
Race to discover Planet Nine using astronomy and new computational techniques - sohkamyung
http://spectrum.ieee.org/aerospace/satellites/is-there-a-giant-planet-lurking-beyond-pluto
======
captaincrowbar
Anyone interested in the search should follow Brown and Batygin's Planet Nine
blog at [http://www.findplanetnine.com/](http://www.findplanetnine.com/)

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acqq
New And Better Data Disfavors A Giant World Beyond Neptune

[https://www.forbes.com/sites/startswithabang/2017/06/21/good...](https://www.forbes.com/sites/startswithabang/2017/06/21/goodbye-
planet-nine-new-and-better-data-strongly-disfavors-a-giant-world-beyond-
neptune/)

As the months passed since it was first proposed by Konstantin Batygin and
Mike Brown, they compiled additional evidence for it, and things were looking
rosy. But a new study by Shankman et al. has turned the evidence on its head,
disfavoring the planet's existence and uncovering a bias in the data itself.

[https://arxiv.org/abs/1706.05348](https://arxiv.org/abs/1706.05348)

"The clustered TNOs were detected across different and independent surveys,
which has led to claims that the detections are therefore free of
observational bias. This apparent clustering has led to the so-called "Planet
9" hypothesis that a super-Earth currently resides in the distant solar system
and causes this clustering. The Outer Solar System Origins Survey (OSSOS) is a
large program that ran on the Canada-France-Hawaii Telescope from 2013--2017,
discovering more than 800 new TNOs. One of the primary design goals of OSSOS
was the careful determination of observational biases that would manifest
within the detected sample. We demonstrate the striking and non-intuitive
biases that exist for the detection of TNOs with large semi-major axes. The
eight large semi-major axis OSSOS detections are an independent dataset, of
comparable size to the conglomerate samples used in previous studies. We
conclude that the orbital distribution of the OSSOS sample is consistent with
being detected from a uniform underlying angular distribution."

~~~
sohkamyung
Yes, I've heard of that. Some follow-up articles I've read [1] [2] say that
the evidence against (or for) Planet Nine is still inconclusive. But the
question should be settled one way or another: Planet Nine will either be
there or it won't.

[1] "Solar System survey casts doubt on mysterious 'Planet Nine'" [
[https://www.nature.com/news/solar-system-survey-casts-
doubt-...](https://www.nature.com/news/solar-system-survey-casts-doubt-on-
mysterious-planet-nine-1.22177) ]

[2] "Planet Nine Is Put on Trial in Absentia" [
[https://www.quantamagazine.org/planet-nine-is-put-on-
trial-i...](https://www.quantamagazine.org/planet-nine-is-put-on-trial-in-
absentia-20170627/) ]

~~~
moomin
They thought that about dark matter.

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mturmon
A nice update in the search for Planet Nine that touches on a lot of new
computational, survey-based, and modeling efforts to localize the planet.
Great level of detail.

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jagger27
I hope I get to see some New Horizons-esque images of it by the time I'm old
and grey.

Imagine its moons. Does it have rings? Does it have Trojans? Is it another
line of defence, a remote cosmic vacuum cleaner, like Jupiter? Maybe Clarke's
monolith lurks in its orbit.

I can't wait to find out.

~~~
honestoHeminway
Even more interesting, is this disturber of the cuiper belt, the responsible
one for the exstinction events (dinosaurs) that happened to our little world.

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everyone
This is awesome. Also I found a tiny nitpick

"But the early 1990s also brought a big breakthrough in an algorithm, known as
symplectic integration, that reduced computational times by an order of
magnitude."

then

"Because symplectic integrators don’t waste time rediscovering Kepler’s laws
over and over, they run orbital simulations hundreds of times as fast as older
methods do."

100 times as fast is two orders of magnitude.

~~~
ryanx435
Maybe,maybe not. Depends on what base you are measuring magnitude in.

In base 10, 100x is 2 orders of magnitude.

In base 2, the same speed up (written in binary: 1100100x) is between 6 and 7
orders of magnitude.

~~~
Armisael16
No one means any base other than base 10 when they use that phrase in casual
speech (without previously saying so).

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Robotbeat
If "Planet Nine" doesn't exist, that will be fitting Karma for those who
proposed it, since they developed the new definition of planet specifically to
exclude Pluto and any other planets like Pluto.

(I disagree with that definition as it made no consultation with planetary
scientists who actually study planets.)

~~~
scott_s
I'm confused by your parenthetical, as the definition that excludes Pluto (and
Eris) was arrived at by the International Astronomical Union
([https://www.iau.org/](https://www.iau.org/)).

~~~
Robotbeat
IAU is made of astronomers (i.e. People who study stars and stuff), not so
many planetary scientists (who specifically study planets).

