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

nasa.gov

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

#11

Post by tracedddd »

unsupp0rted wrote: post #8
sgt101 wrote: post #2

Gosh - imagine that place! I wonder how old this world is, and how stable its enviroment is/has been. Complex animal life took 3.5 bn years to emerge on Earth, of course that's a meaningless data point by itself but intuitively for this place to have an ecosystem or complex life it needs to be old. Still, even without this what a wonderful and weird environment.

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

Not certain at all, it’s based on last universal common ancestor estimates(LUCA) and supported by (lack of) fossil record.

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

#13

Post by julienchastang »

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.

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

#14

Post by v8xi »

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 more CH bonds before ultimately breaking down into methane again. Hence, an exoplanet with both molecules in its atmosphere is a promising candidate in the search for life.

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

#15

Post by bilekas »

willis936 wrote: post #7
ZunarJ5 wrote: post #6

This feels like a big deal. The website seems to be getting hammered as it is working on and off.

What makes it feel like a big deal? Carbon, oxygen, and hydrogen are extremely abundant. Those molecules are relatively low energy combinations of the elements. I would be surprised to not find them in the atmospheres of big rocky planets.

Apperantly it seems to be the presence of " dimethyl sulfide ". It seemingly only produced, on earth at least, by life. So using us as a baseline it seems pretty interesting.

> DMS is generated by the degradation of dimethylsulfoniopropionate, which is present in many species of marine algae and plants, including dinoflagellates and coccolithophores

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

#16

Post by delta_p_delta_x »

unsupp0rted wrote: post #8
sgt101 wrote: post #2

Gosh - imagine that place! I wonder how old this world is, and how stable its enviroment is/has been. Complex animal life took 3.5 bn years to emerge on Earth, of course that's a meaningless data point by itself but intuitively for this place to have an ecosystem or complex life it needs to be old. Still, even without this what a wonderful and weird environment.

> 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.

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

#17

Post by julienchastang »

On this topic, I just finished reading "A Very Short Introduction to Planetary Systems"[0] by Raymond T. Pierrehumbert. He devotes a good portion of the book to exoplanet atmospheres. It is one of the best science books I've read. Pierrehumbert really has a knack for explaining complex material clearly and concisely. I really recommend it.

[0] https://global.oup.com/academic/product/planetary-systems-a-...

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

#18

Post by julienchastang »

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…

Thanks for the book recommendation. Added to reading list.
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