Astronomers have discovered two new moons orbiting the planet Jupiter. In total, scientists have discovered 69 moons orbiting Jupiter.
Jupiter Is A Microcosm Of The Solar System
More than 300 times larger than Earth, Jupiter is the largest planet in the solar system and — thanks to its massive size – functions a bit like a mini solar system itself. Its collection of moons ranges in size and time of orbit.
The gas giant's collection of moons includes some of the largest bodies in the solar system. A few are even large enough that they would be considered dwarf planets if they were in orbit around the sun. Others are much smaller than the Earth's own.
The moons' orbit can take anywhere from as little as 7 hours to as long as a thousand days depending on how far they are away from the planet.
Late To The Party
One of the interesting things about Jupiter's moons is that the majority of them spin in a retrograde fashion, opposite of the planet's spin, which leads scientists to believe that they were passing asteroids that were caught in the planet's gravity. Only the innermost 15 spin in prograde — in the direction of Jupiter's own rotation — and are more likely original.
Jupiter's New Moons
Jupiters newest moons were discovered by astronomers Scott Sheppard, David Tholen, and Chadwick Trujillo who were searching for more distant objects. The moons just happened to be captured in their images.
As for as the bodies themselves, they aren't particularly impressing measuring only about 0.5 to 1.5 miles in size. Given their distance from the planet, about 13 million miles, it is likely that these were passing asteroids that were caught in the pull of the planet's gravity.
Despite the nature of these moons, their discovery is interesting because the orbit of Jupiter's moons can make them hard to track. There have been cases where astronomers thought they had discovered new moons only to find they had stumbled on so-called "lost moons" which had previously been recorded.
In order to ensure that these were new moons, the scientists observed the moons for over a year tracking their movements and eventually confirmed these were previously undiscovered objects. In total, this brings Jupiter's moon collection to 69. It is the planet with the most moons in the solar system though Saturn comes close with 62 moons.