Thread by @ThePlanetaryGuy

I need you to know I'm being completely serious here.

We have no idea what's inside Uranus.

We really don't have a clue what's inside this or there other "ice giant", Neptune.

It's possible that there's a rocky interior, perhaps at least as large as Earth. There might be a water–ammonia ocean above that rocky centre, topped with a thick atmosphere.

But we don't know.

Uranus and Neptune are the outer Solar System's Venus -- fascinating, largely unexplained, but to be honest pretty much ignored in the modern era of planetary exploration.

I am *so* happy we're going back to Venus.

But we can't forget the Ice Giants.

But as difficult as Venus' surface is to study, its middle atmosphere is clement and it's fairly straightforward to orbit.

But Uranus is ~20 times farther from the Sun than Earth. Neptune, ~30 times farther.

And that makes them *extremely* technically challenging destinations.

So how do we figure out what's inside?

An orbiter could take geophysical measurements to help us understand the interior structure: the ratios of gases to silicates to metals.

If we want to take direct measurements of, say, composition and atmospheric dynamics, however...

...then we need to send a probe as deep as possible into Uranus.

We've sent probes into Jupiter and Saturn's moon Titan. They encounter terrific temperatures and pressures as they descend, but some measurements have *got* to be done in situ.

Difficult? Yes.

Expensive? Very.

Worth doing? Absolutely.

Postscript: the planet's name in English sure does lend itself to lots of jokes, and I think life is too short not to lean into them.

But never let a funny name get in the way of tackling some of the major questions about planets we have yet to answer.