New Clues Emerge for the Existence of Planet 9

Artist's impression of Planet Nine, blocking out the Milky Way. The Sun is in the distance, with the orbit of Neptune shown as a ring. Credit: ESO/Tomruen/nagualdesign

Planet 9 cannot hide forever, and new research has narrowed the range of possible locations further! In January of 2016, astronomers Mike Brown and Konstantin Batygin published the first evidence that there might be another planet in our Solar System. Known as “Planet 9” (“Planet X” to some), this hypothetical body was believed to orbit at an extreme distance from our Sun, as evidenced by the orbits of certain extreme Kuiper Belt Objects (eKBOs).

Since that time, multiple studied have been produced that have attempted to place constraints on Planet 9’s location. The latest study once again comes from Brown and Batygin, who conducted an analytical assessment of all the processes that have indicated the presence of Planet 9 so far. Taken together, these indications show that the existence of this body is not only likely, but also essential to the Solar System as we know it.

The study, titled “Dynamical Evolution Induced by Planet Nine“, recently appeared online and has been accepted for publication in The Astronomical Journal. Whereas previous studies have pointed to the behavior of various populations of KBOs as proof of Planet 9, Brown and Batygin sought to provide a coherent theoretical description of the dynamical mechanisms responsible for these effects.

In the end, they concluded that it would be more difficult to imagine a Solar System without a Planet 9 than with one. As Konstantin Batygin explained in a recent NASA press statement:

“There are now five different lines of observational evidence pointing to the existence of Planet Nine. 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.”

In 2016, Brown and Batygin described the first three lines of observational evidence for Planet 9. These include six extreme Kuiper Belt Objects which follow highly elliptical paths around the Sun, which are indicative of an unseen mechanism affecting their orbit. Second is the fact that the orbits of these bodies are all tilted the same way – about 30° “downward” to the plane of the Kuiper Belt.

The third hint came in the form of computer simulations that included Planet 9 as part of the Solar System. Based to these simulations, it was apparent that more objects should be tilted with respect to the Solar plane, on the order of about 90 degrees. Thanks to their research, Brown and Batygin found five such objects that happened to fit this orbital pattern, and suspected that more existed.

Caltech professor Mike Brown and assistant professor Konstanin Batygin have been working together to investigate Planet Nine. Credit: Lance Hayashida/Caltech

Since the publication of the original paper, two more indications have emerged for the existence of Planet 9. Another involved the unexplained orbits of more Kuiper Belt Objects which were found to be orbiting in the opposite direction from everything else in the Solar System. This was a telltale indication that a relatively close body with a powerful gravitational force was affecting their orbits.

And then there was the argument presented in a second paper by the team – which was led by Elizabeth Bailey, Batygin’s graduate student. This study argued that Planet 9 was responsible for tilting the orbits of the Solar planets over the past 4.5 billion years. This not only provided additional evidence for Planet 9, but also answered a long standing mystery in astrophysics – why the planets are tilted 6 degrees relative to the Sun’s equator.

As Batygin indicated, all of this adds up to a solid case for the existence of a yet-to-discovered massive planet in the outer Solar System:

“No other model can explain the weirdness of these high-inclination orbits. 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.”

A predicted consequence of Planet Nine is that a second set of confined objects (represented in blue) should also exist. Credit: Caltech/R. Hurt (IPAC)

Recent studies have also shed some light on how and where Planet 9 originated. Whereas some suggested that the planet moved to the edge of the Solar System after forming closer to the Sun, others have suggested that it might be an exoplanet that was captured early in the Solar System’s history. At present, the favored theory appears to be that it formed closer to the Sun and migrated outward over time.

Granted, there is not yet a scientific consensus when it comes to Planet 9 and other astronomers have offered other possible explanations for the evidence cited by Batygin and Brown. For instance, a recent analysis based on the Outer Solar System Origins Survey – which discovered more than 800 new Trans-Neptunian Objects (TNOs) – suggests that the evidence could also be consistent with a random distribution of such objects.

In the meantime, all that remains is to find direct evidence of the planet. At present, Batygin and Brown are attempting to do just that, using the Subaru Telescope at the Mauna Kea Observatory in Hawaii. The detection of this planet will not only settle the matter of whether or not it even exists, it will also help resolve a mystery that emerged in recent years thanks to the discovery of thousands of extra-solar planets.

In short, thanks to the discovery of 3,529 confirmed exoplanets in 2,633 solar systems, astronomers have noticed that statistically, the most likely types of planets are “Super-Earths” and “mini-Neptunes” – i.e. planets that are more massive than Earth but not more than about 10 Earth masses. If Planet 9 is confirmed to exist, which is estimated to have 10 times the Mass of Earth, then it could explain this discrepancy.

Planet 9, we know you’re out there and we will find you! Unless you’re not, in which case, disregard this message!

