Can humans live under a red sun?

Tom Kalbfus · 2015-11-15 11:49:52

There are a lot of red dwarfs out there, seems likely if we colonize the stars, then there will be a lot of planets orbiting red dwarfs that might otherwise be Earthlike. These planets would likely share some characteristics of Jupiter's moons. In other words the planets orbiting a red dwarf star within its habitable zone will likely be tidally locked with that star, and other nearby planets will be seen from that planet not as points of light but as full disks in the sky. And of course terraforming would be an issue because such planets would likely have to be modified for human habitation. One problem is that only half of each planet would receive sunlight, the other half would be in darkness until we set up reflectors to fix this, and here is the other problem. A planet within the habitable zone orbiting a red dwarf star, would likely have a huge ice cap on its far side. If we set up mirrors to reflect light onto the far side, guess what going to happen to that ice cap?

On the plus side with a tidally locked planet, we can set up any day length we like with orbiting reflectors. We are not stuck with the rotation rate of the planet. a slow rotation without tidal lock, such as what Mercury and Venus have is worse than a tidal lock, as we can either have orbiting mirrors in polar orbit or a counter-rotating mirror outside of the planet's orbit around the star.

The second issue is would people like a bloated red sun in their sky, how would plants like that?

Last edited by Tom Kalbfus (2015-11-15 11:52:44)

Void · 2015-11-15 12:27:07

Factors that matter a lot are the amount of atmosphere, and the amount of water. I used to speculate on those planets a lot.

There is a lot of materials out there to query for if you are interested. Last article I read about it indicated that perhaps 2/3 of the planets could have stable atmospheres. Don't remember why the 1/3 would not.

As for Photosynthesis, that is also covered rather well I think.

For your entertainment, I will take a box of such junk out of my closet for you and leave it on your doorstep to do as you wish.

1) Water worlds. If no ice, then too bad, don't think it's a good bet.
If completely frozen, for photosynthesis, I speculate on the most warm sun overhead point, perhaps some salts in the ice allowing pockets of water in the ice allowing photosynthesis through the ice down to what perhaps -13 Degrees C?
http://www.nature.com/news/life-abounds … ce-1.11884
While such a frozen world might sound harsh, if it is tidal locked, all you need is static heliostats, and a house/greenhouse to make yourself a pleasant situation.

For minerals you will have to get meteors, or drill down to brines, or mine asteroids, moons.

For a water world with an open water circle under the noon sky, I have speculated on plants that would grow on the shore. They would have to be symbiotic with insects, birds (Pseudo Insects, Birds), so that those creatures would bring fertilizer to them. (Excrement, their dead bodies, etc.) They might grow stilts instead of roots. It is possible such plants might eat insects like bog plants on Earth.

Periodic winds might change the weather.
https://en.wikipedia.org/wiki/Katabatic_wind

So as in Antarctica, a pool of cold air accumulates, and then drains in a violent way to the ocean. Therefore the plants animals and insects would have to have methods to cope. "Birds" of course could have evolved from flying fish, and might employ antifreeze, warm bloodedness, and amphibious methods to cope with a freeze. Insects might just have a short life cycle, and hatch out of the water breed, and then die in the next freeze. Plants might need to have methods to make their "Stilts" anchor in the ice, to hold fast against the wind.

However, below such forests, there might be bog, over the ice, so that puts another twist on things, and offers more options.

In my simple models, water currents would tend to cause ice islands to push against the shore and connect to it. Wind storms might blow ice islands out into the sea.

The sea sounds quite cold, but away from the shore, near it's center, perhaps it could be considerably warmer.

Then there might be floating plants as in the Sargasso sea. Maybe even floating trees?

Fun for the imagination.

2) Big island worlds. If the Earth were flooded with more water, and only Tibet and a few things were sticking up. I suspect that the greatest continental mass might point at the star. So, you might have Tibet, a sub-tropical island surrounded by a deep ocean, the waters near the island perhaps even being temperate, particularly if you have some connected inland seas.

Further out cold sea, and then ice pack, which a stilt tree ecology, where sunlight comes in low on the horizon. Then of course on the dark side solid ice pack.

