A new study has suggested that Mercury, the planet closest to the sun, is shrinking as its radius has witnessed reduction by some 7 kilometers over the past four billion years.
The findings are based on data beamed back by NASA’s Messenger spacecraft.
Scientists Paul K. Byrne and Christian Klimczak of the Carnegie Institution of Washington used the images and topographic data of NASA’s Messenger spacecraft to build a comprehensive map of tectonic features.
According to the reports, the planet has shrunk more than what was estimated earlier. The map suggests that the planet shrunk substantially as it cooled, as rock and metal that comprise its interior were expected to. Scientists also say the findings also solve an apparent enigma about how Mercury evolved.
While elaborating upon the study, the researchers said that the older images of Mercury’s surface suggested that the rocky planet had barely shrunk despite cooling. But modelling of the planet’s formation and ageing could not explain that finding.
Co-author Steven A. Hauck of Case Western Reserve University says, “”With Messenger, we have now obtained images of the entire planet at high resolution and, crucially, at different angles to the sun that show features Mariner 10 could not in the 1970s.”
The first spacecraft sent to explore Mercury was Mariner 10. The spacecraft had gathered images and data over just 45 percent of the surface during three flybys in 1974 and 1975.
However, NASA’s Messenger, which was launched in 2004 and inserted into orbit in 2011, is providing much more data and information about the planet. It is set to complete its 2,900th orbit of Mercury later this month.
For studying the shrinking pattern of the planet, the researchers looked at tectonic features which result from interior cooling and surface compression. The features resemble long ribbons from above, ranging from 5 to more than 550 miles long. Scientists say, some of these are cliffs caused by thrust faults that have broken the surface and reach up to nearly 3.2 km high.
With the new data, the researchers were able to see a greater number of these faults and estimate the shortening across broad sections of the surface and thus estimate the decrease in the planet’s radius.
Researchers say, estimates suggest that the planet has contracted between 4.6 and 7 kilometres in radius.
“This is significantly greater than the one to maybe two kilometers reported earlier on the basis of Mariner 10 data,” Hauck said.
The findings of the study were published in the latest edition of the journal ‘Nature Geoscience Sunday’.