Mercury (the planet)

The name Mercury has gotten attached to a lot of things--an element, a car company, a WNBA team--but the OG is the planet closest to the sun, named after the Roman god. This hot, barren, lifeless (or so we think) world may not seem like it' has much going for it, but it's secretly fascinating. CONTENT WARNING: If you're a planetary scientist who had something to do with booting Pluto, this will be an uncomfortable five minutes for you.

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Transcript

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Hey, here's a trivia question for you. What name belongs to a planet, a Roman god, an element, a former division of Ford Motor Company, and Phoenix, Arizona's WNBA team. If you said Saturn Yeah, it's it's it's not Saturn. It's Mercury. First planet from the Sun, chemical symbol HG on the periodic table, WNBA Championship finalist in 2025. So which of these are we talking about today? Well, we here at Five Minute Trivia love our planets. And Mercury is among the most lovable. It's so tiny and cute and bumpy. It's like a pet rock of planets. How could we not talk about it? We choose to go to the moon. Welcome to Five Minute Trivia, where we're making the world smarter five minutes at a time. I'm your host, R. M. Zuberi. In 2006, a bunch of self-important weenies at the International Astronomical Union collectively lost their minds when they kicked Pluto out of the solar system. We did a couple of episodes on Pluto last year. If you haven't listened to them yet, this might not be a bad time. Pluto's demotion left us with only one plucky little underdog planet. Unlike Pluto, there's no possibility that Mercury sees the same fate. Mercury is the real deal. Round planet with a proper orbit. It is tiny though, it measures about as far across as the continental United States. Mercury is the closest planet to the sun. Like Venus next door, it has no moons. Also, like Venus, a day on Mercury is longer than a year on Mercury. Yeah, you heard that right. It orbits the sun faster than it rotates around its own axis. Yeah, it moves so fast it reminded ancient Greeks of the fleet-footed messenger god Hermes. In fact, the planet is still called Hermes in Greek. The Roman name for Hermes is Mercury, and these guys felt so strongly about that name that they literally conquered half the known world, just to make sure we called it that. Prior to 2006, our solar system was made up of four rocky planets, four gas giants, and then one odd little ice ball. Now that Pluto is gone, thanks again, IAU, that messy little bit of bookkeeping went with it. Mercury is very similar to the planets near it, namely Venus, Earth, and Mars. Like Earth, Mercury is made up of a crust, a mantle, and an iron core. Unlike Earth, Mercury's core is huge relative to the size of the planet. Earth's core occupies about 55% of its radius. Mercury's is 85% of its radius. It's basically a ball of iron surrounded by dust. That dust on the surface also makes up Mercury's atmosphere. Now, technically, Mercury doesn't have an atmosphere. It has something called an exosphere. It's basically just a thin layer of molecules and elements kicked up from the surface by solar winds. The planet has just enough gravity to hang on to that exosphere, but it doesn't do much for the planet. What do we mean by that? Well, as the closest planet to the Sun, you'd expect Mercury to be hot. And the side facing the Sun gets really hot. During the day, the temperature reaches 800 degrees Fahrenheit. But what you probably wouldn't expect is that the side facing away from the Sun is absolutely frigid, like 300 degrees below zero. In other words, the difference between day and night on Mercury is more than a thousand degrees. That's because there are no greenhouse gases in the atmosphere to retain any heat at night. The absence of an atmosphere also means that asteroids and meteors won't burn up or get slowed down by anything. If some wayward rock enters Mercury's gravity, it'll get pulled in and slammed into the surface. So Mercury is absolutely pockmarked with craters. One of the largest known impact craters in the solar system is on Mercury, nearly 900 miles across. There are hundreds of these craters on Mercury, and they need names. Now we've been a little hard on the International Astronomical Union for Booting Pluto, and to be clear, they deserve every drop of venom spat in their direction for that, but credit where credit is due, they have gone to the trouble of naming every crater. Craters on Mercury are named after famous writers, artists, and composers. There are craters named for Maya Angelou, Beethoven, Walt Disney, Pablo Picasso, Khalil Gibron, Kurt Vonnegut, oh and my personal favorite, Chuck Berry. To qualify, an artist must have been famous for 50 years and then dead for three years before they're eligible for craterhood. So sadly it'll be a little while before we see a five-minute trivia crater. But if we keep it up, maybe we'll get off this planet and on to Mercury. That's our show this week. We'll see you next time, and thanks for listening.