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Space NASA

NASA Has Discovered an Earth-Sized World in a Star's Habitable Zone (youtube.com) 59

Posted by EditorDavid from the exploring-strange-new-worlds dept.
"NASA's Transiting Exoplanet Survey Satellite (TESS) has discovered its first Earth-size planet in its star's habitable zone, the range of distances where conditions may be just right to allow the presence of liquid water on the surface," reports NASA's Goddard Space Flight Center: Scientists confirmed the find, called TOI 700 d, using NASA's Spitzer Space Telescope and have modeled the planet's potential environments to help inform future observations.

TOI 700 is a small, cool M dwarf star located just over 100 light-years away in the southern constellation Dorado. It's roughly 40 of the Sun's mass and size and about half its surface temperature. The star appears in 11 of the 13 sectors TESS observed during the mission's first year, and scientists caught multiple transits by its three planets. The innermost planet, called TOI 700 b, is almost exactly Earth-size, is probably rocky and completes an orbit every 10 days. The middle planet, TOI 700 c, is 2.6 times larger than Earth -- between the sizes of Earth and Neptune -- orbits every 16 days and is likely a gas-dominated world. TOI 700 d, the outermost known planet in the system and the only one in the habitable zone, measures 20 larger than Earth, orbits every 37 days and receives from its star 86% of the energy that the Sun provides to Earth.

All of the planets are thought to be tidally locked to their star, which means they rotate once per orbit so that one side is constantly bathed in daylight... While the exact conditions on TOI 700 d are unknown, scientists used current information, like the planet's size and the type of star it orbits, and modeled 20 potential environments for TOI 700 d to gauge if any version would result in surface temperatures and pressures suitable for habitability.

One simulation included an ocean-covered TOI 700 d with a dense, carbon-dioxide-dominated atmosphere similar to what scientists suspect surrounded Mars when it was young. The model atmosphere contains a deep layer of clouds on the star-facing side. Another model depicts TOI 700 d as a cloudless, all-land version of modern Earth, where winds flow away from the night side of the planet and converge on the point directly facing the star.
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NASA Has Discovered an Earth-Sized World in a Star's Habitable Zone More

NASA Has Discovered an Earth-Sized World in a Star's Habitable Zone

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  • Title: NASA Has Discovered an Earth-Sized World in (Score:5, Informative)

    by pepsikid ( 2226416 ) on Saturday January 11, 2020 @09:56PM (#59611032)

    Article: TOI 700 d, the outermost known planet in the system and the only one in the habitable zone, measures 20 larger than Earth

    • Comment removed based on user account deletion

      • Re: (Score:2)

        by jmccue ( 834797 )

        It's roughly 40 of the Sun's mass

        I think he is making fun of the summary. I believe I read something about this a few days ago, I think it is a red dwarf star and the planet in question is tidally locked it's "sun".

        I was bad in English class (native speaker), but I really hope the person who wrote the summary is not a native speaker of English, otherwise all it proves for sure is how poor our education system is.

        • I believe I read something about this a few days ago, I think it is a red dwarf star

          Red dwarf star? Which one? Kryten? Rimmer? Holly? Cat? Smeghead Lister?

      • Yeah, the summary makes no sense. The summary says:

        TOI 700 d, the outermost known planet in the system and the only one in the habitable zone, measures 20 larger than Earth

        The abstract of the paper says:

        TOI-700 d, a habitable zone Earth-sized planet in a multiplanet system

        https://arxiv.org/abs/2001.009... [arxiv.org]

        • The system can very well have multiple planets, but have only a single planet within the habitable zone. The zone does not exist as the entire radial distance from the host sun, but as a ring. For example, Mercury would not be in our habitable zone. It is far too hot to sustain life. A solar system could theoretically have 5 planets around a sun as relatively close and hot as Mercury, and then a single planet much farther away within the habitable zone. This description also leaves open the possibility

      • It measures 20 times. As in "Measure 20 times, cut once."

        • Shit, that means it has some sort of unattended satellite defense system left over from a past civilization.

          I hope they locked out the gate address, because that episode has been done too many times already.

      • Re:Title: NASA Has Discovered an Earth-Sized World (Score:5, Informative)

        by darthsilun ( 3993753 ) on Saturday January 11, 2020 @10:34PM (#59611102)
        Well, if you bothered to try other sources, the wikipedia[1] article about TOI 700d says its radius is 1.19 that of Earth and its mass is 1.79 that of Earth.

        But I guess it's more fun to whine about crappy a crappy youtube writeup.

        [1] https://en.wikipedia.org/wiki/... [wikipedia.org]
        • And [2] says "... it's just 20% larger than Earth."

          https://www.space.com/nasa-tes... [space.com]

          • Yes, so the /. summary is missing percentage.

            From the summary

            TOI 700 d, the outermost known planet in the system and the only one in the habitable zone, measures 20 larger than Earth

            Makes no sense at all

          • its radius is 1.19 that of Earth and its mass is 1.79 that of Earth

            "it's just 20% larger than Earth."

            No, Cartman, the planet is not big boned. It's just not actually very Earth-like.

        • I think he/she was pointing out is that the title of the Slashdot article contradicts what the summary says, rather than anything in the youtube video

          • Without knowing what 20 it is larger than Earth, you can't say that the title contradicts the summary. It could be metres, it could be miles, it could be percent, it could be times.

            It's percent, as it happens. 20% larger than Earth, which is close to Earth-sized.

