At several points in human history, short-sighted people
have prematurely declared the end of the age of discovery. In 1900, the
otherwise brilliant physicist, known to history as Lord Kelvin, allegedly claimed
that “there is nothing new to be discovered in physics now; all that remains is
more and more precise measurement.” Five years later, an obscure patent clerk
named Albert Einstein seemingly wandered out of the woods to publish something
called the “Theory of Relativity.” But Lord Kelvin shouldn’t beat himself up
too badly, the New York times suggested, in 1903, that it might take
mathematicians and engineers between one and ten million years to develop a
true flying machine – the exact same year the Wright brothers first took to the
sky. Actually, the New York Times has something of a history of being caught
with their foot in their mouth, claiming in 1920 that a rocket would never be
powerful enough to escape Earth’s atmosphere.
The reasons for these hilariously bad predictions are
debatable. It could be that the predictors had doubt in the cleverness of mankind or
fear of the unknown. It might even be that the people we remember for their
lack of prescience were simply overconfident in the scientists that came before
them, assuming that with such brilliant minds at work for so long, we must have
completed all the work that isn’t really, very, ridiculously hard. The truth,
however, is that the amount of stuff we don’t know is kind of incredible. Case
in point: our own solar system.
If you think we have a pretty good understanding of things
like our sun, moon, and planetary neighbours, you’ve been misled by overconfident
elementary school maps of the solar system. If you don’t believe me, ask any of
the map-makers who, in 2006, had to scramble to remove a lonely snowball named
Pluto from the list of recognized planets. Although, now you might have a hard
time getting them on the phone because they’re probably trying to figure out
how to deal with the supposed real
ninth planet that astronomers at the Caltech found evidence of last week.
Yes that’s right. Only a decade after pulling out their
collective erasers, planet counters are preparing to adjust the planetary
census once again. Researchers Konstantin Batygin and Mike Brown
– the very man most responsible for downgrading
Pluto to a dwarf planet – reported on January 20 that they have very good
reason to believe we’ve been overlooking something substantial at the edge of
our star system. Apparently, somewhere in the darkness around 25 times further away as Pluto, lurks a planet that is 10 times the mass of the Earth. So how did we
miss it?
Well, for starters, saying it is 25
times further away than Pluto doesn’t really do justice to how distant this
thing actually is. Pluto is 7.5 billion kilometers (4.7 billion miles) away
from us. The New Horizons spacecraft, that has been sending us pretty pictures
of Pluto for the past year or so, took a decade to get there. Using our
fastest, most modern spaceflight technology, it would take at least half a
century to get to where the uncreatively labelled 'Planet Nine' is supposedly
hiding. A second, and related, reason we haven’t discovered it sooner, is that
when you get that far from Earth, the Sun isn’t much more than a rather bright
star in the blackness of a permanent night. That means that Planet Nine gets
very little light it can reflect back to our telescopes.
In fact, we still haven’t actually discovered Planet Nine;
we just have hints that it exists. Brown and Batygin have been looking at half
a dozen objects located in the Kuiper Belt – Pluto’s celestial neighbourhood –
and discovered that they are drifting around on a plane that is out of line
with the rest of our solar system, yet seemingly in line with some other object’s
gravitational force, strongly suggesting that something big and close by is bullying
them with its gravity. The astronomers used a computer model to see what the
gravitational effect of a large planet in the outer solar system would have on
these objects and the results matched what they observed exactly. It’s a bit
like looking at the ripples in a pond and inferring that something recently
fell in the water. You can’t be positive, but you can be pretty sure.
So all that we are waiting for now is our first sighting.
Brown predicts it could happen in the next five years, possibly. We can’t be
sure though. Planet Nine’s orbit – if it exists – is massive. It takes between
12,000 and 20,000 years to orbit the Sun and astronomers will have to look at
every piece of that orbit to find where it is. That is a lot of sky.
Thankfully, that gives us some time to think of a better name.