Page 12 - BBC Focus - August 2017

DISCOVERIES
This angle, known as the inclination, can be
calculated. If the observed angle differs from the
one calculated, then it’s possible that the smaller “THE MOST
KBOs are being pulled out of line by something
more massive – potentially an undiscovered LIKELY
planet. This method is how the existence of the
so-called Planet Nine was predicted last year. EXPLANATION
After analysing more than 600 objects in the FOR OUR
Kuiper Belt, the researchers found a discrepancy
of 8° at around 50AU away from the Sun. RESULTS IS
“The most likely explanation for our results is
that there is some unseen mass,” said researcher THAT THERE
Kat Volk. “According to our calculations,
something as massive as Mars would be needed to IS SOME
cause the warp that we measured.”
The researchers say we may not have directly UNSEEN MASS”
observed the planet because we haven’t yet
searched the entire sky for distant objects in the
Solar System. However, a chance may come in
2020 when the Large Synoptic Survey Telescope
(LSST) is completed.
“We expect LSST to bring the number of
observed KBOs from currently about 2,000 to
40,000,” researcher Renu Malhotra said. “There
are a lot more KBOs out there – we just have not
seen them yet. Some of them are too far and dim
even for LSST to spot, but because the telescope
will cover the sky much more comprehensively
than current surveys, it should be able to detect
this object, if it’s out there.”
12
Planet Ten orbits
beyond Neptune on a
different plane to the
other planets
EXP E R T C O M M E N T
Colin Stuart
Astronomer and author
“All eyes are on the outer Solar System right now. First,
astronomers found tantalising clues of a ninth planet
beyond the orbit of Neptune. But now there might be
a tenth, too.
We shouldn’t really be surprised. The early Solar System
was a much more chaotic place than the largely serene
environment of today. Another planet is thought to have
whacked into the Earth to form the Moon, for example.
What’s more, computer models of Solar System formation
work better if there were more than four gas planets to
begin with. Today’s gas planets were the gravitational
victors in the Solar System’s childhood squabbles. Planets
Nine and Ten, should they be confirmed, were likely bullied
into far-flung orbits.
But why is it taking until now to find them? After all,
we’ve found more than 4,000 planets beyond our Solar
System. We don’t spot those exoplanets directly – we look PHOTOS: HEATHER ROPER/LPL, NASA/JPL-CALTECH/SWRI/MSSS/JASON MAJOR
for changes in the light from their host stars to infer their
presence. For us to see a distant planet in our own Solar
System, light has to trek from the Sun all the way out there
and back to the Earth, fading all the while. So they’re on
the edge of what we can seen with current telescopes.
With the potential Planet Ten, the task is even trickier due
to its likely position close to the bright Milky Way.
Should the planets be found, more than a decade since
Pluto was knocked off its planetary perch, the textbooks
will need ripping up again.”