While hunting for the elusive Planet X, astronomers have discovered 12 additional moons around Jupiter, bringing the grand total of the planet’s known satellites up to a whopping 79.
The new moons are all relatively small — between 1 and 3 kilometers (.6 to 1.8 miles) across, which is likely why they haven’t been spotted before, scientists said.
They were first seen in the spring of 2017 by researchers who have spent the last few years searching for Planet X, also known as Planet 9 — an object they expect to be Mars-sized or bigger.
They believe it lies in the distant solar system, as much as 100 times farther from the sun than is the Earth. (For reference, Pluto is about 30 times farther from the sun than Earth is).
Any object that far away will receive very little light from the sun that it can reflect back to telescopes on Earth, which is why the search has been so challenging, said Scott Sheppard, an astronomer at the Carnegie Institution for Science in Washington who led the work.
To aid them on this quest, the science team is using a four-meter telescope in Chile attached to the largest camera ever built.
It’s called the Dark Energy Camera, and it’s about the size of a smart car, Sheppard said.
Because the camera is so big, it can capture a much wider patch of sky in a single exposure than was previously possible.
“It allows us to be much more efficient than we’ve been in the past,” Sheppard said. “It used to be that one image was basically the area of a full moon in the night sky. Now we can cover twelve times that much.”
Sheppard and his colleagues are primarily focused on surveying the deep outer solar system, but a few years ago they realized that the Jupiter system was well positioned for them to take a closer look at its myriad satellites.
“It was kind of like trying to kill two birds with one stone,” Sheppard said. “We thought we might find a few more moons by covering the whole Jovian system in one exposure, which hadn’t been done before.”
The researchers deliberately picked fields to image that would allow them to see Jupiter’s moons without the bright light from the planet itself getting in the way.
They were able to determine which points of light in their images were Jovian moons because they moved across the sky at the same rate as their host planet.
“Anything that moved much slower would be a more distant object,” Sheppard said.
Their observations revealed the 12 never-before-seen moons. Eleven of them have been verified by representatives of the International Astronomical Union’s Minor Planet Center. The status of the 12th moon is still pending, although the researchers expect that it will be verified soon.
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SOURCE: LA Times, Deborah Netburn