What's Inside Mercury?
Written by Fraser Cain
Interior of Mercury
Look at photographs of Mercury and you'll see a world very similar to our own Moon. It's desolate and rocky, pounded by impact craters and blasted by the constant radiation of the Sun. But if you could peek below the surface, what would you find inside Mercury?
Although Mercury looks like the Moon, it's internal composition is different. Mercury is much denser. And if you could actually set foot on both the Moon and Mercury, you'd know right away that there's a big difference. The force of gravity on Mercury is 38% of what you'd feel on Earth. In fact, that's very similar to what you'd feel if you stood on Mars. And Mars is much larger and more massive than Mercury.
Just like Earth, the surface of Mercury is a thin crust that covers an interior mantle and core. But unlike Earth, Mercury has no plate tectonics. On our planet, the crust floats above the mantle, and cracks and shifts. But on Mercury, the crust is one solid shell surrounding the mantle. Mercury is believed to have a crust measuring between 100 and 300 km thick.
Beneath this crust is Mercury's mantle. It's a shell 500-700 km thick that surround Mercury's core. But perhaps the biggest different between Earth and what's inside Mercury is it's core. Earth's core is a ball of iron around 3,400 km across, accounting for about 17% of the volume of the planet. But Mercury's core is 3,600 km across, accounting for 42% of the volume of the planet.
Astronomers recently learned that Mercury's core is liquid and not solid, as originally theorized. They learned this by bouncing radio signals off of Mercury's surface, measuring how long they took to return. They discovered that Mercury's movement had a wobble, similar to the difference you might see between spinning a raw egg and a hard-boiled egg. In this case, the liquid "sloshing" around inside Mercury is molten iron.
We have written many stories about Mercury here on Universe Today. Here's an article about a the discovery that Mercury's core is liquid. And how Mercury is actually less like the Moon than previously believed.
Want more information on Mercury? Here's a link to NASA's World Book on Mercury, and here's NASA's Solar System Exploration Guide to Mercury.
We have also recorded a whole episode of Astronomy Cast that's just about planet Mercury. Listen to it here, Episode 49: Mercury.
Dentro de lo que es el mercurio?
Filed under: Astronomy
