A ninth
Planet evidenced (but not detected yet) in our Solar System– 2016- Jan 20
Caltech astronomers Michael
Brown and Konstantin Batygin
have discovered, with 90% certainty, evidence of a new planet in our solar
system, whose orbit, elliptical and extremely eccentric, would take her between
10,000 to 20,000 years to turn around our sun—the reason why it has escaped
detection up to now.
They have called it PLANET NINE (since Pluto was demoted as a
planet). It’s a massive planet, with 10 times the mass of Earth (two to four
times the diameter of the Earth), and it orbits 20 times farther from the sun
than Neptune. It would be a giant, rocky, and icy, planet, with an atmosphere
of sorts.
The funny point is that these astronomers were on the look-out to smash
any unorthodox thinking and theory about the famous Planet X (or Tenth Planet).
. . and just found it. The Relativity calculus, they say, brings clear evidence;
they know the orbit path, and the only thing that’s lacking is to detect, with
the most powerful telescopes, where exactly it is on this path. Something they
predict could happen within the next two years.
Read on this detailed article from the Washington Post below, printed
the day their article was published in the Astronomical Journal (active links
below).
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washingtonpost.com/news/speaking-of-science/wp/2016/01/20/
By Joel Achenbach and Rachel Feltman; January 20, 2016
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New evidence suggests a ninth planet lurking at the edge of the solar system
Astronomers at the California Institute of Technology announced
Wednesday that they have found new evidence of a giant icy planet
lurking in the darkness of our solar system far beyond the orbit of Pluto. They
are calling it "Planet Nine."
Their paper, published in the Astronomical Journal, estimates
the planet's mass as five to 10 times that of the Earth. But the authors,
astronomers Michael Brown and Konstantin
Batygin, have not observed the planet directly.
Instead, they have inferred its existence from the motion of
recently discovered dwarf planets and other small objects in the outer solar
system. Those smaller bodies have orbits that appear to be influenced by the
gravity of a hidden planet – a "massive perturber." The
astronomers suggest it might have been flung into deep space long ago
by the gravitational force of Jupiter or Saturn.
Telescopes on at least two continents are searching for the
object, which on average is 20 times farther away than the eighth planet,
Neptune. If "Planet Nine" exists, it's big – about two to four times
the diameter of the Earth, which would make it the fifth-largest planet after
Jupiter, Saturn, Uranus and Neptune. But at such extreme distances, it would
reflect so little sunlight that it could evade even the most powerful
telescopes.
Confirmation of its existence would reconfigure the models of the
solar system. Pluto, discovered in 1930, spent three-quarters of a century as
the iconic ninth planet. Then, a decade ago, Pluto received a controversial
demotion, in large part because of Brown.
His observations of the outer solar system identified many small
worlds there – some close to the size of Pluto – and prompted the International
Astronomical Union to reconsider the definition of a planet. The IAU voted to
change Pluto's classification to "dwarf planet," a decision
mocked repeatedly last summer when NASA's New Horizons probe flew past
Pluto and revealed a world with an atmosphere, weather and a volatile and
dynamically reworked surface.
Brown, who tweets under the handle @plutokiller and who wrote
the book "How I Killed Pluto and Why It Had It Coming," said now
may be the time to rewrite the textbooks yet again.
"My daughter, she's still kind of mad about Pluto being
demoted, even though she was barely born at that time," Brown said.
"She suggested a few years ago that she'd forgive me if I found a new
planet. So I guess I've been working on this for her."
NASA's director of planetary science, Jim Green, cautioned
Wednesday that there could be other explanations for the observed motion of the
small bodies in the outer solar system. He referenced the famous dictum from
Carl Sagan that "extraordinary claims require extraordinary
evidence."
“The Sagan Rule applies. If it's there, find it. I challenge you.
Somebody out there oughta find it," Green said. But he said he was
personally excited about the new research: "What an era we're in, where
we’re discovering new things about our solar system that we never thought
possible even a handful of years ago."
Brown and Batygin initially set out to prove that Planet Nine
didn't exist. Their paper builds on earlier research by two other
astronomers that revealed a peculiar clustering of the small, icy objects
discovered in the past decade or so in the remote regions of the solar system.
In 2014, Scott Sheppard
of the Washington-based Carnegie Institution of Science and Chad Trujillo of the Gemini Observatory
in Hawaii published a paper in the journal Nature that discussed the potential
existence of a giant planet affecting the orbits of those dwarf worlds.
Sheppard and Trujillo noted a similarity in the motion of those bodies when
they are closest to the sun.
