methane, Carbon Dioxide in Atmosphere of K2-18B

nasa.gov

Post reply on HN
Print view View original

51–60 of 142 posts

Re: Webb Discovers Methane, Carbon Dioxide in Atmosphere of K2-18B

#51

Post by colechristensen »

behnamoh wrote: post #24
v8xi wrote: post #14

In Nick Lane's Oxygen: The Molecule that Made the World, he talks about the importance of both methane and carbon dioxide and how they exist at the extremes of a complex metabolic oxidation-reduction cycle. Methane stores a lot of chemical energy in its C-H bonds which can be burned directly, or metabolized through repeat oxidation events to ultimately form CO2, which plants utilize with the help of the sun to form m…

I wonder what life looks like on a planet which is over 8 times more massive than the Earth. Do animals have spines at all on a planet with almost 8g gravity? Does life even get to evolve into complex systems like animals under this much gravity? How about plants? Do they grow up or spread out instead? If one day we get a visitor from this planet, they'll jump on our planet the same way human astronauts jumped on the…

As others have mentioned it wouldn't be 8 g. Life would be smaller. There would be speed differences. A lot of optimums and limits depend on how volume scales against area. Like the biggest terrestrial animals are limited a characteristic dimension (height or length) x being proportional to femur area x^2 being proportional to mass x^3. Mass grows proportional to x^3, femur strength (area) grows proportional to x^2, so you have a limit on how big a thing can be when you run out of available femur strength.

Higher gravity means this upper limit will be smaller. All sorts of similar scaling things will change optimum points for structural and energy reasons.

Re: Webb Discovers Methane, Carbon Dioxide in Atmosphere of K2-18B

#52

Post by jandrese »

BoiledCabbage wrote: post #35
Aachen wrote: post #21

Earlier quoted context omitted.

Wow, that's really close so far as these things go. With the nearest star being 4ly, this can be reached with essentially the same tech level if we'd want to visit that with a rover or generational ship one day

What's also crazy is if we did send a rover over there to hunt for life, and they found it, we'd have to wait 125 years to hear the result. We all sit around knowing to listen to the skies sometime in October of 2185 to hear if the rover found life within the first month of its landing. If we ever send a team to live there, we'd hear broadcasts of their lives from 125 years prior. A real portal in time - so cool.

Even worse if we are still limited by Newtonian dynamics it will take thousands of years for a probe to reach there. The rocket equation is a harsh mistress. In practical terms we will never visit that world without completely upending physics as we know it.

Re: Webb Discovers Methane, Carbon Dioxide in Atmosphere of K2-18B

#53

Post by pdonis »

behnamoh wrote: post #24
v8xi wrote: post #14

In Nick Lane's Oxygen: The Molecule that Made the World, he talks about the importance of both methane and carbon dioxide and how they exist at the extremes of a complex metabolic oxidation-reduction cycle. Methane stores a lot of chemical energy in its C-H bonds which can be burned directly, or metabolized through repeat oxidation events to ultimately form CO2, which plants utilize with the help of the sun to form m…

I wonder what life looks like on a planet which is over 8 times more massive than the Earth. Do animals have spines at all on a planet with almost 8g gravity? Does life even get to evolve into complex systems like animals under this much gravity? How about plants? Do they grow up or spread out instead? If one day we get a visitor from this planet, they'll jump on our planet the same way human astronauts jumped on the…

The planet's surface gravity is not 8 g. Surface gravity goes like mass over radius squared, and the planet's radius is 2.6 times Earth's, so the surface gravity will be 8 / (2.6)^2, or only about 1.2 times that of Earth.

Re: Webb Discovers Methane, Carbon Dioxide in Atmosphere of K2-18B

#55

Post by alexpotato »

behnamoh wrote: post #24
v8xi wrote: post #14

In Nick Lane's Oxygen: The Molecule that Made the World, he talks about the importance of both methane and carbon dioxide and how they exist at the extremes of a complex metabolic oxidation-reduction cycle. Methane stores a lot of chemical energy in its C-H bonds which can be burned directly, or metabolized through repeat oxidation events to ultimately form CO2, which plants utilize with the help of the sun to form m…

I wonder what life looks like on a planet which is over 8 times more massive than the Earth. Do animals have spines at all on a planet with almost 8g gravity? Does life even get to evolve into complex systems like animals under this much gravity? How about plants? Do they grow up or spread out instead? If one day we get a visitor from this planet, they'll jump on our planet the same way human astronauts jumped on the…

The book Dragon's Egg has a species living on a neutron start with millions of G's

https://en.wikipedia.org/wiki/Dragon%27s_Egg

Re: Webb Discovers Methane, Carbon Dioxide in Atmosphere of K2-18B

#57

Post by treyd »

julienchastang wrote: post #13
kaycebasques wrote: post #9

It's mind-bendingly cool that people can figure out the composition of an atmosphere without actually being close to that atmosphere. Had not heard of dimethyl sulfide before. That's a good keyword to know.

From a single pixel of light! Indeed mind blowing.

That's somewhat misleading though. It's not really a pixel in that there's much more information available than, basically, 3 integers between 0 and 255. There's 4 instruments on the telescope that collect 4 different chunks of IR spectra, and there's very precise and granular intensity values for light received around any given wavelength. Much more detail than a "pixel" has in the typical sense we use them.

It's not a lot of information, not nearly enough to identify surface features on an exoplanet, but it's very useful data if you're trying to identify likely chemical composition of bodies or how hot clouds of gas are.

Re: Webb Discovers Methane, Carbon Dioxide in Atmosphere of K2-18B

#59

Post by no_wizard »

delta_p_delta_x wrote: post #16
unsupp0rted wrote: post #8

Earlier quoted context omitted.

> Complex animal life took 3.5 bn years to emerge on Earth, How certain are we it took that long (the first time)?

The fossil record. There is little evidence of very complex animal life before about 541 million years ago, which is when the Cambrian explosion begun.

When you say very little, do you mean none, or there is some questionable evidence?

I'm genuinely curious

Re: Webb Discovers Methane, Carbon Dioxide in Atmosphere of K2-18B

#60

Post by no_wizard »

lofaszvanitt wrote: post #30

120 light years away. Time to get the ufo tech out already.

is Faster Than Light travel even possible? I'm asking in a serious way.

I have always read that its impossible, at least within our current knowledge.

the only semi-plausible theory I've ever heard is that Blackholes might one day yield some way of traveling quickly across the universe but nobody has shown anything substantiated around that or anything else.

Post reply on HN