Scientists have determined that Mars has a magnetic twisted tail that is totally unlike anything else we see in the solar system. NASA was surprised to find that the tail that trails behind Mars is much more dramatically twisted than they had believed, and it may be causing the Mars atmosphere to thin even further.

Venus and Earth also have magnetotails, but the one trailing Mars appears to be very complex. NASA determined this based on its Mars Atmosphere and Volatile Evolution Mission (MAVEN) spacecraft. The tail seems to be a hybrid of the magnetotail found at Venus and the Earth’s, which is completely surrounded by its own magnetic field that is internally generated.

Scientists think this tail is twisted due to something called “magnetic reconnection,” which happened when Mars lost its magnetic field billions of years in the past. The planet left behind remnants of its magneticfield, which joins with solar wind to create the phenomenon.

“We found that Mars’ magnetic tail, or magnetotail, is unique in the solar system,” said Gina DiBraccio of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It’s not like the magnetotail found at Venus, a planet with no magnetic field of its own, nor is it like Earth’s, which is surrounded by its own internally generated magnetic field. Instead, it is a hybrid between the two.

“Our model predicted that magnetic reconnection will cause the Martian magnetotail to twist 45 degrees from what’s expected based on the direction of the magnetic field carried by the solar wind,” said DiBraccio. “When we compared those predictions to MAVEN data on the directions of the Martian and solar wind magnetic fields, they were in very good agreement.”