Further Reads: NASA

New Study Indicates that Planet 9 Likely Formed in the Solar System

Artist's impression of Planet Nine, blocking out the Milky Way. The Sun is in the distance, with the orbit of Neptune shown as a ring. Credit: ESO/Tomruen/nagualdesign

In January of 2016, astronomers Mike Brown and Konstantin Batygin published the first evidence that there might be another planet in our Solar System. Known as “Planet 9”, this hypothetical body was believed to orbit at an extreme distance from our Sun. Since that time, multiple studies have been produced that have had tried to address the all-important question of where Planet 9 could have come from.

Whereas some studies have suggested that the planet moved to the edge of the Solar System after forming closer to the Sun, others have suggested that it might be an exoplanet that was captured early in the Solar System’s history. A recent study by a team of astronomers has cast doubt on this latter possibility, however, and indicates that Planet 9 likely formed closer to the Sun and migrated outward during its history.

Their study, titled “Was Planet 9 Captured in the Sun’s Natal Star-Forming Region?“, recently appeared in the Monthly Notices of the Royal Astronomical Society. The team was led by Dr. Richard Parker from the University of Sheffield’s Department of Physics and Astronomy, with colleagues from ETH Zurich. Together, they conducted simulations that cast doubt on the “capture” scenario.

The six most distant known objects in the solar system with orbits exclusively beyond Neptune (magenta) all mysteriously line up in a single direction. Credit: Caltech/R. Hurt (IPAC); [Diagram created using WorldWide Telescope.]
The existence of Planet 9 (or Planet X, for those who maintain that Pluto is still a planet) was first suggested in 2014 by astronomers Chad Trujillo and Scott S. Sheppard, based on the unusual behavior of certain populations of extreme Trans-Neptunian Objects (eTNOs). From a number of studies that took place over the next few years, constraints were gradually placed on the basic parameters of this planet.

Essentially, Planet 9 is believed to be at least ten times as massive as Earth and two to four times the size. It also believed to have a highly elliptical orbit around the Sun, at an average distance (semi-major axis) of approximately 700 AU and ranging from about 200 AU at perihelion to 1200 AU at aphelion. Last, but not least, scientists have estimated that Planet 9 takes between 10,000 and 20,000 years to complete a single orbit of the Sun.

Because of this, it appears unlikely that Planet 9 could have formed in its current location. Hence why astronomers have argued that it either formed closer to the Sun or was captured from another star system billions of years ago. As Dr. Parker explained in University of Sheffield press statement:

“We know that planetary systems form at the same time as stars, and when stars are very young they are usually found in groups where interactions between stellar siblings are common. Therefore, the environment where stars form directly affects planetary systems like our own, and is usually so densely populated that stars can capture other stars or planets.”

Animated diagram showing the spacing of the Solar Systems planet’s, the unusually closely spaced orbits of six of the most distant KBOs, and the possible “Planet 9”. Credit: Caltech/nagualdesign

For the sake of their study, the team conducted simulations of the Solar System when it was still in its “nursery” phase – i.e. in the early process of formation. While interactions with other star systems (and their planets) are known to be common in this period, the team found that even where conditions were optimized for the sake of capturing free-floating planets, the odds of Planet 9 being captured were quite low.

Overall, their simulations indicated that with an orbit like that of Planet 9, only 5 to 10 planets out of 10,000 would be captured when the Solar System was still young. In short, the likelihood that Planet 9 could have been booted out of another star system and captured by our Sun was a paltry 1 out of a 1,000 to 2,000. Not exactly betting odds! As Dr. Parker summarized:

“In this work, we have shown that – although capture is common – ensnaring planets onto the postulated orbit of Planet 9 is very improbable. We’re not ruling out the idea of Planet 9, but instead we’re saying that it must have formed around the sun, rather than captured from another planetary system.”

If Planet 9 was not captured, then there remains only one possibility: ut formed closer to our Sun and gradually migrated beyond the orbit of Neptune, reaching distances occupied only by the most extreme Kuiper Belt Objects. And while the hunt of this elusive and mysterious planet is ongoing, any research which places additional constraints on its characteristics and origin are extremely useful.

By ruling out different scenarios in which the planet formed, researchers are also raising new questions about the history and evolution of our Solar System. From when did all the planets we know come from? Did they form in their current orbits, or did migration play a role? These and other questions are sure to be raised and addressed as we close in on Planet 9.

Further Reading: University of Sheffield, MNRAS

Evidence Mounts for the Existence of Planet Nine

Artist's impression of Planet Nine, blocking out the Milky Way. The Sun is in the distance, with the orbit of Neptune shown as a ring. Credit: ESO/Tomruen/nagualdesign

In January of 2016, astronomers Mike Brown and Konstantin Batygin published the first evidence that there might be another planet in our Solar System. Known as “Planet 9”, this hypothetical body was estimated to be about 10 times as massive as Earth and to orbit that our Sun at an average distance of 700 AU. Since that time, multiple studies have been produced that either support or cast doubt on the existence of Planet 9.

