A long-standing uranium mystery gets an update.

This week on Planetary Radio.

I'm Sarah al-Ahmad of the Planetary Society,

with more of the human adventure across our solar system and beyond.

For decades, Uranus has baffled scientists.

Voyager 2's 1986 flyby suggested that the ice giant wasn't radiating any extra heat,

but new research has finally cracked the case.

I'll talk with Michael Roman, assistant professor at the Universidad Adolfo and Báñez in Chile,

and co-author on a new paper showing

that Uranus really is giving off more heat than it receives from the sun. We'll also celebrate the

discovery of a brand new moon around Uranus in this week's What's Up with our chief scientist, Bruce Betz.

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Uranus has a reputation, partly for its name that's the butt of endless jokes, but mostly because it's just plain weird.

This ice giant spins on its side, tilted nearly 98 degrees. That tilt gives it some of the

most extreme seasons in the solar system, with decades of daylight at one pole, while the other one is

locked in darkness. Its atmosphere is strangely bland compared to Neptune's stormy

skies, and yet it hides mysteries that we still don't fully understand. One of the strangest puzzles

was uncovered by Voyager 2 in 1986. Unlike Jupiter, Saturn, and Neptune, which all radiate more

heat than they received from the sun, Uranus appeared to be in perfect balance, giving off no excess heat at all.

We would say that this world seemed to be in thermal equilibrium. That made it a definite odd ball

among the giant planets, raising big questions about its history and interior. We expect our giant

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