New data has indicated that the Earth's sister planet, Venus, is slowing down, and scientists are stumped as to why, according to a CBC News report.
Scientists were surprised to learn from the European Space Agency's Venus Express orbiter, used to map Venus' surface, that Venus is rotating 6 and a half minutes slower than it was 16 years ago.
Sue Smrekar, a researcher at NASA's Jet Propulsion Lab in California initially thought something was wrong with the data.
"But after looking at the data I was convinced the result is correct. It means something has slowed the rotation of the planet and we don't really know what that is," she said.
Different theories are being proposed as to why Venus' rotation speed has drastically dwindled.
The length of a day on Earth can change by a millisecond depending on winds, tides and temperature, and Smrekar says something similar could be happening with Venus.
The planet, which rotates the opposite way of most planets , has a dense atmosphere that has more than 90 times the pressure at sea level on Earth.
"This generates high-speed weather systems on Venus, which are likely to be the primary candidate changing the planet's rotation rate through friction with the surface," says Smrekar.
However a Belgium team concluded that those kinds of changes would average themselves out over long periods of time.
The effects of other planets on Venus could also be playing a role.
Read CBC News report here: http://bit.ly/yKlYiS
This story was updated to clarify that Venus rotates differently than most other planets