How did Pluto and Sharon meet? We discuss this week on Planetary Radio.

I'm Sarah Al-Ahmed of the Planetary Society, with more of the human adventure across our solar system and beyond.

The question of how Pluto and Sharon, or Karen, formed their close-knit, tidily locked system,

has long puzzled scientists.

This week, a Dean Denton from the University of Arizona returns to explain her team's

new modeling that suggests a kiss and capture may solve this mystery. Then Bruce Betts, our chief scientist, joins me for a look at contact binaries in our solar system,

and a new random space fact in What's Up.

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you'll never miss an episode filled with new and awe-inspiring ways to know the cosmos

and our place within it. Today we're exploring the outer reaches of the solar system,

revisiting a world that continues to surprise us, Pluto. NASA's New Horizons mission flew by that system in 2015 and gave us

our first close-ups of that fascinating dwarf planet and its surprisingly complex system. What we saw was not just a

cold, distant rock, but a dynamic world with vast plains of nitrogen glaciers and a surprisingly large moon, Sharon.

Pluto has five moons in total, but Sharon is so large compared to Pluto that they're often

called a binary system. Sharon is about half the diameter of Pluto, which is really unusual

considering that planets' moons are usually much smaller in comparison.

This odd couple, orbiting each other at about 16 Pluto radii, has presented scientists with a

really fascinating puzzle. How did they form? And what processes led them to this really unusual

configuration, where Sharon is not only really close in size, but also orbiting

very close by and in a rather circular fashion. To help us unravel these mysteries, we're joined

...