3) Half and Half worlds. Ice covered ocean on the dark side, dry desert on the front side. These sound dead, but depending on how high the ice is piled, or the total mass of ice, there are loopholes I believe.

For instance if the ice is piled high enough, then glaciation will bring replacement ice to the terminator where if might melt or at least evaporate in the sunlight warmed air.

Then there are the Katabatic winds. If they descend quickly they can warm the air on the dark side, and then evaporate ice even in the total darkness perhaps. Water vapor can then turn to snow. Whiteouts could drag large amounts of snow into the sunny side, where it could melt after the wind storm, or evaporate. This can happen in Mongolia I believe where snow gets dragged from Siberia. It definitely happens in Antarctica, but instead of dumping snow on a dry desert where it could melt later and water things, the snow dumps into the sea.

This amount of water vapor in the atmosphere might migrate to the noon point and be sucked upwards (In a very simple wind model).

With altitude might come snow/rain on the noon point, particularly if a Tibet is there.

4) Dark Sea worlds. I am particularly fond of this one, but I think it will be rare.

Mark my word I don't want you putting heliostats on my Dark Sea World!!! (Put them on your own if you like)

Suppose a warm world, warm enough the even a small sea on the dark side would be of temperate temperatures. If you want to get fancy, perhaps you can imagine one bay that actually crosses the terminator into the sunlight. This is all imaginary anyway.

I do worry that such worlds might suffer from run away green house effects, but maybe not if the moisture is kept on the dark side, and very little gets to the sunny side.

So, on the dark sea, I have a cabin. I have windmills around my cabin. When the wind blows lights on the windmill tower light up. My gardens grow, trees grow on the shoreline. I can see other houses on other parts of the shores. The light up and dim in accordance with the amount of wind they are experiencing, and of course you could have a light switch and just turn the lights off if you want.

The winds might be periodic, like weather. For a time the winds would be relatively still, and perhaps things would cool down, the cold of the dark starry sky, penetrating to the surface. On the sunny side a pool of hot air accumulating.

Then a wind storm, similar to Katabatic winds, where the thermal differential is discharged. This warm up things since hot air from the sunny side will slide over the cold air accumulated over the sea. The winds blow, the waves pound, and the lights light up intensely (If you want them to).

In the water on the shore life grows that uses motion for energy. Kenetosynthesis
I came up with that some time ago, but of course so could other people.

http://s1.zetaboards.com/Conceptual_Evo … 4287365/1/

Some micro-organisms use electric motors, so why not plants with electric generators?

This might even happen for land plants as well on the dark side, since they would not be crowded out by photosynthesis or chemosynthesis life forms (Except near my windmills on the shoreline).

5) Artificially induced Dark Sea Worlds. This would be worlds that are dry except for some ice on the dark side. You ask Tom to put orbiting heliostats around them and you melt a sea, creating an artificial Dark Sea World.

Although a dark sea world would seem to waste the day side, it can be noted that you would be able to mine the day side, put Solar and wind generation machines on the day side, and if you wanted to be there (If it wasn't too hot) you could pipe water to the day side from the dark sea.

Why the dark side? Because it's there, and also because it might protect you from severe solar flares.

I hoped this entertained you. Well I got to go now, I am either going to take a walk in the sunlight in the real world or go sailing on the dark sea. Maybe both.

When I look up in the sky, I might see a nearby planet as a disk like Moonlight. Out there in my sailing ship on the dark sea, under the starry sky and a few wispy clouds.

Oh by the way the dark sea could have lots of geothermal energy/life due to tidal heating induced in part from that planet in the sky.

Last edited by Void (2015-11-15 22:16:25)

Void · 2015-11-15 22:18:00

Tom, I hope I did not steal your thunder on this one. I love to go to those worlds in my mind, but hadn't for some time, so you started me up.

