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  • [♩INTRO]

  • In the last twenty-five years or so,

  • astronomers have discovered thousands of planets orbiting other stars.

  • And at this point, they have a pretty good idea

  • what these planetary neighborhoods are like.

  • For example, they know we don't typically see planets similar to Neptune

  • very close to their stars, probably because worlds like that

  • would lose their atmospheres to the star's radiation.

  • But, of course, there are some exceptions.

  • At the end of April, researchers announced that they found a Neptune-like planet

  • in the scorching region immediately surrounding its star.

  • Get out of there little planet!

  • Go!

  • Their news was published in the Monthly Notices of the Royal Astronomical Society,

  • and figuring out how this object ended up there could help scientists

  • understand how solar systems evolve.

  • The world is called NGTS-4b,

  • but the researchers have given it an edgier nickname: “The Forbidden Planet.”

  • It's about nine hundred light-years away, is smaller than Neptune,

  • and has a mass of about twenty Earths, but it gets its nickname from its orbit.

  • This planet is super close to its star, orbiting it every 1.3 days.

  • And that puts it in an area astronomers call theNeptunian Desert.”

  • This is the region right around a star

  • where scientists have only ever detected a handful of Neptune-like planets.

  • They aren't totally sure why these worlds are missing from these regions,

  • especially because they can contain other kinds of planets,

  • like hot Jupiters and super-Earths.

  • But it may be that they lost their battles against their stars' intense radiation.

  • Planets like Neptune have thick atmospheres, but when they get too close to their stars,

  • the stellar radiation heats up those atmospheres, and they probably just drift into space.

  • This hypothesis is supported by the fact that astronomers have observed similar planets

  • right at the edge of the Desert quickly losing their atmospheres.

  • So it seems likely the situation could be even worse for objects closer in.

  • So things don't look so good for the Forbidden Planet,

  • which is about 20x closer to its star than Mercury is to the Sun.

  • But somehow, it's survived.

  • Scientists are studying two main possibilities for how this happened.

  • One is that the planet formed farther out and drifted inward after its star's most active period.

  • That would have allowed the planet to avoid a lot of the high-energy X-rays

  • that would have heated its atmosphere.

  • Alternatively, the planet could have been saved

  • by having an especially massive core,

  • which would have helped it keep a gravitational hold on its atmosphere.

  • The case isn't closed, but scientists will keep looking into these possibilities.

  • And, they'll be on the lookout for other forbidden planets.

  • Because understanding where these worlds live and how they got into their orbits

  • can help us pin down models of solar system evolution.

  • Much closer to home, other scientists have been having their own struggles

  • with harsh planetary environments.

  • Except, their challenge is to figure out how people will breathe on Mars.

  • Until now, humans have either taken their own supply of oxygen to space,

  • or generated it from water molecules.

  • But hauling around oxygen or water gets pretty heavy and expensive.

  • It would also be completely impractical for sustaining a future settlement on Mars,

  • a planet whose atmosphere is mostly carbon dioxide.

  • But last month in Nature Communications,

  • a team of engineers announced they may have found a solution.

  • And their inspiration came from an unlikely place: comets.

  • Comets are one of the few places in space where we see molecular oxygen, or O2.

  • And for a couple of years, we've known about the strange chemical reaction that produces it.

  • It begins when a comet heats up, and water molecules on its surface evaporate.

  • Then those molecules get picked up by streams of particles radiating off the Sun,

  • and they slam back into the comet's surface.

  • At high speeds, those tiny collisions are enough

  • to rip oxygen atoms off other compounds on the comet and create O2.

  • In the study published last month,

  • the engineers wanted to figure out if this reaction could also happen with carbon dioxide.

  • After all, carbon dioxide has two oxygen atoms and is also found on comets.

  • But honestly, this was more of a long shot, because carbon dioxide molecules

  • form a straight line, with the oxygen atoms on opposite ends.

  • It would take some impressive molecular acrobatics to get those two oxygens to join together.

  • But the researchers are good researchers and at least wanted to test the idea.

  • So they created an experiment.

  • In it, they slammed carbon dioxide into a piece of gold foil.

  • Since gold has no oxygen atoms,

  • any oxygen produced would have had to come from the CO2.

  • And sure enough, the collision created oxygen!

  • That meant oxygen atoms were being torn off carbon dioxide,

  • transforming it into molecular oxygen and plain carbon.

  • This is an extremely unusual kind of reactionbut it's also promising.

  • Although the particular reactor used in this experiment

  • only made one or two oxygen molecules for every hundred molecules of carbon dioxide,

  • it proves that this type of chemistry is possible.

  • Scientists are optimistic that this process could be scaled up

  • and could eventually help give explorers a source of breathable air on Mars.

  • And if nothing else, they point out that we just learned something really cool with comets.

  • Space research is constantly challenging us to look for the exceptions to the rule.

  • From unexpected reactions and forbidden planets, we can learn a lot by studying the oddballs.

  • This episode of SciShow Space News is brought to you by our patrons on Patreon,

  • including today's President of Space,

  • who is no oddball, just an awesome guy, Matthew Brant.

  • Thanks, Matthew!

  • If you want to learn how to support SciShow

  • and help us bring you more news like this, you can go to patreon.com/scishow.

  • And to our current patrons, thanks for everything you do.

  • [♩OUTRO]

[♩INTRO]

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"禁断の惑星 "と呼ばれている (They're Calling It "The Forbidden Planet")

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    林宜悉 に公開 2021 年 01 月 14 日
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