From watching the surface activity, Scientists have known that Mercury has shrunk somewhat over it’s 4.5 billion year life. For several decades, however, the question has remained: how much is it shrinking by? From data gleaned from the 1970s, the assumed number was a mere 1 to 2 kilometers of radius. Newer thermal models suggested somewhere more between 5 and 10. We now have a better guess.
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NASA’s MESSENGER spacecraft is in orbit over the smallest planet, and has produced a comprehensive survey of the planets surface features. In March, Paul Byrne and his team from the Carnegie Institute used those maps to produce a better guess that Mercury’s radius has shrunk by between 4 and 7 kilometers over the course of 4.5 billion years.
“We were looking at this independently…but it happened to be that the value we gor is pretty much what the models had been saying all along”
-Paul Byrne, Team Lead
Knowing that the thermal models are pretty close to accurate is great news for planetary scientists looking to understand our smallest planet better.
“Now that we can show that the models are more robust than we had thought…we can start looking at what the models are telling us about the interior of the planet, which we can’t otherwise get”
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