Tom Kalbfus · 2015-11-17 10:14:11

Naw. I think most planets are the wrong distance from the sun and have the wrong rotation rates. We got lucky with Mars, but most planets don't have a 24 hour rotation rate, the only thing we can count on is planets orbiting close to red dwarfs will be tidally locked, we can do something about that, on the day side, we can grow plants that remove carbon-dioxide from the air and release oxygen, but perhaps we don't want to live their. It is the night side of these planets that are best for human habitation, and half of an Earth-sized world is still quite a bit, depending on how the continents are arranged of course. Most of the oxygen on Earth is produced by blue-green algae in Earth's oceans, I think those simply plants might not mind a red sun constantly shinning down on them and never setting. On the night side, we can adjust the artificial day length to our preference using giant space mirrors to reflect light on the dark side of the planet, it might take some time to melt all the ice, and of course there will be flooding issues on both hemispheres of the planet when we do this!

Void · 2015-11-17 14:37:42

We are rather close. However per my information;
-Flares will be a danger on the day side. Especially for younger stellar systems.
-Every situation is likely to be different. It is as if in forming a solar system, you have a cake mix. The original mixes are not alike, the results are not the same. Interestingly one article said that solar systems that do not form a Jupiter, might have the mass to make 100?
terrestrial planets? If so, how does that work out?
-Worlds with atmospheres around red dwarf stars, may have very dangerous strong winds. Granted, if you choose to try to live on the dark side, having wind power is great, but if the wind is blowing 500-1000 mph, perhaps that is a challenge.
-I am not sure I quite believe the Blue-Green algae makes the Oxygen thing. I now think that most terrestrial planets are born with an excess of Hydrogen, and until that gets blown away by the solar wind, an Oxygen build up in the atmosphere is limited. Further, planets do not apparently require life to create Oxygen in their atmospheres. The splitting of water by U.V. where Oxygen is retained by the planet, and Hydrogen is lost to the solar wind also works.

Red Dwarfs are also called "Flare Stars". Their flares include intense radiation including U.V., so I am thinking there is rather a potential for terrestrial planets around "Flare Stars" to develop Oxygen in their atmospheres, even if they are dead to life. All that is required is evaporation to expose moisture to U.V. and a gravitational and Magnetic field that favors the retention of Oxygen, and the loss of Hydrogen.

Yup, I think the night time sides are preferred, if they are warm enough.

Last edited by Void (2015-11-17 14:46:06)

Void · 2015-11-17 15:51:09

I once camped on a Northern lake, the https://en.wikipedia.org/wiki/Aurora was fantastic that year.

Can you imagine what the night side of a terrestrial planet with a magnetic field would be like during a red dwarf flare event?

Last edited by Void (2015-11-17 15:51:58)

Terraformer · 2015-11-18 11:19:36

However, a build up of oxygen will cause a build up of ozone, reducing the UV flux at the surface, so it might be self limiting. Also, the surface may become hyper-oxidised?

Void · 2015-11-18 16:05:37

Sounds reasonable to me Terraformer.

In relation to the history of Mars, perhaps a hydrocarbon childhood atmosphere, then moving to an Oxidizing atmosphere (Which might also promote acid PH?), the finally a CO2 dominated atmosphere where, Oxygen from CO2 lost to space is replaced by Oxygen from H20, as water evaporates into the atmosphere.

More CO apparently promotes more Ozone, and Ozone is some type of a greenhouse gas.

More water into the atmosphere, more O2 to the atmosphere when Hydrogen leaves it behind by being swept away by the solar wind. More O2, less CO, less CO less Ozone, less heat, less evaporation.

Simplified, but possibly why the pressure is hanging around 5-7 mb.

Just guessing.

Last edited by Void (2015-11-18 16:06:40)

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#1 2015-11-15 11:49:52

Can humans live under a red sun?

#2 2015-11-15 12:27:07

Re: Can humans live under a red sun?

#3 2015-11-15 22:18:00

Re: Can humans live under a red sun?

#4 2015-11-17 10:14:11

Re: Can humans live under a red sun?

#5 2015-11-17 14:37:42

Re: Can humans live under a red sun?

#6 2015-11-17 15:51:09

Re: Can humans live under a red sun?

#7 2015-11-18 11:19:36

Re: Can humans live under a red sun?

#8 2015-11-18 16:05:37

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