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  • These alien worlds, about 40 light-years away from Earth, are believed to be the most likely

  • place for biological life beyond our solar system.

  • TRAPPIST-1 is a dwarf star with at least seven exoplanets orbiting around it.

  • The full system was discovered in 2017, and it marked a monumental milestone for astrophysics,

  • because at the time, it was the greatest number of Earth-like planets

  • ever found around a single star.

  • We now know more about this planetary system than any other beyond our own, and it could

  • help us understand the potential for other life in our universe.

  • Astronomers first discovered TRAPPIST-1 in 1999.

  • They classified it as an ultra-cool dwarf star, which means its temperature is low enough

  • that liquid water could likely survive on planets orbiting very close to it.

  • Over a decade later, scientists discovered the star was host to three exoplanets using

  • the Transiting Planets and Planetesimals Small Telescope aka TRAPPIST.

  • And then, after about a year, NASA's Spitzer Space Telescope helped reveal even more exoplanets.

  • Scientists realized that the TRAPPIST-1 system also set a new record for the greatest number

  • of planets in the so-called habitable zone.

  • Experts say that almost every normal star has a habitable zone, which is the range of

  • distance from its star where temperatures are right for water to remain liquid.

  • Four of the seven TRAPPIST-1 exoplanets are in this zone.

  • Well, technically the jury's still out on where planet d lies, which is an indication

  • of just how new this discovery is.

  • The Hubble Space Telescope conducted a spectroscopic survey to learn more about

  • the habitability of the planets.

  • It revealed that planets d, e and f don't seem to have

  • puffy, hydrogen-rich atmospheres like gas giants.

  • This is good news in the search for life because hydrogen is a greenhouse gas and can make

  • planets orbiting close to their parent star too hot and thus inhospitable.

  • Planets d, e and f instead appear to have atmospheres

  • similar to terrestrial or rocky planets.

  • So far, scientists consider planet e to be the most Earth-like in terms of its estimated

  • radius, mass and the amount of radiation that it receives from its host star, and they believe,

  • of all the planets, it's the most likely to have liquid water on its surface.

  • That's not to say the other TRAPPIST-1 planets are devoid of water.

  • In fact, researchers found that some of the planets could have as much as

  • 250 times more water than Earth.

  • But too much water may be a bad thing.

  • Planets with too much water likely don't have any land and thus lack important geochemical

  • or elemental cycles necessary for sustaining complex organisms.

  • The thing is, the TRAPPIST-1 system is such a fresh discovery

  • and there is still so much we have to learn.

  • Astronomers are looking to the upcoming James Webb Space Telescope

  • to help better understand these alien worlds.

  • Unlike Spitzer, Hubble and Kepler, the Webb telescope has extended wavelength coverage

  • that will be able to detect atmospheric properties of the planets with greater precision.

  • But the new telescope won't begin its cosmic journey until the 2020s, so in the meantime,

  • astronomers will have to get creative to uncover more about TRAPPIST-1's life harboring potential.

  • If you're looking to learn more about space exploration and astronomical phenomena

  • be sure to watch this episode of Space Crafts.

  • And don't forget to subscribe to Seeker for all things science.

  • Thanks for watching!

These alien worlds, about 40 light-years away from Earth, are believed to be the most likely

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星球一號(Are the TRAPPIST-1 Planets Home to Life?)

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    joey joey 發佈於 2021 年 04 月 10 日
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