Astronomers Stunned by a Tiny World With an Atmosphere

天文学家对拥有大气层的小型世界感到震惊

New Scientist Podcasts

2026-05-06

21 分钟
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Episode 366 A Pluto-sized object in the outer solar system has shocked scientists. It’s so tiny that it shouldn’t have an atmosphere - but it does. Object 2002 XV93, known as a plutino, is a small rock floating about in the Kuiper belt - a doughnut-shaped region of icy objects out near Pluto. What’s surprising is that many dwarf planets bigger than this object can’t hold an atmosphere, so it’s a mystery how this is even possible. This discovery comes as the decades-long debate about Pluto begins to bubble up again. Pluto was demoted from its planet status in 2006. But now NASA Administrator Jared Isaacman is reigniting the debate - on a controversial mission to make Pluto a planet again. So with this mysterious object and its unexpected atmosphere, plus the chance of Pluto being reinstated, do we need to change how we define planets? Is everything just a planet now?  Rowan Hooper and Penny Sarchet are joined by Jacob Aron and James Woodford to discuss the many ramifications of this new finding. To read more about these stories, visit https://www.newscientist.com/ Learn more about your ad choices. Visit megaphone.fm/adchoices
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  • Sometimes it's good to leave it all behind.

  • So for this episode, we're going far away, all the way to an object in the Kuiper Belt.

  • It's as far away as Pluto in the outer solar system.

  • And astronomers have been studying one of the rocks out there.

  • It's a big rock, but it's not a planet.

  • And they've been stunned to find that it has an atmosphere.

  • Can I go there now, actually, for a short break?

  • Yeah, this is a tiny thing.

  • It's only 500 kilometres in diameter.

  • And things that small are not supposed to be able to hold on to an atmosphere.

  • So that's the mystery.