NASA, ESA, and H. Hammel (Space Science Institute, Boulder, Colo.), and the Jupiter Impact Team
In July, when an object hurtled into Jupiter's clouds and scarred its cloud tops for all to see, humans had another chance to thank their lucky planet that Jupiter orbits where it does. It can act as a kind of one-planet offensive line, protecting the inner-planet backfield.
Now, a team of Japanese and British astronomers is reporting -- again* -- that Jupiter also can turn these objects into moons, at least or a few years.
The team found that from 1949 to 1961, Jupiter captured comet 147P/Kushisa-Muramatsu, which fell into an irregular orbit around the gas giant. It marked the fifth incident astronomers have uncovered so far where Jupiter has gained, then quickly lost, a potential moon.
The comet in question made two full trips around the planet before it beat cosmic feet and headed out again.
Based on the other four instances where Jupiter has briefly captured an object that completes at least one full Jovian orbit, such events occur on average about once every 10 years, the astronomers calculate.
The results imply that "impacts on Jupiter and temporary satellite-capture events may happen more frequently than we previously expected," according to David Asher, a scientist with the Armagh Observatory in Britain.