Windy and cool today on Mars and on planetary radio. Radio.

Hi everyone, we're glad you've joined us for another edition of our show. I'm Matt Kaplan.

Cornell scientist Don Banfield may be the closest thing we have to a Martian weatherman.

He's our guest this week.

Bruce Betts tells us about a party in the sky in what's up, along with our new space trivia contest.

And as usual, we'll get started with Emily, who says when it comes to planets, size does

matter.

I'll be right back. Hi, I'm Emily Loch D'Alo with questions and answers.

A listener asked, since the larger planets in the solar system are made of gas

and the smaller ones are solid,

I wonder if there is a limit to how large a planet can be

before it can no longer remain solid.

It is possible in principle for there to be a solid planet as massive as Jupiter, but in reality this is unlikely. The answer to this question has more to do with the composition than the mass of the planets.

The reason that the most massive planets are also gas giants is because they are made primarily

of the most abundant stuff in the universe, hydrogen.

Less massive planets are made of less common elements, such as those needed to make ice or rock.

The gas giants are fluid, not solid because hydrogen does not liquefy or

solidify under the pressures and temperatures found in the planet's interiors. Of course, even

Earth is not entirely solid.

Deep below the solid crust and mantle is a fluid core.

Are you confused yet?

To understand more about what makes planet solid, liquid, or gas, stay tuned to planetary radio.

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