The super-Earth that came home for dinner

October 5, 2017 by Pat Brennan
An artist's illustration of a possible ninth planet in our solar system, hovering at the edge of our solar system. Neptune's orbit is shown as a bright ring around the Sun. Credit: ESO/Tom Ruen/nagualdesign

It might be lingering bashfully on the icy outer edges of our solar system, hiding in the dark, but subtly pulling strings behind the scenes: stretching out the orbits of distant bodies, perhaps even tilting the entire solar system to one side.

If a planet is there, it's extremely distant and will stay that way (with no chance—in case you're wondering—of ever colliding with Earth, or bringing "days of darkness").It is a possible "Planet Nine"—a world perhaps 10 times the mass of Earth and 20 times farther from the sun than Neptune. The signs so far are indirect, mainly its gravitational footprints, but that adds up to a compelling case nonetheless.

One of its most dedicated trackers, in fact, says it is now harder to imagine our solar system without a Planet Nine than with one.

"There are now five different lines of observational evidence pointing to the existence of Planet Nine," said Konstantin Batygin, a planetary astrophysicist at Caltech in Pasadena, California, whose team may be closing in. "If you were to remove this explanation and imagine Planet Nine does not exist, then you generate more problems than you solve. All of a sudden, you have five different puzzles, and you must come up with five different theories to explain them."

Batygin and his co-author, Caltech astronomer Mike Brown, described the first three breadcrumbs on Planet Nine's trail in a January 2016 paper, published in the Astronomical Journal. Six known objects in the distant Kuiper Belt, a region of icy bodies stretching from Neptune outward toward interstellar space, all have elliptical orbits pointing in the same direction. That would be unlikely—and suspicious—enough. But these orbits also are tilted the same way, about 30 degrees "downward" compared to the pancake-like plane within which the orbit the sun.

Breadcrumb number three: Computer simulations of the solar system with Planet Nine included show there should be more objects tilted with respect to the solar plane. In fact, the tilt would be on the order of 90 degrees, as if the plane of the solar system and these objects formed an "X" when viewed edge-on. Sure enough, Brown realized that five such objects already known to astronomers fill the bill.

Two more clues emerged after the original paper. A second article from the team, this time led by Batygin's graduate student, Elizabeth Bailey, showed that Planet Nine could have tilted the planets of our solar system during the last 4.5 billion years. This could explain a longstanding mystery: Why is the plane in which the planets orbit tilted about 6 degrees compared to the sun's equator?

"Over long periods of time, Planet Nine will make the entire solar-system plane precess or wobble, just like a top on a table," Batygin said.

The last telltale sign of Planet Nine's presence involves the solar system's contrarians: objects from the Kuiper Belt that orbit in the opposite direction from everything else in the solar system. Planet Nine's orbital influence would explain why these bodies from the distant Kuiper Belt end up "polluting" the inner Kuiper Belt.

"No other model can explain the weirdness of these high-inclination orbits," Batygin said. "It turns out that Planet Nine provides a natural avenue for their generation. These things have been twisted out of the solar system plane with help from Planet Nine and then scattered inward by Neptune."

The remaining step is to find Planet Nine itself. Batygin and Brown are using the Subaru Telescope at Mauna Kea Observatory in Hawaii to try to do just that. The instrument is the "best tool" for picking out dim, extremely distant objects lost in huge swaths of sky, Batygin said.

But where did Planet Nine come from? Batygin says he spends little time ruminating on its origin—whether it is a fugitive from our own solar system or, just maybe, a wandering rogue planet captured by the sun's gravity.

"I think Planet Nine's detection will tell us something about its origin," he said.

Other scientists offer a different possible explanation for the Planet Nine evidence cited by Batygin. A recent analysis based on a sky mapping project called the Outer Solar System Origins Survey, which discovered more than 800 new "trans-Neptunian objects," suggests that the evidence also could be consistent with a random distribution of such objects. Still, the analysis, from a team led by Cory Shankman of the University of Victoria, could not rule out Planet Nine.

If Planet Nine is found, it will be a homecoming of sorts, or at least a family reunion. Over the past 20 years, surveys of planets around other stars in our galaxy have found the most common types to be "super Earths" and their somewhat larger cousins—bigger than Earth but smaller than Neptune.

Yet these common, garden-variety planets are conspicuously absent from our solar . Weighing in at roughly 10 times Earth's mass, the proposed Planet Nine would make a good fit.

Planet Nine could turn out to be our missing super Earth.

