NASA Detects Comet That Slowed Down And Began Spinning In The Opposite Direction

Astronomers have made a rare and surprising discovery about a small comet, showing how activity on its surface can change the way it spins. Using NASA's Hubble Space Telescope, scientists found evidence that a comet not only slowed down but also reversed its direction of rotation for the first time ever observed, reported NASA.

This celestial body is known as Comet 41P/Tuttle-Giacobini-Kresak, or 41P for short. Scientists believe it originated in the Kuiper Belt. Later, due to Jupiter's gravitational influence, it settled into its current orbit and now orbits the inner solar system every 5.4 years.

Decline In Rotational Speed

After its close passage by the Sun in 2017, scientists recorded a significant change in its rotational speed. Data from the Neil Gehrels Swift Observatory in May 2017 revealed that the comet was rotating three times slower than in March 2017, when it was observed with the Discovery Channel Telescope at the Lowell Observatory in Arizona.

Change In Rotational Direction

Then, observations by the Hubble Space Telescope revealed another surprising finding. Images from December 2017 showed that the comet was spinning faster again, completing one revolution in about 14 hours. Previously, Swift data had recorded its rotation time as between 46 and 60 hours.

According to scientists, its speed first slowed to the point where it almost stopped, and then it began rotating in the opposite direction. This change was caused by gas jets emanating from its surface.

When a comet approaches the Sun, the ice on its surface heats up and turns into gas, escaping into space. These gas jets act like tiny thrusters.

According to David Jewitt of the University of California, Los Angeles, the streams of gas emanating from the surface act like tiny thrusters. If these jets are not evenly distributed, they can significantly alter the rotation of especially small comets.

They compared it to a swing-like toy, explaining that if it's spinning in one direction and is pushed in the opposite direction, its speed may decrease and eventually change direction.

Small Size, Big Impact

Hubble data also revealed the size of the comet's nucleus, which is about 0.6 miles (about a kilometer) wide. This is about three times the height of the Eiffel Tower. Its small size makes it more vulnerable to external influences like gas jets.

Rapidly Changing Nature

The study also found that the comet's activity has decreased over time. When it approached the Sun in 2001, it was quite active for its size, but by 2017, its gas emission capacity had decreased by almost tenfold.

This indicates that its surface is rapidly changing, possibly because its icy material is being depleted or a layer of dust is accumulating on it.

A unique opportunity for scientists

Comets typically undergo such changes over hundreds or thousands of years, but the rapid changes observed in 41P provide scientists with a rare opportunity to understand how these celestial bodies evolve over a human lifetime.

The findings of this study have been published in The Astronomical Journal.