At this point, I think the astronomy textbook publishers should just give up.
They’d like to tell you how many planets there are in the Solar System, they really
would.
But astronomers just can’t stop discovering new worlds, and messing up the numbers.
Things were simple when there were only 6 planets.
The 5 visible with the unaided eye, and the Earth, of course.
Then Uranus was discovered in 1781 by William Herschel, which made it 7.
Then a bunch of asteroids, like Ceres, Vesta and Pallas pushed the number into the teens
until astronomers realized these were probably a whole new class of objects.
Back to 7.
Then Neptune in 1846 by Urbain Le Verrier and Johann Galle, which makes 8.
Then Pluto in 1930 and we have our familiar 9.
But astronomy marches onward.
Eris was discovered in 2005, which caused astronomers to create a whole new classification
of dwarf planet, and ultimately downgrading Pluto.
Back to 8.
It seriously looked like 8 was going to be the final number, and the textbook writers
could return to their computers for one last update.
Astronomers, however, had other plans.
In 2014, Chad Trujillo and Scott Shepard were studying the motions of large objects in the
Kuiper Belt and realized that a large planet in the outer Solar System must be messing
with orbits in the region.
This was confirmed and fine tuned by other astronomers, which drew the attention of Mike
Brown and Konstantin Batygin.
The name Mike Brown might be familiar to you.
Perhaps the name, Mike “Pluto Killer” Brown?
Mike and his team were the ones who originally discovered Eris, leading to the demotion of
Pluto.
Brown and Batygin were looking to find flaws in the research of Trujillo and Shepard, and
they painstakingly analyzed the movement of various Kuiper Belt Objects.
They found that six different objects all seem to follow a very similar elliptical orbit
that points back to the same region in space.
All these worlds are inclined at a plane of about 30-degrees from pretty much everything
else in the Solar System.
In the words of Mike Brown, the odds of these orbits all occurring like this are about 1
in 100.
Instead of a random coincidence, Brown and Batygin think there’s a massive planet way
out beyond the orbit of Pluto, about 200 times further than the distance from the Sun to
the Earth.
This planet would be Neptune-sized, roughly 10 times more massive than Earth.
But why haven’t they actually observed it yet?
Based on their calculations, this planet should be bright enough to be visible in mid-range
observatories, and definitely within the capabilities of the world’s largest telescopes, like
Keck, Palomar, Gemini, and Hubble, of course.
The trick is to know precisely where to look.
All of these telescopes can resolve incredibly faint objects, as long as they focus in one
tiny spot.
But which spot.
The entire sky has a lot of tiny spots to look at.
Based on the calculations, it appears that Planet 9 is hiding in the plane of the Milky
Way, camouflaged by the dense stars of the galaxy.
But astronomers will be scanning the skies, and hope a survey will pick it up, anytime
now.
But wait a second, does this mean that we’re all going to die?
Because I read on the internet and saw some YouTube videos that this is the planet that’s
going to crash into the Earth, or flip our poles, or something.
Nope, we’re safe.
Like I just said, the best astronomers with the most powerful telescopes in the world
and space haven’t been able to turn anything up.
While the conspiracy theorists have been threatening up with certain death from Planet X for decades
now - supposedly, it’ll arrive any day now.
But it won’t.
Assuming it does exist, Planet 9 has been orbiting the Sun for billions of years, way
way out beyond the orbit of Pluto.
It’s not coming towards us, it’s not throwing objects at us, and it’s definitely not going
to usher in the Age of Aquarius.
Once again, we get to watch science in the making.
Astronomers are gathering evidence that Planet 9 exists based on its gravitational influence.
And if we’re lucky, the actual planet will turn up in the next few years.
Then we’ll have 9 planets in the Solar System again.
Planet 9 is a terrible name, so we need something better.
What should we call it?
Suggest your best ideas and I’ll pass them along to Mike Brown and his team.
In our next episode we talk about this Stephen Hawking approved probe to Alpha Centauri.
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