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Planet Ten orbits
beyond Neptune on
a different plane
to the other planets
are far enough away from the gravitational EXPER T C O M M ENT
attraction of the gas giants to be tilted away
from this plane, and are affected by interactions Colin Stuart
with one another. Astronomer and author
This angle, known as the inclination, can be
calculated. If the observed angle differs from the “All eyes are on the outer Solar System right
now. First, astronomers found tantalising clues
one calculated, then it’s possible that the smaller of a ninth planet beyond the orbit of Neptune.
KBOs are being pulled out of line by something “The most But now there might be a tenth, too.
more massive – potentially an undiscovered We shouldn’t really be surprised. The early
planet. This method is how the existence of the likely Solar System was a much more chaotic place
so-called Planet Nine was predicted last year. than the largely serene environment of today.
After analysing more than 600 objects in the Another planet is thought to have whacked
explanation into the Earth to form the Moon, for example.
PHOTOS: HEATHER ROPER/LPL, NASA/JPL-CALTECH/SWRI/MSSS/JASON MAJOR Kuiper Belt, the researchers found a discrepancy
of 8° at around 50AU away from the Sun. for our What’s more, computer models of Solar System
“The most likely explanation for our results formation work better if there were more than
is that there is some unseen mass,” said results is four gas planets to begin with. Today’s gas
researcher Kat Volk. “According to our planets were the gravitational victors in the
calculations, something as massive as Mars would that there Solar System’s childhood squabbles. Planets
be needed to cause the warp that we measured.” Nine and Ten, should they be confirmed,
were likely bullied into far-flung orbits.
The researchers say we may not have directly is some But why is it taking until now to find them?
observed the planet because we haven’t yet After all, we’ve found more than 4,000 planets
searched the entire sky for distant objects in unseen mass” beyond our Solar System. We don’t spot those
the Solar System. However, a chance may exoplanets directly – we look for changes in the
come in 2020 when the Large Synoptic Survey light from their host stars to infer their presence.
Telescope (LSST) is completed. For us to see a distant planet in our own Solar
“We expect LSST to bring the number of System, light has to trek from the Sun all the way
observed KBOs from currently about 2,000 out there and back to the Earth, fading all the
to 40,000,” researcher Renu Malhotra said. while. So they’re on the edge of what we can
“There are a lot more KBOs out there – we just seen with current telescopes. With the potential
have not seen them yet. Some of them are too Planet Ten, the task is even trickier due to its
far and dim even for LSST to spot, but because likely position close to the bright Milky Way.
Should the planets be found, more than
the telescope will cover the sky much more a decade since Pluto was knocked off its
comprehensively than current surveys, it should planetary perch, the textbooks will need
be able to detect this object, if it’s out there.” ripping up again.”
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