Astronomy
Popular Science
Move Over Pluto: There's a New Planet 9 in Town
5.2.16
Personally, I’ve always lamented the loss of Pluto as a ‘real’
planet. Losing Pluto is like losing a
close friend who, despite knowing they weren’t good for you, you wanted to hold
on to for ‘old times’ sake’. Fortunately, just as we find ourselves moving on
from our weird planet-human relationship with ex-Planet 9, a new prospect emerges
on the horizon. Or rather, a prospective prospect. Researchers believe that
they have evidence of a new, better, larger Planet 9, one that would (for the
sake of our gentle hearts) not be torn away from us the way Pluto so cruelly
was. In a twist of fate, one of the lead
researchers to make this as of yet unconfirmed discovery is the self-proclaimed
‘Pluto-killer’ himself, Dr. Mike Brown at Caltech. Well, well, well, Mikey, looks like someone’s
come crawling back. All jokes aside, astronomers
Batygin and Brown have recently published in The Astronomical Journal describing their analysis of distant orbit
patterns that they say point to the existence of a new Planet 9, this one far
more massive than Pluto.
The Kuiper Belt, a region of space extending roughly 30-50 AU from
the sun (Earth is roughly 1 AU from that shining beacon in the sky), is the
cold, dark place beyond Neptune where Pluto and several other dwarf planets are
known to hang out. The Kuiper Belt consists largely of small bodies thought to
be remnants of the formation of our solar system. Astronomers have known for
some time now that there are several distant Kuiper Belt Objects (so-called ‘KBOs’)
whose orbits appear clustered together and closely related, although no successful
theoretical model had yet been proposed to account for these somewhat odd
observations. Batygin and Brown point
out that in light of the tightly confined perihelion* positions and orbital
planes of these KBOs, the likelihood of such clustering behavior being due
entirely to chance is only about 0.007%, indicating the need for an external force
to account for their behavior.
With these curious observations in mind, Batygin and Brown set out
to identify a physical cause for these unaccounted for patterns in KBOs. The authors were able to conclude, based on a
series of calculations and simulations, that a large planetary body with an
extended orbit (10,000-20,000 years) could appropriately explain the oddly
correlated movement of the KBOs. Furthermore, simulations have suggested that
the body causing such a perturbation of gravitational orbits would need to be
rather massive, certainly massive enough to be considered a proper planet.
Although not yet substantiated, the proposed existence of a new and
improved Planet 9 could lead the actual observation of this new planet sooner
rather than later or never. I guess this is also a good lesson for any ex-Pluto
enthusiasts out there; there are always more planets in the sky.
References:
Batygin, K., and Brown, M.E.,
Evidence for A Distant Giant Planet in The Solar System, The Astronomical Journal, 2016,
151, 1-12. DOI:10.3847/0004-6256/151/2/22
*Perihilion: point in a planet’s orbit at which it is closest to the sun.
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