Today’s post is part of a special series that first appeared on Planet Pailly. Every Thursday, we take a look at a new and interesting scientific term to help us all expand our scientific vocabularies together. Today’s word is:
Since the Solar System formed 4.5 billion years ago, Mercury has decreased in size by about 11 kilometers in radius. How do we know this? By studying wrinkly features on the planet’s surface called lobate scarps.
Mercury’s interior is cooling off, and as it cools, the planet shrinks. Unlike Earth, Mercury doesn’t have active plate tectonics, so the planet’s surface is forced to contract like a deflating balloon. Lobate scarps are long, winding ridges standing over the still deflating landscape.
Recent data from the MESSENGER space probe has allowed scientists to measure the height of these scarps. From those measurements, they’ve extrapolated the size Mercury used to be compared to the size it is now.
And it just so happens that these measurements match the theoretical predictions for how much contraction a planet like Mercury should experience due to heat loss. It’s nice when theory and observation agree. It means we’re doing something right.
Article by James Pailly.
To read all the articles in the ‘Sciency Words‘ series, visit the Planet Pailly blog.