While some argue that the orbits of certain Trans-Neptunian Objects (TNOs) are proof of Planet 9, others argue that these studies suffer from an observational bias. The latest study, which comes from a pair of astronomers from the Complutense University of Madrid (UCM), offers a fresh perspective that could settle the debate. Using a new technique that focuses on extreme TNOs (ETNOs), they believe the case for Planet 9 can be made.

Extreme Trans-Neptunian Objects are those that orbit our Sun at average distances greater than 150 AU, and therefore never cross Neptune’s orbit. As the UMC team indicate in their study, which was recently published in the Monthly Notices of the Royal Astronomical Society, the distances between the ETNOs nodes and the Sun may point the way towards Planet 9.

Artist’s impression of what the theoretical Planet 9 could look like. Credit: NASA

These nodes are the two points at which the orbit of a celestial body crosses the plane of the Solar System. It is at these points that the chances of interacting with other bodies in the Solar System is the greatest, and hence where ETNOs are most likely to experience a drastic change in their orbits (or a collision). By measuring where these nodes are, the team believed they could tell if the ETNOs are being perturbed by another object in the area.

As Carlos de la Fuente Marcos, one of the authors on the study, explained in an interview with The Information and Scientific News Service (SINC):

“If there is nothing to perturb them, the nodes of these extreme trans-Neptunian objects should be uniformly distributed, as there is nothing for them to avoid, but if there are one or more perturbers, two situations may arise. One possibility is that the ETNOs are stable, and in this case they would tend to have their nodes away from the path of possible perturbers, he adds, but if they are unstable they would behave as the comets that interact with Jupiter do, that is tending to have one of the nodes close to the orbit of the hypothetical perturber”.

For the sake of their research, Doctors Carlos and Raul de la Fuente Marcos conducted calculations and data mining to analyze the nodes of 28 ETNOs and 24 extreme Centaurs (which also orbit the Sun at average distances of more than 150 AUs). What they noticed was that these two populations became clustered at certain distances from the Sun, and also noted a correlation between the positions of the nodes and the inclination of the objects.

Animated diagram showing the spacing of the Solar Systems planet’s, the unusually closely spaced orbits of six of the most distant KBOs, and the possible “Planet 9”. Credit: Caltech/nagualdesign

This latter find was especially unexpected, and led them to conclude that the orbits of these populations were being affected by the presence of another body – much in the same way that the orbits of comets within our Solar System have been found to be affected by the way they interact with Jupiter. As De la Fuente Marcos emphasized:

“Assuming that the ETNOs are dynamically similar to the comets that interact with Jupiter, we interpret these results as signs of the presence of a planet that is actively interacting with them in a range of distances from 300 to 400 AU. We believe that what we are seeing here cannot be attributed to the presence of observational bias”.

As already mentioned, previous studies that have challenged the existence of Planet 9 cited how the study of TNOs have suffered from an observational bias. Basically, they have claimed that these studies made systematic errors in how they calculated the orientations in the orbits of TNOs, in large part because they had all been directed towards the same region of the sky.

By looking at the nodal distances of ETNOs, which depend on the size and shape of their orbits, this most recent study offers the first evidence of Planet 9’s existence that is relatively free of this bias. At the moment, only 28 ETNOs are known, but the authors are confident that the discovery of more – and the analysis of their nodes – will confirm their observations and place further constraints on the orbit of Planet 9.

A planetary mass object the size of Mars would be sufficient to produce the observed perturbations in the distant Kuiper Belt. Credit: Heather Roper/LPL

In addition, the pair of astronomers offered some thoughts on recent work that has suggested the possible existence of a Planet 10. While their study does not take into account the existence of a Mars-sized body – which is said to be responsible for an observable “warp” in the Kuiper Belt – they acknowledge that there is compelling evidence that such a planet-sized body exists. As de la Fuente Marcos said:

“Given the current definition of planet, this other mysterious object may not be a true planet, even if it has a size similar to that of the Earth, as it could be surrounded by huge asteroids or dwarf planets. In any case, we are convinced that Volk and Malhotra’s work has found solid evidence of the presence of a massive body beyond the so-called Kuiper Cliff, the furthest point of the trans-Neptunian belt, at some 50 AU from the Sun, and we hope to be able to present soon a new work which also supports its existence”.

It seems that the outer Solar System is getting more crowded with every passing year. And these planets, if and when they are confirmed, are likely to trigger another debate about which Solar bodies are rightly designated as planets and which ones aren’t. If you thought the “planetary debate” was controversial and divisive before, I recommend staying away from astronomy forums in the coming years!

