Mercury's Radius Shrank by over 10 km: Japan Team

Tokyo, Sept. 10 (Jiji Press)--Since its birth around 4.6 billion years ago, Mercury's radius has shrunk by over 10 kilometers as the inside of the planet cooled down, a team from Japan's Hokkaido University has found.

The team's findings were published in the U.S. science journal Geophysical Research Letters on Thursday.

Mercury's radius currently stands at some 2,440 km. Observations by the U.S. space probe Messenger and other equipment have confirmed that there are many wrinkle ridges on the surface of the planet that formed as the ground contracted.

While attempts had been made to estimate the planet's shrinkage based on the length and other characteristics of such wrinkles, there was a possibility that the shrinkage was underestimated because the geological features were unevenly distributed.

Using a new analysis method, Gaku Nishiyama, a postdoctoral researcher at the university, focused on the possibility that the wrinkles may have been obscured by craters formed by meteor impacts and lava eruptions.

[Copyright The Jiji Press, Ltd.]