alfa015 Posted September 14, 2019 Posted September 14, 2019 As of September 2019, these are the 5 potentially habitable exoplanets closer to Earth: SPAM DELETED 1.GLIESE 273 b Gliese 283 b orbits the red dwarf star Luyten, located 12 light years away. - The exoplanet is 84% similar to Earth. - It has an orbital period of 18.6 days. - A minimum mass 2 times higher than Earth. - An average radius 40% higher. - And an equilibrium temperature of 11 degrees more. 2. TEEGARDEN b Teegarden b orbits the red dwarf star Teegarden, 12 light years away. - The exoplanet is 95% similar to Earth. - It has an orbital period of 5 days. - A minimum mass and average radius only 5% higher than Earth. - And an equilibrium temperature of 9 degrees more. 3. GLIESE 1061 c Gliese 1061 c orbits the red dwarf star Gliese 1061, 12 light years away. - The exoplanet is 88% similar to Earth. - It has an orbital period of 6.7 days. - A minimum mass 75% higher than Earth. - And an equilibrium temperature of 20 degrees more. 4. TAU CETI e Tau Ceti e orbits the solar-type star Tau Ceti, 12 light years away. - The exoplanet is 74% similar to Earth. - It has an orbital period of 163 days. - A minimum mass 3 times higher than Earth. - An average radius 60% higher. - And an equilibrium temperature of 30 degrees more. 5. PROXIMA B Finally, Proxima b orbits the red dwarf star Proxima Centauri, 4.2 light years away. - The exoplanet is 87% similar to Earth. - It has an orbital period of 11 days. - A minimum mass 30% higher than Earth. - An average radius 10% higher. - And an equilibrium temperature of 28 degrees less. To which of these exoplanets would you go to? why?
Airbrush Posted September 14, 2019 Posted September 14, 2019 (edited) I'd go to Teagarden b because the gravity would be only 5% higher than Earth. I can't imagine stepping out onto a planet that has even 20% higher gravity than Earth. That would be very uncomfortable. Edited September 14, 2019 by Airbrush
Ken Fabian Posted September 14, 2019 Posted September 14, 2019 "Habitable" in popular usage seems to be a quite flexible term. I suspect most people - who get news of exoplanets from news and current affairs TV - are imagining something people could live on, tapping into that primitive urge of humans to strike out for new lands with untapped resources, away from all that competition. I remain deeply sceptical myself. Borrowing some xkcd insight-
beecee Posted September 14, 2019 Posted September 14, 2019 6 hours ago, alfa015 said: As of September 2019, these are the 5 potentially habitable exoplanets closer to Earth: A more accurate assessment should have been "5 known planets, that may potentially be able to support some basic life, as we know it"
MigL Posted September 14, 2019 Posted September 14, 2019 (edited) There are questions regarding the suitability of red dwarf stars to sustain life ( as Ken's comic points out ). Because the star is so small, orbiting planets are extremely close ( notice those orbital periods ? ), and planets may become tidal locked. IOW they keep the same face to their sun , leading to extreme temperature differentials between the night and day sides. Red dwarfs are also convective ( a constant mixing of the He build-up throughout the star ) leading to excessive flare activity. That, and the large shifting magnetic fields, may make close proximity to the star uninhabitable. I would head to Tau Ceti e. But I'd be extremely uncomfortable weighing almost 600 lbs, and sweltering in 60 deg. C temperatures. ( habitable zone my a*s ) Edited September 14, 2019 by MigL
Sensei Posted September 14, 2019 Posted September 14, 2019 (edited) On 9/14/2019 at 5:24 PM, alfa015 said: - It has an orbital period of 18.6 days. - It has an orbital period of 5 days. - It has an orbital period of 6.7 days. - It has an orbital period of 11 days. This make them uninhabitable from POV of human.. New Year celebration every 5 days? They would be drunk entire year.. On 9/14/2019 at 5:24 PM, alfa015 said: To which of these exoplanets would you go to? why? None of the above.. Edited September 15, 2019 by Strange inhabitable -> uninhabitable
Janus Posted September 15, 2019 Posted September 15, 2019 20 hours ago, Airbrush said: I'd go to Teagarden b because the gravity would be only 5% higher than Earth. I can't imagine stepping out onto a planet that has even 20% higher gravity than Earth. That would be very uncomfortable. If we use the numbers given of a 5% larger radius and a 5% larger mass, then the surface gravity would be 1.05/1.052 = ~0.95g. It would be the escape velocity that would be 5% higher, Though I 'm not sure that this would be enough for the planet to hold on to its atmosphere. Being as close to its parent star as it is would subject it to quite intense solar winds. 16 hours ago, MigL said: I would head to Tau Ceti e. But I'd be extremely uncomfortable weighing almost 600 lbs, and sweltering in 60 deg. C temperatures. ( habitable zone my a*s ) Not to pry, but how much do you weigh?!! 3 times the mass and a 60% greater radius gives a surface gravity of 1g x 3/1.602 = ~1.17g So unless you presently weigh over 500 lbs... It would be a bit tougher to leave however, with an escape velocity almost 1.9 times that of the Earth.
mistermack Posted September 15, 2019 Posted September 15, 2019 The surface gravity would not have much effect on creatures in the seas. I don't really get what they mean by equilibrium temperature. You would need to know what sort of atmosphere the planet had to estimate the actual surface temperatures. Without our greenhouse gases in the atmosphere, we would have about -20 at the surface on average. ( my guess, I couldn't be bothered to look it up ). With most of the oceans capped by ice, the albedo would be increased, and we'd probably end up living in an ice-covered planet.
MigL Posted September 16, 2019 Posted September 16, 2019 My mistake Janus. I read it as 3 Gs instead of 3x the mass. ( I weigh close to 200 lbs )
Airbrush Posted September 16, 2019 Posted September 16, 2019 Let me know when they find an Earth 2.0 that has about 90%G surface gravity. That will be exhilarating to feel 10% less heavy. Every load you carry is 10% lighter. Also I would like a sun-like star and a big moon, and a big guardian Jupiter.
mistermack Posted September 17, 2019 Posted September 17, 2019 I just looked up equilibrium temperature, and it's the theoretical surface temp without any greenhouse atmosphere. So the equilibrium temperature here on Earth is -18 c. The greenhouse effect knocks that up to an average surface temperature of + 15 c. Since water vapour is the major greenhouse gas, and we are presumably looking for a planet with plenty of water, you would be best advised to look for a star with a planet like Earth, with oceans, and an equilibrium temperature of approximately -18 c. I would personally think that planets are not the thing to look for, if you want to colonise other stars. The most useful things to find would be rocky and watery lumps in huge quantities, free floating like Saturn's rings or a protoplanetary disk. You would then have raw materials, easily available, to build space stations to live on. Planets have the major drawback of costing mega-bucks to launch things from. Smaller bodies free-floating could be mined and used with hardly any energy costs. If we had something like that available near the Earth, it would make a big difference to the problem of living in space.
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