Further Reading: SINC. MNRAS

What Caused the Kuiper Belt to Get Warped?

Astronomers have known about the Kuiper Belt for decades, and were postulating about its existence long before it was even observed. Since that time, many discoveries have been made in this region of space – ranging from numerous minor planets to the fact that the orbital planes of Kuiper Belt Objects (KBOs) are widely dispersed – that have led to new theoretical models of the formation and evolution of the Solar System.

For instance, while conducting measurements of the mean plane of minor planets and KBOs, a team from the Lunar and Planetary Laboratory (LPL) at The University of Arizona discovered a warp in orbits of certain, highly-distant KBOs.  According to their study, this warp could be an indication of a planetary-mass object in the area, one which orbits our Sun even closer than the theoretical “Planet 9“.

The study – “The Curiously Warped Mean Plane of the Kuiper Belt” which is scheduled to be published in the Astronomical Journal – was produced by Kathryn Volk and Renu Malhotra (two astronomers with the LPL). As they stated in their study, the presence of this planet was confirmed by examining the orbits of icy bodies in the very outer reaches of the Solar System.

Artist’s impression of the yet-to-be-discovered “planetary mass object”, who’s existence has been theorized based on the orbital plane of distant Kuiper Belt objects. Credit: Heather Roper/LPL

Whereas most KBOs – which are leftover material from the formation of the Solar System – orbit the Sun close to the mean plane of the Solar System itself, the most distant objects do not. To determine why, the researchers analyzed the tilt angles of the orbital planes of more than 600 KBOs to determine the direction of their precession – i.e. the direction in which these rotating objects experience a change in their orientation.

As Malhotra – a Louise Foucar Marshall Science Research Professor and Regents’ Professor of Planetary Sciences at LPL – illustrated, KBOs operate in a way that is analogous to spinning tops:

“Imagine you have lots and lots of fast-spinning tops, and you give each one a slight nudge. If you then take a snapshot of them, you will find that their spin axes will be at different orientations, but on average, they will be pointing to the local gravitational field of Earth… We expect each of the KBOs’ orbital tilt angle to be at a different orientation, but on average, they will be pointing perpendicular to the plane determined by the Sun and the big planets.”

What they found was that the average plane of these objects was tilted away from the solar plane by about eight degrees, which suggests that a powerful gravitational force in the outer Solar System is tugging on them. “The most likely explanation for our results is that there is some unseen mass,” said Volk in UA News press release. “According to our calculations, something as massive as Mars would be needed to cause the warp that we measured.”

Animated diagram showing the spacing of the Solar Systems planet’s, the unusually closely spaced orbits of six of the most distant KBOs, and the possible “Planet 9”. Credit: Caltech/nagualdesign

According to their calculations, this Mars-size body would likely orbit the Sun at a distance of roughly 60 AU, and with an orbital inclination that was tilted eight degrees to the average plane of the known planets (i.e. the same tilt as the “warped” KBOs). Within these parameters, a planet of this size would have sufficient gravitational influence to warp the orbital plane of the distant KBOs to within 10 AU on either side of it.

In other words, a Mars-sized planet in the outer Kuiper Belt would be able to influence the orbital inclination of KBOs that are between 50 and 70 AUs from the Sun. This is certainly consistent with what we know about the Kuiper Belt, who’s orbital inclination appears to be consistently flat (i.e. consistent with the rest of the Solar System) past a distance of about 50 AU – but changes between a distance of 50 and 80 AU.

As Volk indicated, there is a possibility that this warping could be the result of a statistical fluke. But in the end, their calculations indicated that this is highly unlikely, and that the behavior of distant KBOs is consistent with the existence of a as-yet-unseen gravitational influence:

“But going further out from 50 to 80 AU, we found that the average plane actually warps away from the invariable plane. There is a range of uncertainties for the measured warp, but there is not more than 1 or 2 percent chance that this warp is merely a statistical fluke of the limited observational sample of KBOs… The observed distant KBOs are concentrated in a ring about 30 AU wide and would feel the gravity of such a planetary mass object over time, so hypothesizing one planetary mass to cause the observed warp is not unreasonable across that distance.”  

Artist's impression of Planet Nine, blocking out the Milky Way. The Sun is in the distance, with the orbit of Neptune shown as a ring. Credit: ESO/Tomruen/nagualdesign
Artist’s impression of Planet Nine, blocking out the Milky Way. The Sun is in the distance, with the orbit of Neptune shown as a ring. Credit: ESO/Tomruen/nagualdesign

Another possibility is that another object entirely could have disturbed the plane of the outer Kuiper Belt – for instance, a star passing through the outer Solar System. But as Malhotra explained, this explanation is also a highly unlikely, as any disturbance caused by a passing star would only be temporary and would have manifested itself differently.

