We may have found the hypothetical Planet 9!
Before the 20th century, we had a pretty good theory that explained a bunch of stuff.
It explained the motion of the planets around the Sun (specifically, it explained
why planets follow an elliptical path). This was the Newton theory. Among other things,
it showed that humans can fly on aeroplanes. It also suggested the idea that an apple and
a feather fall with the same acceleration of 9.81 meters per second squared in the void.
But then, one day, this theory was found to be slightly wrong.
This is because Einstein gave us a better one, which included an extended Newton's theory.
Einstein's gift was amazing. Its theory, the theory of general relativity,
is the best theory of gravitation we have so far.
It fits data, it predicts complex behaviours of celestial objects, and also it is very precise.
For example, when astronomers found that Mercury's orbit was preceding – shortly
meaning that their measurements of Mercury's orbit period were incompatible with Newton's law-
the only possible explanation to that was to add a perturbation. They thought there should have been
something, maybe a planet, perturbing Mercury's orbit employing its gravitational effect.
Astronomers from all over the world were looking for this new possible planet in the Solar System,
and they were calling it “Planet 9”. But no evidence for Planet nine was found.
Instead, it is found that using General relativity instead of Newton's theory,
the mismatched period of Mercury is soon recovered.
They couldn't find any planet nine simply because...there was no planet nine!
As of today, in order to have precise data, we always take into account General Relativity.
And yet something is still unexplained. For example, the orbits of some trans-Neptunian
objects are found to be really weird. Why is that? Scientists think there could be some
possible explanation for that, and some of them have brought to light Planet 9's existence again.
Does planet nine actually exist? Follow me in this video to get to know more about it!
We may have found the first-ever potential candidate for the existence of planet nine,
but we are not so sure about it. It is located of course somewhere
in the Solar System, and if it existed, we would have a new member in the family.
The scientist who claims he may found planet nine is Michael Rowan Robinson,
and he is a really smart astronomer because he decided to take his data from the IRAS survey.
It stands for Infrared Astronomical Satellite (IRAS), and it was a joint project of the US,
UK and the Netherlands. The IRAS mission performed an unbiased, sensitive all-sky survey at 12, 25,
60 and 100 µm, that is, the infrared domain (or in simpler words, the red
part of the electromagnetic spectrum). Although the survey is a very old one,
it is still so precious for astronomers from all over the world, since it is a
source of very important data about distant objects such as galaxies and distant stars.
IRAS increased the number of catalogued astronomical sources by about 70%,
detecting about 350,000 infrared sources. IRAS discoveries also included a disk of dust grains
around the star Vega, six new comets, and very strong infrared emission from interacting galaxies
as well as wisps of warm dust called infrared cirrus which could be found in almost every
direction of space. IRAS also revealed for the first time the core of our galaxy, the Milky Way.
Among the confirmed results, the discovery of a ring of cosmic
dust that surrounds the Solar System at a distance of about 15 billion kilometres.
Subsequent observation of the sky made it possible to search for moving objects.
Jack Meadows and colleagues have thus discovered three asteroids,
comets and in particular a large dust tail associated with Comet Tempel-2.
Now. Why did Robinson choose to look for evidence of planet nine in the IRAS data?
The answer is: because he is a smart guy. But let me explain to you better.
A few years ago, several scientists started to
discover the distant objects that we often refer to as Trans Neptunian objects, TNOS.
Maybe you've already heard of them. Eris, Haumea Sedna are just three of them.
The interesting thing is that a few of them seem to have possessed very unusual orbits,
with specific inclinations and peculiar behaviours. It is like something is pulling
at them, exerting a force on them from a distant region in the solar system.
That's why scientists started to think again about the possibility of a ninth hidden planet,
a hidden object that is not that big, and it is probably located at a long distance,
such that it creates visible effects on this transneptunian objects orbits.
However, this hypothesis was still not a good one since only a few of them were showing strange
behaviours. But in the last six or seven years, a lot more of these TNOS have been discovered, and
some of their orbits did not actually truly match anything of what we were expecting.
Some alternative explanations for the existence of planet nine
have been proposed, and we also talked about them in a previous video, You can check it out here!
https://www.youtube.com/watch?v=9aMWsr1oOM0&t=62s
Shortly, some scientists thought that maybe we are just biased when we're looking for these objects
and where exactly we're finding them. In other words, the existence of planet nine started to be
kind of questioned and the scientific community was still quite divided about its existence.
