11 New Moons of Jupiter Found
A team of astronomers has found 11 new moons around Jupiter, bringing the total number of Jovian satellites to 39.
Jupiter now has more known satellites than any other planet. Saturn is second with 30. Uranus has 20.
Jupiter’s newest additions were confirmed by the International Astronomical Union and announced Thursday. They were first detected in December by astronomers David Jewitt and Scott Sheppard of the University of Hawaii and Jan Kleyna of Cambridge University using the Canada-France-Hawaii telescope, a 3.6-meter optical telescope that sports one of the largest digital cameras in the world.
The satellites are all tiny compared to Jupiter’s “Big Four” moons--Io, Europa, Ganymede and Callisto, which were originally spotted by Galileo in 1610.
Those hulking bodies are thousands of miles across; the newly discovered satellites are between 1 and 2 miles across. The new satellites are thought to be rocky, like asteroids or planetesimals--the small chunks of dust, rock and frozen gas that coalesced into planets as the solar system formed or were ejected into distant reaches of the solar system to become comets.
The new satellites are called “irregulars” because they have looping, angled and eccentric orbits. Unlike the Big Four, the newly discovered satellites spin in the opposite direction of Jupiter. Jupiter has five families of satellites, differing in size and orbit type.
After Galileo’s work, four new satellites were found around Jupiter by the Voyager spacecraft and only nine more moons were found by observers on Earth, all in the 20th century. The work was painstaking: Astronomers looked for moons by scanning photographic plates of the night sky under microscopes.
Now, the search has become much easier because digital information captured by telescopes can be analyzed quickly. The team that made this discovery found 11 moons last year as well.
“There’s kind of a revolution going on,” Jewitt said. “Now we do it all by computers.”
They expect Jupiter will keep them busy for some time.
“We think there are many, many more to be found. Maybe 100,” Jewitt said.
The team is not out to simply count moons.
Because it approaches the size of the smallest stars and has so many things orbiting it, Jupiter is often referred to by astronomers as a mini solar system. Understanding how Jupiter acquired its strange collection of satellites could lead to a better understanding of how our solar system formed as well, Jewitt said.
A chief question is how Jupiter acquired so many satellites. Did its heft--300 times the mass of Earth--allow it to wrest them from an orbit around the sun? Did some form from the same dusty disks that spawned Jupiter and Earth? Were they speeding through the solar system and only captured after a huge gassy atmosphere that may have existed around Jupiter slowed them down? Are some of the tiny objects the shattered remains of bigger moons?
Said Jewitt: “We really don’t know what’s going on.”