“A passing star would draw all the ‘spinning tops’ in one direction,” he said. “Once the star is gone, all the KBOs will go back to precessing around their previous plane. That would have required an extremely close passage at about 100 AU, and the warp would be erased within 10 million years, so we don’t consider this a likely scenario.”

Moreover, the tilt of these objects could not be attributed to the existence of Planet 9, who’s existence has also been suggested based on the extreme eccentricity of certain populations of KBOs. Compared to this Mars-sized planet that is thought to orbit at 60 AUs from the Sun, Planet 9 is predicted to be much more massive (at around 10 Earth masses) and is believed to orbit at a distance of 500 to 700 AU.

Naturally, one has to ask why this planetary-mass body has not been found yet. According to Volk and Malhotra, the reason has to do with the fact that astronomers have not yet searched the entire sky for distant for Solar System objects. Beyond that, there’s also the likely position of the object (within the galactic plane), which is so densely packed with stars that surveys would have a hard time spotting it.

However, with the construction of instruments like the Large Synoptic Survey Telescope (LSST) in Chile nearly complete, opportunities to spot it may be coming sooner other than later. This wide-field survey reflecting telescope, which is run by a consortium that includes the University of Arizona, is expected to provide some of the deepest and widest views of the Universe to date (which will begin in 2020).

In the meantime, and in response to any possible controversies regarding the so-called “Planet Debate”, it is worth noting that this body (if it exists) is currently being referred to as “planetary-mass object”. This is because, by definition, a body needs to have cleared its orbit in order to be called a planet. What’s more, the study does not rule out the possibility that the warp could be the result of more than one planetary mass object in the area.

Therefore, it would premature to state that astronomers – having not yet even confirmed the existence of Planet 9 – are now talking about the existence of a possible “Planet 10”. In the coming years, more news and information will become available, which will hopefully help us put the debate to rest and agree on just how many planets there are out there!

Further Reading: UA News, Earth and Planetary Astrophysics

An Astronomical Detective Tale and the Moon of 2007 OR10

2007 OR10 Moon
2007 OR10 Moon
These two images reveal a moon orbiting the dwarf planet
2007 OR10. NASA/Hubble/ESA/STScI

It isn’t every day we get a new moon added to the list of solar system satellites. The combined observational power of three observatories — Kepler, Herschel and Hubble — led an astronomical detective tale to its climatic conclusion: distant Kuiper Belt Object 2007 OR10 has a tiny moon.

The dwarf planet itself is an enigma wrapped in a mystery: with a long orbit taking it out to a distant aphelion 101 astronomical units (AU) from the Sun, back into the environs of Neptune and Pluto for a perihelion 33 AU from the Sun once every 549 years, 2007 OR10 was discovered by Caltech astronomers Megan Schwamb and Mike Brown in 2007. Nicknamed “Snow White” by Mike Brown for its presumed high albedo, 2007 OR10 was 85 AU distant in the constellation Aquarius at the time of discovery and outbound towards aphelion in 2135. 2007 OR10 is about 1,500 kilometers in diameter, the third largest body known beyond Neptune in our solar system next to Pluto and Eris (nee Xena).

2007 OR10 moon
See the moon (circled?) at +21st magnitude, it’s a tough catch! NASA/Hubble/STScI

Enter the Kepler Space Telescope, which imaged 2007 OR10 crossing the constellation Aquarius as part of its extended K2 exoplanet survey along the ecliptic plane. Though Kepler looks for transiting exoplanets — worlds around other stars that betray their presence by tiny dips in the brightness of their host as they pass along our line of sight — it also picks up lots of other things that flicker, including variable stars and distant Kuiper Belt Objects. But the slow 45 hour rotational period of 2007 OR10 noted by Kepler immediately grabbed astronomers interest: could an unseen moon be lurking nearby, dragging on the KBO like a car brake?

“Typical rotation periods for Kuiper Belt Objects are under 24 hours,” says Csaba Kiss (Konkoly Observatory) in a recent press release. “We looked in the Hubble archive because the slower rotation period could have been caused by the gravitational tug of a moon.”

And sure enough, digging back through archival data from the Hubble Space Telescope taken during a survey of KBOs, astronomers turned up two images of the faint moon from 2009 and 2010. Infrared observations of 2007 OR10 and its moon by the European Space Agency’s Herschel Space Telescope cinched the discovery, and noted an albedo of 19% (similar to wet sand) for 2007 OR10, much darker than expected. The moon is about 200 miles (320 kilometers) in diameter, in a roughly 9,300 mile (15,000 kilometer) orbit.

