You may have heard of Mercury rising in the morning sky, but today’s news is that Mercury is shrinking. The latest word from NASA is that images they’ve captured of the planet closest to the sun shows that it has gotten even smaller, but why? Mercury is only a bit larger than Earth's moon, so it is not that big to begin with.
Fox News on March 19 is calling Mercury “the solar system's shrunken head.” The planet is scorched from the sun and just like things that heat up here on earth, it contracted from the heat. What's different is that Mercury has contracted into itself even more than data first indicated.
According to the latest data, some spots on the planet have lost as much as four miles in elevation. This information was captured by NASA’s MESSENGER spacecraft. In the 1970s the Mariner spacecraft first captured images of giant cliffs, which were created during the shrinking process.
William McKinnon of Washington University in St. Louis said this latest data has helped solve that mystery of the towering cliffs on the planet's surface. Unlike Earth, which is made up of many plates, Mercury has one solid shell for a crust. The planet’s iron core has cooled off through the billions of years since Mercury was formed. The shrinking has cracked that crust, which moves forming the cliffs seen on the images.
Because the planet is contracting, signs of this is all over the surface of Mercury. The crust has cracked, shifting to accommodate the smaller size of the planet. This creates cliffs, some of great size. Paul Byrne of the Carnegie Institution of Washington and the Lunar and Planetary Institute said:
"Some of these things are really, really big. There are some truly gargantuan cliffs on Mercury."
He also said that the greater the planet’s shrinkage the greater the iron core of a planet. It appears that Mercury’s iron core is much bigger than first realized.