It's day. It's twice as long as it's year. Why is it so dense then it's got to have so much iron in its core to make it that heavy?

And Mercury certainly moves pretty quickly around the sun, but it's an odd little planet.

Hello and welcome to the supermassive podcast from the Royal Astronomical Society with me, science journalist Issyclarc and astrophysicist Dr. Becky Smethurst.

We are finally completing our tour of the solar system this month with a trip to Mercury.

I mean, it's about time. I actually, I looked back, right? Oh, no, don't. We first did Jupiter in March 2020. So it's only took us 18 months to do a trip around this sort of stuff. Well, how long would an actual mission time would take? It's not bad in terms of missions. Yeah. We're still quicker than most.

And I swear if anyone writes and be like, what about Pluto?

I'd be like, no, no.

Yeah.

Anyway, what do we know about Mercury?

And what is the latest mission on its way to study the planet further?

And as always, Dr. Robert Massey, the deputy director of the Royal Astronomical Society, is here. So, Robert, what is Mercury like as a planet? Well, you could sum it up as hot, small and close to the sun, or hot and cold and small and close to the sun. And in many ways, it looks a lot like our moon, if you look at all the photographs from space probes. has got a really bleak, created surface. And it's not that much bigger than the moon either.

It's only 5,000 kilometres across, got no atmosphere to speak of. And it also has this sort of like baked Alaska quality. So for those of us who ate that dessert in the 1980s, it's the closest planet to the sun. So it's very hot. It gets up to 400 degrees

C, but also, because there's no atmosphere, the shadow regions, it goes down to minus 200 C. So,

you know, minus 200 Celsius. Imagine this huge contrast in temperatures and there might even be

waterized at the poles. Now, one of the things people often ask is, you know, how can you see it

in the sky? Because it is one of the naked eye planets and it's definitely something that our ancestors would have seen, you know, and been aware of. But it's always a bit of a challenge because it's quite close to the sun in the sky as well as being close to the sun in reality. But as it happens, you can catch it before sunrise in early September, 2024. So if you're listening to this episode early on after it goes out, you've got a chance of being able to do that. You can also see it in the morning at the end of the year. I'm thinking of this from a UK and Northern Hemisphere perspective. It's reasonably bright. You need to know, it helps say one of the apps to find it. A good telescope shows you maybe a phase that changes like Venus does because it's moving between

the earth and the sun. So to do better than that, we really needed space probes. And after all,

that's what this episode is about to find out more about that. And you'll hear later.

What a perfect setup. Yes, Robert. We'll catch up with you later in the show for some more

questions and this month's stargazing tips. So if we turn to the history books,

Mercury is the messenger of the Roman gods zipping around from place to place, which is how the

planet got its name. And Mercury certainly moves pretty quickly around the sun, but it's an odd

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