Existential dread time: One day Earth's oceans will boil. This exoplanet might reveal when
- Reference: 1687419310
- News link: https://www.theregister.co.uk/2023/06/22/lp8909c_webb_experiment/
- Source link:
Discovered in 2022, [1]LP 890-9c orbits a red dwarf star, located about 100 light years away, and is 37 per cent bigger than Earth. Red dwarves are cooler than our own G-class sun, so LP 890-9c orbits at just four million miles (6.4 million kilometers) from its Sun. Yet boffins think it might host liquid water.
If it does, that would place the planet in the habitable zone – a region that is sufficiently distant from a Sun to allow life to emerge, but not so hot that life can't survive or oceans boil away.
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The latter fate befell Earth's hellish neighbor Venus, which lies outside the habitable zone of our solar system.
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"[LP 890-9c] is fascinating because it is just at the edge of the habitable zone, at the inner edge, so closer to the Sun than the Earth, but not as close as Venus," Lisa Kaltenegger, assistant professor of astronomy at [5]Cornell University , told The Register .
Kaltenegger is part of a team of researchers trying to figure out the limits of the habitable zone around a star. "It is exactly where a planet should still be a hot Earth but could have started on its path to water-loss and Venus-like conditions already. How hot does a planet have to get to bleed all its life-giving water to space? We don't know for sure, so this planet could help us solve that mystery," she added.
[6]Alien life on Super-Earth can survive longer than us due to long-lasting protection from cosmic rays
[7]Astronomers spot Earth-sized exoplanet probably 'carpeted' by volcanoes
[8]James Webb Space Telescope finds first evidence of CO 2 in exoplanet atmosphere
[9]We've seen things you people wouldn't believe. A planet, dense as a marshmallow, that would float on water
In a paper [10]published in the Monthly Notices of the Royal Astronomical Society , the team developed different models for the planet's climate. Options include a wet and mild world like Earth, a steamy greenhouse world with a runaway greenhouse effect, or hot and barren like Venus.
The models outline the different spectra that scopes like the Webb could observe by examining starlight filtered through the exoplanet's atmosphere. "Our research shows that the planet would look very different to a telescope if it was still a hot but habitable Earth, or if it is bleeding all its water to space, or if it is already a desolate, inhospitable Venus," Kaltenegger explained.
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The researchers plan to submit a proposal to observe LP 890-9c using the JWST. Studying the object would not only help confirm whether liquid water might exist on an exoplanet and if it might be habitable, but could also reveal what conditions might be like on Earth one day as the Sun ages and expands.
"The Sun, like every star, gets more luminous with time, so in about a half [a billion] to one billion years, it should get so hot on Earth that our oceans start to evaporate if we don't manage to reduce the sunlight hitting the Earth. But how hot is too hot? We think the energy from the star that hits LP 890-9c will make it hot, but not inhospitable yet," she hypothesized.
"If it is a habitable world, Earth might have more time than we thought before our oceans evaporate. If it is already an inhospitable world without water, then we might have less time than we thought. That is how the planet gives us a glimpse into Earth's far future." ®
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[1] https://exoplanets.nasa.gov/exoplanet-catalog/8569/lp-890-9-c/
[2] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2ZJQbwIo5-qOqWS2IkcU7ZgAAABQ&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0
[3] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44ZJQbwIo5-qOqWS2IkcU7ZgAAABQ&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[4] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33ZJQbwIo5-qOqWS2IkcU7ZgAAABQ&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[5] https://news.cornell.edu/stories/2023/06/exoplanet-may-reveal-secrets-about-edge-habitability
[6] https://www.theregister.com/2022/01/15/alien_life_superearth/
[7] https://www.theregister.com/2023/05/18/astronomers_spot_new_earthsized_exoplanet/
[8] https://www.theregister.com/2022/08/26/jwst_co2_exoplanet/
[9] https://www.theregister.com/2022/10/21/exoplanet_toi3757_b/
[10] https://academic.oup.com/mnrasl/article/524/1/L10/7198488
[11] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44ZJQbwIo5-qOqWS2IkcU7ZgAAABQ&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[12] https://whitepapers.theregister.com/
Well, Humanity could plausibly have built a swarm of space umbrellas to control the amount of radiation that reaches Earth, and could plausibly have built an asteroid deflection facility on the Moon by then, so if we can avoid scorching the Earth ourselves in the meantime, we might have a fighting chance to still be on Earth.
Not to mention that, in half a billion years, there's plenty of time for scores of generation ships to carry excess population to viable destinations while they slowly go crazy and forget why they're in space in the first place . . .
> Humanity could plausibly
I disagree on "plausibly". There is no profit in saving somebody else's great-great-children, so nothing will be done, intensively.
Also, the biggest danger for humanity probably isn't what might be coming from space, but humanity itself: Wars, the slow deterioration of the planet we're depending on, the general " Après moi le déluge " attitude, I'm afraid we don't really need any help to go extinct...
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> while they slowly go crazy
Even crazier?... Seriously, I rather think they will continue to live their lives, just like on Earth, absorbed by the current fads and their own personal needs and aspirations. The environment is just the pretty unimportant setting for the big picture that is their life. As about forgetting, they will do that about a week after having settled in the ship and having started to live "normally".
I'm more concerned about the "viable destinations" part, because unlike what we see in the 50-60ies SciFi movies, distant planets don't come fully equipped with readily available drinking water, breathable atmosphere and fertile soils. Of course you could "terraform", but what most people like to forget is that it takes a lot of time* (and about as much money!), and here again nobody will want to spend their hard-earned money so somebody else's great-great-children can live a nice life on another planet.
* [1]Wikipedia says it took about half a billion years to create Earth's oxygen. Which means we should start sending huge space cargoes full of cyanobacteria to whatever suitable planet we plan on colonizing NOW, we have just the time!...
[1] https://en.wikipedia.org/wiki/Great_Oxidation_Event
"Red dwarves are cooler than our own G-class sun, so LP 890-9c orbits at just four million miles (6.4 million kilometers) from its Sun."
I'm having trouble with that sentence. It seems to be saying that the cooler the star, the closer its planets orbit. Tell me it ain't so?
It also suggests that the planet may have had a choice in how far out it was orbiting!
What it actually meant is the cooler the star, the closer the inhabitable zone is to the star.
> It seems to be saying that the cooler the star, the closer its planets orbit.
Just survivor bias. As UCAP already said above, it's just the habitable zone which is closer, so eligible planets are necessarily closer. It doesn't mean there aren't other planets further way, it's just that they would be frozen and unlikely to harbor life.
The distance of the "habitable zone" (narrow zone where liquid water can exist) depends on how much heat the star emits.
By that time, we either have long since settled other planets, or we're long since extinct. I can't see any plausible scenario where humanity is still present on Earth, but not anywhere else, in half a billion years.