The Planet Mercury Has Been Shrinking—More Than Scientists Expected
The solar system's smallest planet has gotten smaller still.
Mercury, the solar system's smallest planet, has contracted significantly over the past 4.5 billion years, according to a new study in Geophysical Research Letters. Scientists were surprised by the extent of Mercury's shrinking, which could be up to 30% more than previously thought. The findings come from data gathered by the MESSENGER spacecraft, which studied Mercury between 2011 and 2015.
MESSENGER used its laser altimeter and dual-imager to map shortening structures—distortions in the surface caused by the planet's contraction. However, these structures were often obscured by craters and rocks, making their detection challenging. By combining two-dimensional images taken at different angles, scientists were able to generate a detailed terrain map of Mercury, allowing them to infer the location and reach of shortening structures that were previously hidden.
This new understanding of Mercury's shrinking could impact our knowledge of how rocky worlds like the moon and Mars formed, as well as similar planets in distant solar systems.
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