But then, this smart guy came. He was born in 1942,
and he is an astronomer, astrophysicist and Professor of Astrophysics at Imperial
College London. He previously served as head of the astrophysics group until May 2007
and from 1981 to 1982, and as Gresham Professor of Astronomy.
Rowan-Robinson was awarded the 2008 Hoyle Medal by the Institute of Physics for his research
in infrared and submillimetre astronomy, and observational cosmology.
He conducted an analysis of data collected by the Infrared astronomical satellite in 1983.
What he found seems to be a trio of point sources that just might be Planet Nine.
He concludes his preprint paper, saying that that is actually fairly unlikely to be a real
detection, but the possibility does mean that it could be used to model where the planet might be
now in order to conduct a more targeted search, in the quest to confirm or rule out its existence.
One of the main issues of the study is that IRAS data are somewhat...obsolete.
IRAS used the very first infrared technologies and so the observations are poor quality ones,
compared to the ones we can access today. In his paper, we can read:
"Given the poor quality of the IRAS detections, at the very limit of the survey, and in a very
difficult part of the sky for far-infrared detections, the probability of the candidate
being real is not overwhelming. However, given the great interest of the Planet 9 hypothesis,
it would be worthwhile to check whether an object with the proposed parameters
and in the region of sky proposed, is inconsistent with the planetary ephemerides."
But now the question is: we have a lot of recent surveys which
scanned the night sky. Why did he choose an old and poor quality one?
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Well, he choose to go through IRAS data because it was one of the most important data sources of
the last decades.
First of all, it was the first space telescope to perform a survey of the
entire night sky at infrared wavelengths. But it also discovered some infrared objects
that at first made no sense to anyone. For example, during its operations,
it detected several sources of infrared radiation coming from several stars,
but when the scientists used the Hubble space telescope or a lot of more powerful telescopes,
to see if they could have the same results from those stars, they found nothing.
So initially this was thought to be an IRAS mistake. Maybe something was going wrong with
the telescope. But it turned out that IRAS was actually detecting infrared radiation
coming from protoplanetary disks forming around stars such as Vega.
This was not discovered until 2014, using powerful telescopes (for example Spitzer telescope).
So IRAS was about thirty years ahead, despite its obsolete technologies.
Making some calculations and building up some amazing sets of algorithms, Rowan-Robinson
went through all the IRAS data in order to find the perfect candidate for planet nine,
I bet it was a very hard job, but in the end, he concluded that we may have one.
Of the around 250,000 point sources detected by the satellite, just three are of interest
as a candidate for Planet Nine. In June, July, and September of 1983, the satellite picked out what
appears to be an object moving across the sky. It's not a dead cert, by a long shot. The region
of sky in which the source appears is at low galactic latitude (that is,
close to the plane of the galaxy), and strongly affected by galactic cirrus,
filamentary clouds that glow in far-infrared. So the sources may be noise from these clouds.
if we interpret the candidate as real, we can extrapolate some information about Planet Nine.
According to the IRAS data, it would be between three and five times the mass of Earth,
at an orbital distance of around 225 astronomical units.
Dynamical studies are needed to check whether such an object is consistent
with the ephemerides of other Solar System objects and whether this object can account
for the clustering of the orbits of Kuiper belt dwarf planets," Rowan-Robinson writes.
Although its existence has not been proven yet, direct detection of a ninth planet
would be the first discovery of a new planet orbiting the Solar System in two centuries.
But so far, its detection has proven a little tricky.
After the release of the recent paper,
Caltech astronomer Mike Brown, who was behind the 2015 Planet Nine model, took to Twitter to
suggest that this may be a different planet than the one they had initially proposed.
So what's next? As Rowan-Robinson
himself proposed, we need to follow up studies!
This is a preliminary discovery, maybe an amazing one, but very preliminary.
For example, we need to scan that part of the sky with the new powerful telescopes.
We also may need some other evidence for planet nine coming from different studies and authors.
New evidence would be very useful in order to confirm the planet existence or not.
"This video ends here! Thanks for watching everyone! What are your thoughts about planet
9? Do you think we will ever find it? Is there anything more you want to hear? Let us know in
the comments below, be sure to subscribe, and I'll see you next time on the channel!"