47P/Kushida-Muramatsu, is the fifth body known to have been drawn by Jupiter (pictured) from its orbit around the Sun.
Credit: ESA/NASA
SYDNEY: Jupiter’s gravity captured a comet in the mid-20th century, holding it in orbit as a temporary moon for 12 years.
The comet, named 147P/Kushida-Muramatsu, is the fifth body known to have been pulled by Jupiter from its orbit around the Sun.
The discovery adds to our understanding of how Jupiter interferes with objects from the ‘Hilda group’, which are asteroids and comets with orbits related to Jupiter’s orbit.
Along for the ride
“Our results demonstrate some of the routes taken by cometary bodies through interplanetary space that can allow them either to enter or to escape situations where they are in orbit around the planet Jupiter,” said researcher David Asher, an astronomer at Armagh Observatory in Northern Ireland.
He presented his findings today at the European Planetary Science Congress in Potsdam, Germany.
Comets from the Hilda group have been seen in collision courses with Jupiter for over 15 years. Most fly by without striking the planet or becoming satellites, but there have been some notable exceptions. Some astronomers have speculated that an Earth-sized black scar, which appeared on Jupiter’s surface in July, could have been from a Hilda group comet slamming into the gas giant.
Shoemaker-Levy 9, the first comet found orbiting Jupiter, is thought to have remained trapped by the planet for over 50 years. It was destined for an explosive end, though. The powerful effect of Jupiter’s gravity tore it into 20 fragments – some up to 2 km across – which plunged into the planet in 1994.
New moon in 2086
Asher’s team set out to find out how often Hilda comets became moon-like satellites of Jupiter. They modelled possible paths of 18 comets, searching for those that completed at least one whole orbit of Jupiter.
Hundreds of possible paths were calculated for 147P/Kushida-Muramatsu, based on tracking observations collected over the past nine years. In all cases, between 1949 and 1961 two full revolutions around Jupiter were completed. This 12-year-long journey is the third longest orbit found to date. Strikingly, Kushida-Muramatsu escaped the fate of Shoemaker-Levy 9, and was thrown back into orbit around the Sun.
The researchers have identified a future moon too. Comet 111P/Helin-Roman-Crockett is predicted to complete six laps of Jupiter between 2068 and 2086.
future paths
what's the possibility of one of the comets or asteroids redirected at us ?
Jupiter redirecting objects to earth
It is always possible that some object could be directed our way by Jupiter, but the vast majority the data shows that Jupiter acts more like a vacume that sweeps objects out of our solar system to protect us from many possible hits. Jupiter is often cited as the reason why we exist today due to the few hits from celestial objects compared the avearage place in the galaxy.
Conservation laws?
It would be nice if the article explained how the capture worked. Normally a minor body picks up enough speed (conservation of energy) coming in to leave again.
Now admittedly this is at least a 3 body problem (sun jupiter and comet) so I'm sure some form of energy loss to Jupiter is possible. But I'd like to udnerstand.