Unlocking the Habitable Potential of Tidally Locked Planets

[@Alien_Planetology]

Excellent video! I am surprised that you didn't mention the "cold trap" scenario where the atmosphere does not transport enough heat to the dark side of the planet to raise its temperature above freezing, causing the moisture in the atmosphere to freeze out onto the surface. I've always considered that to be the greatest concern for the habitability of red dwarf planets. (At least for planets resembling Earth in mass and water content.)

[@AstroPhil2000]

Thank you, great question. I was aiming to outline the effect the atmosphere has on these types of planets, can do a more specific one focusing on the cold trap scenario. Things like this really do highlight just how diverse the population of planets is.

[@aisutistoto5771]

According to the most accurate models, an "earth-like" tidaly locked world would NOT have a big-ass uninhabitable desert and uninhabitable frozen side. The substellar point would, in fact, be Tropical with lots of storms! The dark side would just be cold and dark but still have life.

[@AstroPhil2000]

I think it depends really. If there is sufficient transport of heat in the atmosphere it could even out the temperature differences, but if, for example, if it is a fairly dry planet then you end up with very hot and very cold locations. However, if it is Earth-like, it would be "wet" and probably more like you say.

[@mongrelmarcos5488]

Great video mate. I would like to know more on tidally locked planets even if mostly estimations. Specifically to how would tectonic plates work(I red that around 28% of tidally locked planets have tectonic plates). How would magnetic fields and the planet's poles would work? How would the direction of winds form with 2 polarising temperatures which I'd assume would also cause some very powerful storms? How would a large ocean behave assuming the tidally locked planet has no moon?

[@AstroPhil2000]

Thanks and great questions! I never even thought about plate tectonics on tidally locked planets. However, it is something that has been studied and it was determined that similar large scale flows (internal) could drive plate tectonics, but focused on the night and day sides, unlike Earth. A link to the science paper if your interested: iopscience.iop.org/article/10.3847/2041-8213/abe400 Yes, the temperature difference between night and day would cause large winds and storms. But this is determined by the water content which can either help or hinder the transport of energy. If the planet was tidally locked and had an eccentric orbit (like Io), the tidal bulge would be in the same location in the ocean but grow and shrink as it moved closer and further away from the star. But if it was locked and circular, there would be no tides like we experience here on Earth as there would be no change.

[@ramalamadingdong3748]

For the ocean world scenario. If it would get too hot in what we consider the habitable zone, wouldn't that imply that if it was a little further away and receiving less solar energy, but still close enough to be tidally locked, that it could be cool enough to be habitable?

[@AstroPhil2000]

That is what makes these planets interesting as the circulation in their atmospheres has a big effect on their global and local temp. Being the right distance to have the right temp is only part of the equation. But yes it might be that certain types of planets have slightly different habitable zones associated with them.

[@rhoddryice5412]

Thee are a few factors I never hear anyone really consider: Obliquity, inclination and spin/orbital resonance. But are the tidal forces to strong for those to be interesting? Will the obliquity for a planet in a close orbit around an M dwarf always be 0? Here in our own system we can see a lot of evidence for a violent past and extreme tilts. A planet around an M dwarf with an extreme tilt of 90˚ would get a day/night cycle of a few earth days. A spin/orbital resonance like for Mercury or Venus would create a day/night cycle too. But even if a planet in Trappist-1 is at 0 tilt and in a 1:1 tidal lock the other planets will still be tugging and make it wobble slightly there might be brighter and darker times along the “dusk zone”. Do you’ve got any thoughts on this?

[@AstroPhil2000]

With tidally locked planets, things like inclination and obliquity typically dampen, so they are less of an issue. Or even need to be discussed. Although, that is not 100% the case, but most will undergo a tidal realignment, such that the spin-orbital planes align.

[@ЕрланБаймуханов-и1у]

Those tidally locked planets could have moons which are not tidally locked to star. Those moons way more preferable to be colonised.

[@AstroPhil2000]

Those moons would be very interesting to live on. Although, the planets would be very close to their stars when tidally locked. Therefore, they are unlikely to be able host stable orbits for moons due to the strong tides from the stars.

[@matheussandbakk9959]

But wouldn't air from the sunside rise as it heats up for it to travel to the cold side. This would create low pressure and pressure differences which forces the cold air from the nightside to push to the sunside. Obviously this assumes the temperature is thick enough that the air on the nighside doesn't just condense

[@AstroPhil2000]

Yes, that is right it would, and it is this process that can drive high-speed winds that circulate air around to the night side. It also can warm the night side more than it would have been otherwise.

[@matheussandbakk9959]

@@AstroPhil2000 Yes, but it not in return also help cool down the Sunside? Sure the temperature differences would still be extreme, but it would probably help moderate both sides to some extent

[@AstroPhil2000]

@@matheussandbakk9959 Yes it does help spread the heat over the planet, the only downside is the very fast winds. If the planet has a weak or no atmosphere then the two extremes of temperature will remain.