~~~
scott_s
I think it's fair to define planets based on an astronomical perspective; it's
clear that Pluto, Eris and things like it, astronomically, belong to a
different class than the other planets. Pluto is now classified as a dwarf
planet. If we didn't "demote" it to a dwarf planet, then we would have to
define a new term for the existing planets.

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sdy
Maybe I missed it in the article, but why would P9 be at a 30 degree angle
from all the other planets. Are they saying that what we know of how solar
systems collapses to the nearly the same plane is wrong?

~~~
Pharylon
It would have been knocked into an eccentric orbit early in the Solar System's
formation (when we had a lot more planets).

It couldn't have formed that far out. We know Uranus and Neptune are too far
away - they formed closer in than they are now, and interactions with Saturn
and Jupiter pushed them out. In fact, there's evidence that they switched
places (Neptune originally being closer). Planet Nine could have been thrown
into an eccentric orbit during this time.

Here's a relevant wikipedia article:
[https://en.wikipedia.org/wiki/Nice_model](https://en.wikipedia.org/wiki/Nice_model)

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fooker
What do you define as a planet though? If you consider our sun a frame of
reference, you might find that technically some far away objects bigger than
the sun have complex periodical movements around the sun.

~~~
devrandomguy
Are you suggesting that the galaxy revolves around the sun? Heresy!

~~~
fooker
I am going to become a flat-galaxier!

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PhasmaFelis
Can we name this one Pluto too, for old times' sake?

~~~
api
I vote for either Yuggoth or Nibiru.

~~~
sohkamyung
Nibiru is usually referred to as "Planet X". If it was called "Planet IX", it
would be a better fit. :-)

~~~
richmarr
IX would be a slightly ominous name to choose :)
[https://en.wikipedia.org/wiki/Ix_(Dune)](https://en.wikipedia.org/wiki/Ix_\(Dune\))

~~~
moomin
There's a remark in one of the books that the Ixians were completely unaware
that their planet was named that because it was the ninth out from the Sun.

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futun
Noob question: Why isn't it passing in front of stars? Are we seeing a
sequential dimming of occluded stars along the plane of the ecliptic?

~~~
foota
My intuition suggests that a planet far out and small would be very difficult
to detect by its occlusion.

This page calculates that Pluto for instance spans only 3 pixels at the Hubble
space telescopes resolution: [http://www.planetary.org/blogs/emily-
lakdawalla/2013/0214101...](http://www.planetary.org/blogs/emily-
lakdawalla/2013/02141014-hubble-galaxy-pluto.html)

~~~
1024core
If Hubble can barely see Pluto, how the heck did terrestrial telescopes find
it in the first place?

~~~
brobinson
Wasn't the presence of a Pluto-like body _known_ because the orbits of other
planets didn't match expectations based on the gravitational pulls of all the
other known bodies in our solar system?

~~~
simias
Not exactly. It's true that Neptune was discovered that way and that people
found Pluto while looking for a "Planet X" that would explain other
gravitational discrepancies:

 _In the 1840s, Urbain Le Verrier used Newtonian mechanics to predict the
position of the then-undiscovered planet Neptune after analyzing perturbations
in the orbit of Uranus. Subsequent observations of Neptune in the late 19th
century led astronomers to speculate that Uranus 's orbit was being disturbed
by another planet besides Neptune._[1]

However it turned out that Pluto was not Planet X after all. After all Neptune
and Uranus are respectively about 7900 and 6700 times more massive than Pluto.

 _In 1978, the discovery of Pluto 's moon Charon allowed the measurement of
Pluto's mass for the first time: roughly 0.2% that of Earth, and far too small
to account for the discrepancies in the orbit of Uranus. Subsequent searches
for an alternative Planet X, notably by Robert Sutton Harrington, failed. In
1992, Myles Standish used data from Voyager 2's flyby of Neptune in 1989,
which had revised the estimates of Neptune's mass downward by 0.5%—an amount
comparable to the mass of Mars—to recalculate its gravitational effect on
Uranus. With the new figures added in, the discrepancies, and with them the
need for a Planet X, vanished. Today, the majority of scientists agree that
Planet X, as Lowell defined it, does not exist. Lowell had made a prediction
of Planet X's orbit and position in 1915 that was fairly close to Pluto's
actual orbit and its position at that time; Ernest W. Brown concluded soon
after Pluto's discovery that this was a coincidence, a view still held
today._[2]

[1]
[https://en.wikipedia.org/wiki/Pluto#Discovery](https://en.wikipedia.org/wiki/Pluto#Discovery)
[2]
[https://en.wikipedia.org/wiki/Pluto#Planet_X_disproved](https://en.wikipedia.org/wiki/Pluto#Planet_X_disproved)