The discovery was announced at an AAS meeting just last year, and even now, we’re still puzzling out what little we know about these distant worlds. Just what 2007 OR10 and its moon looks like is any guess. New Horizons gave us our first look at Pluto and Charon two short summers ago in 2015, and will give us a fleeting glimpse of 2014 MU69 on New Year’s Day 2019. All of these objects beg for proper names, especially pre-2019 New Horizons flyby.

This also comes on the heels of two new moons for Jupiter, recently announced last month S/2017 J1 and J2.

What would the skies from the tiny moon look like? Well, ancient 2007 OR10 must loom large in its sky, though Sol would only shine as a bright -15th magnitude star, (a little brighter than a Full Moon) its illumination dimmed down to 1/7,000th the brightness enjoyed here on sunny Earth, which would be lost in its glare.

2007 Or10 in the sky
The current position of 2007 OR10 in the night sky. Stellarium

And looking at the strange elliptical orbits of these outer worldlets, we can only surmise that something else must be out there. Will the discovery of Planet 9 be made before the close of the decade?

One thing’s for sure: this isn’t your parent’s tidy solar system with “Excellent Mothers” serving “Nine Pizzas.”

Four Candidates For Planet 9 Located

A concentrated three-day search for a mysterious, unseen planet in the far reaches of our own solar system has yielded four possible candidates. The search for the so-called Planet 9 was part of a real-time search with a Zooniverse citizen science project, in coordination with the BBC’s Stargazing Live broadcast from the Australian National University’s Siding Spring Observatory.

A view of data from SAMI, a new multi-object integral field spectrograph at Siding Spring Observatory, which was used to look for the hypothetical Planet 9. Credit: Dilyar Barat via Twitter.

Researcher Brad Tucker from ANU, who led the effort, said about 60,000 people from around the world classified over four million objects during the three days, using data from the SkyMapper telescope at Siding Spring. He and his team said that even if none of the four candidates turn out to be the hypothetical Planet 9, the effort was scientifically valuable, helping to verify their search methods as exceptionally viable.

“We’ve detected minor planets Chiron and Comacina, which demonstrates the approach we’re taking could find Planet 9 if it’s there,” Tucker said. “We’ve managed to rule out a planet about the size of Neptune being in about 90 per cent of the southern sky out to a depth of about 350 times the distance the Earth is from the Sun.

Researchers from Australian National University pose with BBC astronomers Chris Lintott, Brian Cox and Dara O’Brien. Credit: ANU.

Last year, Caltech astronomers Mike Brown and Konstantin Batygin found indirect evidence for the existence of a large planet when they found that the orbits of several different Kuiper Belt Objects were likely being influenced by a massive body, located 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 the search is difficult because the object is likely 1000 times fainter than Pluto.

The search has been on, with many researchers working on both new observations and sifting through old data. This recent project used archival data from the Skymapper Telescope.

“With the help of tens of thousands of dedicated volunteers sifting through hundreds of thousands of images taken by SkyMapper,” Tucker said, “we have achieved four years of scientific analysis in under three days. One of those volunteers, Toby Roberts, has made 12,000 classifications.”

Mike Brown chimed in on Twitter that he thought this concentrated search was a great idea:

Tucker said he and his team at ANU will work to confirm whether or not the unknown space objects are Planet 9 by using telescopes at Siding Spring and around the world, and he encouraged people to continue to hunt for Planet 9 through Zooniverse project, Backyard Worlds: Planet 9.

Source: ANU

Planet 9 Can’t Run Forever. Two Asteroids Give Up Some Clues

Last year, Caltech astronomers Mike Brown and Konstantin Batygin found indirect evidence for the existence of a large planet in the outer reaches of our Solar System — likely located out past Pluto — and since then, the search has been on. The latest research continues to show signs of an unseen planet, the hypothetical Planet 9.

Astronomers using the Gran Telescopio CANARIAS (GTC) in the Canary Islands looked at two distant asteroids called Extreme Trans Neptunian Objects’ (ETNOs), and spectroscopic observations show and their present-day orbits could be the result of a past interaction with a large “superearth”-type object orbiting the Sun at a distance between 300 to 600 AU.

Researchers say the orbits of asteroids 2004 VN112 and 2013 RF98 suggest that the two were once a binary asteroid which separated after an encounter a large body, with a mass of between 10 and 20 Earth masses.

“The similar spectral gradients observed for the pair 2004 VN112 – 2013 RF98 suggests a common physical origin,” said Julia de León, the first author of a new paper, and who is an astrophysicist at the Instituto de Astrofísica de Canarias (IAC). “We are proposing the possibility that they were previously a binary asteroid which became unbound during an encounter with a more massive object.”

Sequence of images taken with the Gran Telescopio CANARIAS (GTC) to identify one of the ETNO´s studied in this article, 2013 RF98, where one can see how it moves during four consecutive nights. Below, right, visible spectra obtained with the GTC of the two objects 2004 VN112 and 2013 RF98. The red lines show the gradients of the spectra. Credit: Julia de León (IAC).

