Mercury: Shrinking Rapidly

Mercury, the smallest planet in our solar system, is shrinking at a faster rate than previously predicted. While previous estimates suggest that Mercury has only shrunken by a few miles, scientists now believe it is shrinking up to 30 percent faster than anticipated. Furthermore, Mercury might have even shrunk by as much as 14.5 miles, edging close to 1% of its current radius.

While Mercury was a hotter planet 4.5 billion years ago when it was formed, its metallic core has cooled and contracted over the millenniums, causing warps to appear on its surface.

“Many bodies, like the moon and Mars, are shrinking nowadays,” said Gaku Nishiyama, a planetary scientist at the German Aerospace Center Institute of Space Research who led the study. “But in the case of Mercury, it can shrink more because of its large metal core.”

Understanding the rate that Mercury is shrinking can help us understand the rate that it is cooling.

Dr. Nishiyama and his team used photographs from the 2004 flyby of NASA’s Messenger spacecraft and recent digital models to analyze the surface of Mercury. Wrinkles that form as the planet shrinks were present as ridges and valleys.

The scientists hope to apply what they have learned about Mercury’s wrinkles to other celestial bodies.

Fortunately, later this year, the European Space Agency and Japan Aerospace Exploration Agency

will launch their BepiColombo mission, providing a close look at the rarely seen planet Mercury.