            • That's why I linked to the original paper that says it's 20% (roughly) larger than Earth. It's a reasonable inference that the % symbol (or word) has been omitted. I cannot be metres or miles or volume because the numbers don't add up. The only reasonable inference is percentage of size, as written in the paper

      • 20 speed

      • What is also not very clear is "measures 20 larger than Earth".
        20 what? ...
        Damn it, be clear and precise!

        Exactly 20 baby Cthulhu.

    • Re:Title: NASA Has Discovered an Earth-Sized World (Score:4, Informative)

      by argStyopa ( 232550 ) on Saturday January 11, 2020 @11:40PM (#59611214) Journal

      The video shows they missed the "%"...it's 1.2x the size of earth.

      1) a M class star is quite small...in this case, about 40% the mass of the sun, and quite a bit cooler. As an M2V (https://en.wikipedia.org/wiki/TOI_700) it's about half the temp of our sun.

      2) TOI700d is only orbiting about 0.16 AU out, with a 40 day year. This would suggest that it's tidally locked.

      This is a great find, only about 100ly from earth.

      But understand: the geophysics of a world in the habitable zone that's tidally locked are frankly so far beyond us right now it would be silly to draw conclusions at this point. My bet would be that tidal-locking will largely defeat the 'habitablity' of the zone well further out, if not completely.

      Whatever it is, it's going to be interesting.

  • That is pretty close. I figure it would only take 1,900,000 years to get there with a manned spacecraft.

  • Its tidally locked to the star, so even though it would receive a similar amount of heat, one side of the planet is too hot, and the side facing away from the star is too cold.

    And at 100 ly away, its not worth even sending a probe to , until we invent some FTL drive.

    • Re:Not habitable (Score:4, Interesting)

      by KiloByte ( 825081 ) on Sunday January 12, 2020 @12:49AM (#59611370)

      A temperature gradient from too hot to too cold means there's an area that's just right. Even better, the heat gradient allows trivial generation of massive amounts of energy.

      Also, too hot/cold places are not a concern if you forsake going outdoors. Digging in offers a cheap low-tech way to provide isolation, sci-fi domes are a high-tech way that gets you the view of the sky, and those who insist on "the real thing" have the terminator belt to live in.

      • A temperature gradient from too hot to too cold means there's an area that's just right.

        There is no reason for this to be true. More likely, you'd have a very stormy and windy zone where local conditions vacillate between too hot and too cold.

        Stable, moderate temperatures would be more likely to be found in deep valleys on the hot side, or geothermal zones on the cold side.

  • Am I correct that on a tidally locked planet atmosphere and water will be frozen solid on the dark (cold) side of the planet, leaving the "sunny side" water- and airless? The whole planet should work as a cryopump.

    • No.

      You could have a dark side and a bright side with no temperature difference, because it is completely eroded by atmospheric circulation. Or anything in between. And that is not even counting the heat that is due to radioactive decays in the planet itself.

      Venus would be an example of the influence of the atmosphere, it turns around very slowly, its day is a bit longer than half its year, so you'd think there are similar large differences, yet the temperature all over its surface is basically the same

      • > You could have a dark side and a bright side with no temperature difference,

        That does not seem possible. Even at Earth's orbit, the sunlight provides roughly 2 watts/square centimeter of power: that _will_ warm the sunward side, and the nightside will radiate to space and stay cooler. How much it cools the backside is a fascinating thermodynamics and chemistry question.

        • Re: (Score:2)

          by ceoyoyo ( 59147 )

          He gave you an actual example: Venus.

          • Yes, and Venus has a battery acid atmosphere. That may have a little something to do with it.

            • Re: (Score:2)

              by ceoyoyo ( 59147 )

              You might want to actually read the thread before replying.

            • Venus has a carbon dioxide atmosphere. The "battery acid", by which I guess you mean the sulfur dioxide, is a trace gas, that is, there is very little of it, on the order of a hundred particles per million. Neither has much to do with the uniform temperature, atmospheric circulation and albedo do.

          • It's not a good example. It's not tidally locked. Coupled with the very thick atmosphere, there is very strong weather and no opportunity for the dark side to cool down enough for the atmosphere to freeze.

            • Re: (Score:2)

              by ceoyoyo ( 59147 )

              The solar day on Venus is over three months long, yet its temperature is very uniform. If you want to quibble about the difference between complete tidal locking and a three month day, you'll either have to believe simulations or wait until someone figures out how to reliably measure both sides of a suitable extrasolar planet. Or I guess post "that does not seem possible" on Slashdot. Whatever does it for you.

            • Venus is actually a very good example of the phenomenon.

              It has a very long day exactly because it is nearly tidally locked and rotates very slowly, which gives any given piece of its surface a very long time to be exposed to heat or cold, and an "opportunity" to change its temperature - up, or down. There would be a large temperature differential but the rotation of the atmosphere, which actually turns faster than the planet itself cancels it.

              Now, you could have asked why is the atmosphere of Venus rotat

            • As you say, it's not tidally locked, so there is - in the meaning of this conversation - no dark side.

  • TOI 700 is a small, cool M dwarf star located just over 100 light-years away in the southern constellation Dorado. It's roughly 40 of the Sun's mass...

    I think they mean 40%, not 40x.

  • What the hell are we waiting for, get a space probe over there ASAP! It's only 100 light years away, how long could it take to get there? Elon could send a colony shop there.

  • Adapt or die, we learned from school. So we should practice these soon-to-be common expressions:
    But boss, that will take another week--er, ten more days"
    "I'll give you seven"
    "A week?"
    "...days"
    "D'oh!"

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