To test their hypothesis, the team performed thousands of simulations to see how the poles of the orbits would separate as time went on. The results of these simulations suggest that a possible Planet 9 could have separated the pair of asteroids around 5 to 10 million years ago.

de León said this could explain, in principle, how these two asteroids, starting as a pair orbiting one another, became gradually separated in their orbits after an encounter with a much more massive object at a particular moment in time.

The tale of Planet 9 started in 2014, when astronomers 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 altering orbits of several ETNOs the in Kuiper Belt.

Brown and Batygin were looking to verify or refute the research of Trujillo and Shepard, and they painstakingly analyzed the movement of various KBOs. 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 the bodies were found to be inclined at a plane of about 30-degrees different from almost everything else in the Solar System. Brown said the odds of these orbits all occurring randomly are about 1 in 100.

But calculations revealed the orbits could be influenced by 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.

It hasn’t been found yet, but the hunt is on by large telescopes around the world, and a new citizen science project allows people around the world to join in the search.

The latest findings of by de León and team could help point the way to where Planet 9 might be lurking.

Source: PhysOrg

Will You Be The Discoverer Of Planet 9?

Citizen science projects are a great way for anyone to be involved in the scientific process. Average, everyday folks have discovered things like supernovae, previously unseen craters on the Moon and Mars and even new planets orbiting a distant star.

Now, you could be part of one of the most exciting quests yet: finding a mysterious, unseen planet in the far reaches of our own solar system. Last year, Caltech astronomers Mike Brown and Konstantin Batygin found indirect evidence for the existence of a large planet, likely located out past Pluto, and since then, the search has been on. But so far, it has come up empty. And so, astronomers decided they would bring in a little help: You.

“Backyard Worlds: Planet 9 has the potential to unlock once-in-a-century discoveries, and it’s exciting to think they could be spotted first by a citizen scientist,” said UC Berkeley postdoctoral researcher Aaron Meisner, who is helping to head up this latest citizen science project.

A previously cataloged brown dwarf named WISE 0855?0714 shows up as a moving
orange dot (upper left) in this loop of WISE images spanning five years. By viewing
movies like this, anyone can help discover more brown dwarfs or even a 9th planet. Credit: NASA/WISE.

People who sign on to the Backyard World: Planet 9 website will be basically using the same type of technique that was used to find the last planet discovered in our solar system, Pluto. Clyde Tombaugh used a special machine that systematically switched images on glass astronomical plates back and forth, looking for any objects in the night sky that ‘moved’ between the images.

For Backyard Worlds: Planet 9, users will view brief “flipbook” movies made from images captured by NASA’s Wide-field Infrared Survey Explorer (WISE) mission. A faint spot seen moving through background stars might be a new and distant planet in our solar system. Or it could be a nearby brown dwarf star, which would be another exciting discovery.

WISE’s infrared images cover the entire sky about six times over. This has allowed astronomers to search the images for faint, glowing objects that change position over time, which means they are relatively close to Earth. Objects that produce their own faint infrared glow would have to be large, Neptune-size planets or brown dwarfs, which are slightly smaller than stars. WISE images have already turned up hundreds of previously unknown brown dwarfs, including the objects fairly close to us, so astronomers hope that the Backyard Worlds search will turn up a new nearest neighbor to our sun.

NASA wants to bring in all the humans it can for this search, because the human eye is much better than computers at seeing changes between images.

“Automated searches don’t work well in some regions of the sky, like the plane of the Milky Way galaxy, because there are too many stars, which confuses the search algorithm,” said Meisner.

“There are just over four light-years between Neptune, the farthest known planet in our solar system, and Proxima Centauri, the nearest star, and much of this vast territory is unexplored,” said NASA astronomer Marc Kuchner, the lead researcher and an astrophysicist at NASA’s Goddard Space Flight Center. “Because there’s so little sunlight, even large objects in that region barely shine in visible light. But by looking in the infrared, WISE may have imaged objects we otherwise would have missed.”

Check out Backyard Worlds: Planet 9 here, and give Universe Today the scoop when you make your big discovery!

You can find more info in the video below:

Source: UC Berkeley

Evidence Continues To Mount For Ninth Planet

Ever since its existence was first proposed, the evidence for Planet 9 continues to mount. But of course, said evidence has been entirely indirect, consisting mostly of studies that show how the orbits of Trans-Neptunian Objects (TNOs) are consistent with a large object crossing their path. However, evidence is also emerging that comes from the center of the Solar System itself.

This latest line of evidence comes from Caltech, where researchers Elizabeth Bailey, Konstantin Batygin, and Michael E. Brown (the latter of whom were the ones who first proposed Planet 9’s existence) have published a new study linking solar obliquity to the existence of Planet 9. Essentially, they claim that the axial tilt of the Sun (6°) could be due to the gravitational influence a large planet with an extreme orbit.

