Jul 9, 2020 06:25 PM
(This post was last modified: Jul 9, 2020 06:26 PM by C C.)
Planet 9': Harvard scientists launch plan to find 'primordial black hole' at edge of solar system
https://www.independent.co.uk/life-style...11006.html
Tidally-locked worlds could harbor conditions for life after all
https://www.knowablemagazine.org/article...pport-life
EXCERPTS: . . . When gravitational forces slow or accelerate the rotation of an astronomical body it can become tidally locked to its parent body (in this example, a planet is tidally locked to its star). Under these conditions the orbiting body always shows the same face to its parent body. Our moon is tidally locked to Earth and scientists suspect that many exoplanets orbiting relatively close to their stars may also be tidally locked.
Many of these planets will be inhospitable, baked on one side and frozen on the other. Yet astronomers have long contemplated whether such worlds might harbor life, as have sci-fi enthusiasts. Now sophisticated computer modeling and new data are illuminating more about the atmospheres of these tidally locked, distant worlds. The research is adding weight to the notion that some may not be so hostile.
“There’s nothing really especially bad about tidal locking,” says physicist Raymond Pierrehumbert of the University of Oxford in England. “The day side is perfectly good habitat and there’s quite a lot of it.”
[...] Optimism regarding the habitability of the “twilight zone” also emerged in the world of science fiction, says University of Chicago geophysicist Dorian Abbot. The idea was that the region between the planet’s light and dark side would be mild enough for water to exist in liquid form and perhaps allow life to survive. Research has cast doubt on that theory.
The twilight zone — which astronomers call the “terminator” — would be a poor place for organisms that need the sun’s light to survive. Twilight, the gradual transition from day to night [...] has captured people’s imagination as a place that might support life on exoplanets. But a twilight zone, or the terminator in astronomy parlance, may not be the only habitable portion of an exoplanet if it has a suitable atmosphere. [...] you don’t need a twilight zone to support life if you have the right atmosphere, says Abbot.
An atmosphere transports heat around the planet, making conditions that could support liquid water — and perhaps life — more widespread. “It wouldn't just be at the terminator,” geophysicist Dorian Abbot says, “it would be all over the place.”
There’s a balancing act: The atmosphere needs to be dense enough to transport heat, but not so dense as to become smothering. Conversely, if the nightside becomes too cold, it could freeze the gases out, stealing an atmosphere entirely. A 2016 simulation developed by Abbot and Koll indicates that the right balance is achievable: Some tidally locked exoplanets could host “just right” atmospheres that move heat around efficiently enough to keep even the night side warm.
“It would be strange because it would be permanently night but you might still have conditions where life similar to ours could exist,” says planetary scientist Daniel Koll. Consider the poles on Earth, where life persists, even though sunlight is scarce. “It doesn’t get too deadly cold, in great part because wind or motions of the ocean actually redistribute heat.” (MORE - details)
https://www.independent.co.uk/life-style...11006.html
Tidally-locked worlds could harbor conditions for life after all
https://www.knowablemagazine.org/article...pport-life
EXCERPTS: . . . When gravitational forces slow or accelerate the rotation of an astronomical body it can become tidally locked to its parent body (in this example, a planet is tidally locked to its star). Under these conditions the orbiting body always shows the same face to its parent body. Our moon is tidally locked to Earth and scientists suspect that many exoplanets orbiting relatively close to their stars may also be tidally locked.
Many of these planets will be inhospitable, baked on one side and frozen on the other. Yet astronomers have long contemplated whether such worlds might harbor life, as have sci-fi enthusiasts. Now sophisticated computer modeling and new data are illuminating more about the atmospheres of these tidally locked, distant worlds. The research is adding weight to the notion that some may not be so hostile.
“There’s nothing really especially bad about tidal locking,” says physicist Raymond Pierrehumbert of the University of Oxford in England. “The day side is perfectly good habitat and there’s quite a lot of it.”
[...] Optimism regarding the habitability of the “twilight zone” also emerged in the world of science fiction, says University of Chicago geophysicist Dorian Abbot. The idea was that the region between the planet’s light and dark side would be mild enough for water to exist in liquid form and perhaps allow life to survive. Research has cast doubt on that theory.
The twilight zone — which astronomers call the “terminator” — would be a poor place for organisms that need the sun’s light to survive. Twilight, the gradual transition from day to night [...] has captured people’s imagination as a place that might support life on exoplanets. But a twilight zone, or the terminator in astronomy parlance, may not be the only habitable portion of an exoplanet if it has a suitable atmosphere. [...] you don’t need a twilight zone to support life if you have the right atmosphere, says Abbot.
An atmosphere transports heat around the planet, making conditions that could support liquid water — and perhaps life — more widespread. “It wouldn't just be at the terminator,” geophysicist Dorian Abbot says, “it would be all over the place.”
There’s a balancing act: The atmosphere needs to be dense enough to transport heat, but not so dense as to become smothering. Conversely, if the nightside becomes too cold, it could freeze the gases out, stealing an atmosphere entirely. A 2016 simulation developed by Abbot and Koll indicates that the right balance is achievable: Some tidally locked exoplanets could host “just right” atmospheres that move heat around efficiently enough to keep even the night side warm.
“It would be strange because it would be permanently night but you might still have conditions where life similar to ours could exist,” says planetary scientist Daniel Koll. Consider the poles on Earth, where life persists, even though sunlight is scarce. “It doesn’t get too deadly cold, in great part because wind or motions of the ocean actually redistribute heat.” (MORE - details)