Molten metal sloshing around in Mercury’s core is creating a magnetic field that is similar to that of Earth’s — a shocker for scientists who didn’t think the planet was big enough to have a liquid core.
Scientists had assumed that like all the other rocky planets in the solar system, Mercury’s innards were solid, but NASA’s MESSENGER spacecraft — which crashed into the surface of the planet on April 30 — has sent back data that confirms Mercury has a liquid core, according to a Space.com report.
MESSENGER had been in orbit around Mercury for four years — far longer than the one year scientists had expected it to last when it was launched back in 2004 — and has collected more data on the planet than any other mission. Mariner 10 paid a visit four decades ago, but it was only a fly-by — although the spacecraft did first show that Mercury had a magnetic field.
But how Mercury could have a magnetic field was a mystery. It wasn’t large enough to host liquid metal for this long, as if it had liquid metal in its core, the small amount would have cooled quickly in the planet’s evolution. But MESSENGER confirmed that it does indeed have a liquid core, so scientists will have to rethink their theories on the planet’s development.
Mercury’s magnetic field isn’t strong — it’s a hundred times weaker than our own here on Earth.
Mercury is the smallest planet in our solar system and the closest one to the sun out of all of the eight planets. Despite its magnetic field, Mercury has no atmosphere to retain temperatures, which means its temperature variations are the largest in the solar system. Temps dip to a low of -280 degrees Fahrenheit at night to a broiling 800 degrees during the day.