To recap, the issue of Planet was first raised in 2014 by astronomers Scott Sheppard and Chadwick Trujillo. Noting the similarities in the orbits of distant Trans-Neptunian Objects (TNOs), they postulated that a massive object was likely influencing them. This was followed in 2016 by Konstantin Batygin and Michael E. Brown of Caltech suggesting that an undiscovered planet was the culprit.

The orbits of several KBOs provide indications about the possible existence of Planet 9. Credit: Caltech/R. Hurt (IPAC)
The orbits of several KBOs provide indications about the possible existence of Planet 9. Credit: Caltech/R. Hurt (IPAC)

Calling this body Planet 9, they speculated that it had a mass 10 times greater than that of Earth, and took 20,000 years to complete a single orbit of our Sun. They also speculated that its orbit was tilted relative to the other planets of our Solar System, and extremely eccentric. And little by little, examinations of other Solar bodies have shown that Planet 9 is likely out there.

For the sake of their study – “Solar Obliquity Induced by Planet Nine“, which was recently published in the Astrophysical Journal – the research team (led by Bailey) looked to the obliquity of the Sun. As they state in their paper, the six-degree axial tilt of the Sun can only be explained in one of two ways – either as a result of an asymmetry that was present during the formation of Solar System, or because of an external source of gravity.

To test this hypothesis, Bailey, Batygin and Brown used an analytic model to test how interactions between Planet 9 and the rest of the Solar System would effect their orbits over the course of the last 4.5 billion years. As Elizabeth Bailey, a graduate student at Caltech’s Division of Geological and Planetary Sciences and the lead author on the paper, told Universe Today via email:

“We simulated the solar system’s motion. Planet 9 forces the solar system to slowly wobble. If Planet 9 is out there, we are in the process of wobbling right now, as we speak! But it happens very slowly, a few degrees tilt per billion years. Meanwhile the sun is not wobbling much,  so it looks like the sun is tilted. A range of Planet 9 parameters cause exactly the configuration of the sun that we see today.

Animated diagram showing the spacing of the Solar Systems planet’s, the unusually closely spaced orbits of six of the most distant KBOs, and the possible “Planet 9”. Credit: Caltech/nagualdesign
Animated diagram showing the spacing of the Solar Systems planet’s, the unusually closely spaced orbits of six of the most distant KBOs, and the possible “Planet 9”. Credit: Caltech/nagualdesign

In the end, they concluded that the Sun’s obliquity could only be explained by the influence of giant planet with an extreme orbit, one that is consistent with the characteristics attributed to Planet 9. In other words, the existence of Planet 9 offers an explanation for the Sun’s peculiar behavior, something which has remained a mystery until now.

“Planet Nine was first hypothesized because the orbits of objects in the outer reaches of the solar system are confined in physical space,” said Bailey. “Those orbits would be all over the place unless something is currently stopping them. The only explanation so far is Planet Nine. For over 150 years, people have wondered why the sun is tilted. Personally I’d say that Planet 9 offers the first satisfying explanation. If it exists, it tilted the sun.”

In addition, the subject of Planet 9 was also raised at the joint 48th meeting of the American Astronomical Society’s Division for Planetary Sciences and 11th European Planetary Science Congress, which took place from Oct 16th to 21st in Pasadena, California. During the course of the meeting, researchers from Arizona University shared the results of their own study, which was published back in August.

The Arizona research team was led by Renu Malhotra, a Regents’ Professor of Planetary Sciences in the University of Arizona’s Lunar and Planetary Lab. For the sake of their study, titled “Corralling a Distant Planet with Extreme Resonant Kuiper Belt Objects“, they examined the orbital patterns of four extreme Kuiper Belt Objects (KBOs), which have the longest orbital periods of any known objects.

Artist's impression of the the possible Planet 9 at the edge of the Solar System. Credit: Robin Dienel/Carnegie Science
Artist’s impression of the the possible Planet 9 at the edge of the Solar System. Credit: Robin Dienel/Carnegie Science

According to their calculations, the presence of a massive planet – one that would complete an orbit around the Sun every 17,117 years, and at an average distance (semimajor axis) of 665 AU – would explain the orbital pattern of these four objects. These results were consistent with the estimates concerning the orbital period of Planet 9, its orbital path, and it mass.

“We analyzed the data of these most distant Kuiper Belt objects,” Malhotra said, “and noticed something peculiar, suggesting they were in some kind of resonances with an unseen planet… Our paper provides more specific estimates for the mass and orbit that this planet would have, and, more importantly, constraints on its current position within its orbit.”

Looks like Planet 9’s days of hiding in the outer Solar System may be numbered!

Further Reading: arXiv, Caltech, Europlanet