"We thought their idea was crazy," Brown said,
explaining that extra planets are always the "go-to suggestion" when
astronomers find orbital behavior they can't explain. But he and Batygin
struggled to debunk that hypothetical ninth planet. They used mathematical
equations and then computer models, ultimately concluding that the best
explanation for the smaller objects' clustering was the gravitational effects
of something far bigger.
Such clustering is similar to what's seen in some asteroids
that are about as close to the sun as the Earth. They wind up in stable orbits
that keep them far from Earth and free from any significant disturbance by the
Earth's gravity.
"Until then, we didn't really believe our results ourselves.
It just didn't make sense to us," Brown said. But their modeling showed
that a planet with 10 times the mass of Earth would exert an influence over the
orbits of the smaller bodies and keep them from coming as close to the sun as
they should. It would also slowly twist these orbits by 90 degrees, making them
periodically perpendicular to the plane of the solar system.
"In the back of my head, I had this nagging memory that
someone had found some of these modulating objects and not known what to
make of them," Brown said. "And sure enough, these objects do
exist. And they were exactly where our theory predicts they should
be." That's when the Caltech researchers started to take Planet Nine
seriously. "That was the real jaw-dropping moment, when it went from a
cute little idea to something that might be for real," he said.
Sheppard, who co-wrote the paper that Brown and Batygin set out to
disprove, says the existence of a hidden planet is still a big unknown.
"Until we actually see it for real, it will always be questionable as to
whether it exists," he said, cautioning that
the latest calculations are based on a relatively small number of
known objects and that further observations and detections of perturbed bodies
would bolster the hypothesis.
Still, Sheppard significantly upped the odds of
discovery – from 40 percent before to 60 percent now. “Some people took it
seriously, but a lot of people didn’t," he said of his own study's
findings. "With this new work, it’s much more rigorous, and people will
take it more seriously now.” Brown said he puts the odds of Planet Nine being
real as "maybe 90 percent."
From the Côte d'Azur Observatory in Nice, France, planetary
scientist Alessandro Morbidelli agreed that the evidence was stronger
this time. "I immediately felt that this paper, for the first time, was
providing convincing evidence for a new planet in the solar system," said
Morbidelli, an expert in these kinds of orbital movements who was not involved
in either study. "I don't see any alternative explanation to that offered
by Batygin and Brown." "We will find it one day," he added.
"The question is when."
The past two decades have seen a burst of discoveries as
astronomers have scrutinized the light of distant stars and looked for signs of
orbiting planets. More than a thousand such planets have been detected through
analysis of starlight that has traveled across the vast interstellar distances.
Brown and Batygin, however, have been searching closer to home, looking for
objects that orbit the sun and remain unseen only because the outer regions of
the solar system are exceedingly dark.
The thought of a hidden planet larger than Earth is intriguing,
but for now it's difficult to say too much about the hypothetical
conditions there. Brown believes it's
probably an icy, rocky world with a small envelope of gas – a planet that
could have been the core of a gas giant had it not been ejected into a wonky,
highly elliptical orbit. It might not make its closest approach of the
sun more than once every 10,000 years, and even then it would remain far
beyond the known planets.
The situation mimics what happened in the 19th century when
careful observation of the seventh planet, Uranus, indicated that there must be
another body in far-distant space influencing its orbit. That
work led eventually to the discovery of Neptune.
It would be difficult to see the ninth planet if it's
not at or near its closest approach to the sun. Brown doesn't believe the
object is at that point, saying it would have been spotted by now. But he
does think that the most powerful telescopes on the planet, if pointed in
precisely the right direction, might be able to detect it even when it is most
distant from the sun. "We've been looking for it for a while now, but the
sky is pretty big," Brown said. "We know its path, but not where it
is on that path."
He and Batygin hope their paper's publication will infuse the
search with new energy. "If other people – better astronomers – get
excited about the idea of finding Planet Nine, we could hopefully see it within
a couple of years," he said. . . . If and when it's spotted, Planet Nine
would be evaluated by the same criteria that got Pluto demoted. Brown isn't
concerned about that. "That's not even a question -- it's definitely a
planet," he said. One of the trickiest criteria for planet status, based on
the standards set by the International Astronomical Union, is that a planet
must "clear the neighborhood" around its orbital zone. It needs to have the gravitational prowess
to change the orbits of other objects.
"Planet Nine is forcing any objects that cross its orbit to
push into these misaligned positions. It fits that concept perfectly,"
Brown said. The "Pluto killer" added: "Not to mention the fact
that it's 5,000 times the mass of Pluto."
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