Explore further: Curious tilt of the sun traced to undiscovered planet

More information: Michael E. Brown et al. OBSERVATIONAL CONSTRAINTS ON THE ORBIT AND LOCATION OF PLANET NINE IN THE OUTER SOLAR SYSTEM, The Astrophysical Journal (2016). DOI: 10.3847/2041-8205/824/2/L23

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ECOnservative
5 / 5 (6) Oct 05, 2017
TNOs with periods greater a few thousand years will be extraordinarily difficult to observe. With a slew of new telescopes coming online in the next few years (JWST, LSST, etc.) with widely varying (but complimentary) abilities we might actually be able to settle this.
rrwillsj
3 / 5 (3) Oct 05, 2017
ECO, think big! The accumulation of verifiable facts over the next few decades will not settle anything.

Bad News...The True Believers will continue to delude themselves that phenomena such as Planet Nine are deliberately directed at them. That the outlier planetesimal is heaven or hell. Depending upon their consumption of anti-depressant medications.

The Good News is that this accumulation of verifiable data will build the opportunity to figure what questions need to be asked next.

maholmes1
2.5 / 5 (4) Oct 05, 2017
"It might be lingering bashfully on the icy outer edges of our solar system..." It might not be real. Let's see some telescopic images.

And it should be Planet X. Not Planet Nine. That's either Neptune or Pluto, depending on whether you accept a simple geophysical definition in which hydrostatic equilibrium and orbiting the Sun independently (or not orbiting any star) is enough, in which case Ceres would be a planet, or if you add a minimum diameter of 2000 kilometers. This object, if it exists, would be Planet 14 and counting.
baudrunner
1 / 5 (5) Oct 05, 2017
Joshua's longest day, in 1448 BCE, was documented and recorded by ancient Chinese, by the ancient Inca before they lost their writing skills, and by two Canadian Ojibway tribes, to our knowledge. Only in the Middle East does this become a religious event, the area which was ground zero for "those who to earth from heaven came", supposedly. The phenomenon is a cosmological one, and is attributed to the close passing of a large planet about four times the size of Earth temporarily affecting the normal motion of the Earth. Documented evidence taken from even more ancient Sumerian clay tablets report that a large planet once passed so close to Mars that most of Mars' surface water and all of its atmosphere was sucked away.

No sunspots were ever reported prior to the early 1600's. Then massive sunspot activity was recorded. Evidence of a planetary collision? Maybe there was a planet X, and we are still witnessing the gravitational effects of its passages?
yaridanjo
1 / 5 (3) Oct 06, 2017
We mixed Blabatsky's theosophhy with IRAS point IRAS 1732+239 and we got a consistent orbital inclination of 48.44 +/- 0.23 degrees agreeing well with the UofAZ anticipated values of 18 or,48 degrees. The probability of fortuitous correlation is 1 chance in 250. Using the 4300 year old Akkadian seal, we found an excellent fit of the mass of our Jovian planets relative to the Sun. It also gave us the mass of this body to ben141 +/- 35 Earth masses, far different than the 10 - 20 Earth masses based on ?????. The semi major axis is 291.2 AU, close to the range the Marcos brothers anticipate. It is not a stolen planet, but rather one in a very stable orbit that would not be ejected by a passing star over the lifetime of the solar system (490 AU). Bing:
VULCAN REVEALED
A Dangerous New Jovian Sized Body In Our Solar System
We found it in 2002.
Da Schneib
5 / 5 (2) Oct 06, 2017
Cool. That's pretty good evidence, if you like William of Ockham's Razor. But I'd still like to see them actually find it and take pictures. Since we keep finding all these super earths, maybe it would be good to have one we can take a look at close up and personal.
barakn
3.7 / 5 (3) Oct 10, 2017
No sunspots were ever reported prior to the early 1600's. Then massive sunspot activity was recorded. Evidence of a planetary collision? Maybe there was a planet X, and we are still witnessing the gravitational effects of its passages?
"Chinese astronomers recorded solar activity around 800 B.C. and astronomers in both China and Korea frequently observed sunspots. ... "In the third year of Lothar, emperor of the Romans, in the twenty-eighth year
of King Henry of the English...on Saturday, 8 December, there appeared from the morning right up to the evening two black spheres against the sun." This description of sunspots, and the earliest known drawing of sunspots, appears in John of Worcester's Chronicle recorded in 1128." http://chandra.ha...cord.pdf
baudrunner
1 / 5 (1) Oct 13, 2017
Chinese astronomers recorded solar activity around 800 B.C.
..doesn't mention sunspots, more likely prominences.
and astronomers in both China and Korea frequently observed sunspots. ...
..reads like author's lead-in to the description of the "spheres".
two black spheres against the sun
..not sunspots, but probably transiting planets Venus and/or Mercury.

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