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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.

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