NASA Just Found a Comet That Defies the Laws of Science

Science News
Thursday, 11 January 2018 - 10:59AM

If you thought comets were just flashy rocks that show up every now and then to entertain stargazers, you're in for a surprise.


Each comet is a hunk of ice, rock, and gas that orbits the sun, and astronomers recently caught one doing something they'd never seen before: comet 41P, also known as Tuttle-Giacobini-Kresák, usually spins at a speed of one full rotation every 20 hours, a little less than Earth.


This May, however, the comet's rotation had slowed to one full spin every 46 to 60 hours. The reason? Jets.

When a comet gets close to the sun, the ice on its surface heats up, causing it to explode into jets of gas, ice, and dust. These jets create a small, temporary atmosphere around the comet called a coma, which is also the source of the comet's tail.


The amount of surface area on a comet that has active jets is usually around 3 percent, but 41P's surface was observed to be 50 percent jets. The force created by these jets appears to have slowed the comet's rotation to almost half its previous speed.

All this information comes to us from the Swift spacecraft, which has been "monitoring comets, studying stars hosting exoplanets, and catching outbursts from supernovas, neutron stars and black holes" for the past 13 years. According to Dennis Bodewits, who presented the new findings yesterday at the American Astronomical Society:

"The previous record for a comet spindown went to 103P/Hartley 2, which slowed its rotation from 17 to 19 hours over 90 days. By contrast, 41P spun down by more than 10 times as much in just 60 days, so both the extent and the rate of this change is something we've never seen before."

Astronomers will be keeping an eye on 41P and watching it for any other stranger behaviors in the future.