Alien World

I've probably talked about this briefly in other posts, but I would like to muse about what it would be like to step out on an alien world.

By alien world I mean a planet like the ones that were recently discovered around a red dwarf star Trappist-1.

Actually, Trappist-1 is a ultra-cool dwarf star that's just slightly larger than Jupiter. This star is a spectral class M8 V or 2V with a mass of only 0.08 times our Sun and with a diameter only 0.112 of our Sun. The luminosity is very low, only 0.08% of our Sun. The temperature is only 2550 K. Our Sun has a temperature of 5772 K.

What does this mean? It means that you could look up at the star without being blinded. It would appear as large red globe. But, that's not the major impact. Because of the fact that this dwarf star is not throwing out very much heat and light, planets that are in its habitable zone would have to orbit in close. In other words, they have snuggle up close. This would suggest that all planets in the habitable zone would be tidally locked to the star. That means that one side of the planet is always facing the star and the other side is facing away.

If you were on the dayside, the star would be overhead and never set. This side of the planet would be a hot desert devoid of water. If you were on the night side, you would be very cold and likely frozen. Any water would be in the form of ice. On this side you never see the star. It's perpetual night.

The only truly habitable zones on such a planet would be in the twilight zone or terminator, a narrow band circling the planet that has indirect light and dark. Here, surface liquid water is possible, and it would be a crucible for the formation of life.

It's hard to imagine what this would be like. You would see light like at dusk or dawn, but it would very red. Any life that forms here would have large eyes to take in the dim light. Plants would be very dark, possibly black in color to absorb the dim light that mostly in the red and infrared part of the spectrum.

However, there is another problem. Since the two sides of the planet are in extreme temperature zones, winds would flow from the hot side to the cold side at high velocities. Any life that develops in the twilight zone would have to deal with that problem. I'm not sure how that would be. They would have to be ground huggers.

What's strange about this system is that it has seven Earth-size planets in the habitable zone. Four of them are slightly larger than Earth and two are smaller. These planets orbit the star in days not months or years. That's wild!

Another problem is that the atmospheres of the closest planets are being bombarded with heavy X-ray and UV radiation from the star, which would alter the atmospheres of these planets.

The only thing that one could say about these alien worlds is that they are truly alien. They are not like Earth. However, if there is water on them, life could have developed. However the age of the star is greater than a billion years. How much greater is unknown. It is past its youthful period and would be stable. A star like this could burn for 12 billion years. Since it's relatively new on the block, life may not have developed on its planets yet. Only time will tell.

Thanks for reading.