Share to ClassroomStudy: Mercury Lost More Size Than Thought
A new study says that Mercury, the smallest planet in our solar system, has lost more of its size than scientists believed. The planet has shrunk, or become smaller, about 30% more than earlier studies said. It may have lost up to 14 miles (23 kilometers) across. That is a lot for a planet that is only about 3,000 miles (4,900 kilometers) wide. The study was led by Gaku Nishiyama of the German Aerospace Center.
Mercury has been getting smaller for 4.5 billion years. Its hot iron center, called the core, is slowly cooling. As it cools, the planet gets smaller, and lines like wrinkles appear on the surface. Scientists count these wrinkles to measure the change. But the study found that many wrinkles may be hidden because space rocks hit the planet and covered them. The team used pictures from MESSENGER, a spacecraft from NASA (the US space agency), to make a detailed map.
Mercury is hard to study because it is very close to the Sun and very hot. Only two spacecraft have visited it so far. In November, a European and Japanese spacecraft called BepiColombo should start to orbit, or travel around, the planet. It will help check how much Mercury has shrunk. "We are quite excited," Nishiyama said.
