Dwarf planet Pluto, has it an ocean?

This 24 May 2019 video says about itself:

Pluto might seem like the least likely place to find liquid water, but thanks to New Horizons, we have new information about oceans on the dwarf planet and more from the outer reaches of the solar system!

By Lisa Grossman, 27 March 2020:

If Pluto has a subsurface ocean, it may be old and deep

New research hints that liquid water might be common at the solar system’s edge

A suspected subsurface ocean on Pluto might be old and deep.

New analyses of images from NASA’s New Horizons spacecraft suggest that the dwarf planet has had an underground ocean since shortly after Pluto formed 4.5 billion years ago, and that the ocean may surround and interact with the rocky core.

If so, oceans could be common at the solar system’s edge — and may even be able to support life. That possibly “transforms the way we think about the Kuiper Belt”, the region of icy objects beyond the orbit of Neptune (SN: 3/27/19), says planetary scientist Adeene Denton of Purdue University in West Lafayette, Ind.

On its pass through the Kuiper Belt in 2015, New Horizons revealed that despite the dwarf planet’s location nearly 6 billion kilometers from the sun, Pluto showed signs of hosting an ocean of liquid water beneath an icy shell (SN: 9/23/16).

How much liquid may lie beneath Pluto’s ground, how long it’s been there, and how much the water may have partially frozen over time is hard to tell from the surface. The new research, which had been scheduled for presentation the week of March 16 at the canceled Lunar and Planetary Science Conference in The Woodlands, Texas, has dug into those questions.

“If there’s an ocean today, it raises the question of, when did that ocean get there?” says planetary scientist Carver Bierson of the University of California, Santa Cruz.

Bierson considered two possible histories for Pluto’s potential ocean. If the dwarf planet had a “cold start,” any subsurface water would first have been frozen before melting under heat from decaying radioactive elements in the dwarf planet’s core, only to partially freeze again over time. In that scenario, Bierson expected to see cracks and ripples across Pluto’s icy shell from the orb’s contraction as the ice melted and then expansion as water refroze. Contracting would make the ice crumple into mountainlike features, while expanding would stretch the ice and create faults and graben.

Bierson’s second scenario envisioned a “warm start” for Pluto, where the ocean would have been liquid for nearly all of Pluto’s 4.5-billion-year existence. In that case, the surface would show only cracks from the sea expanding as it partially froze. And that’s exactly what Bierson and colleagues found in New Horizon’s images, suggesting that Pluto’s liquid ocean is nearly as old as the dwarf planet itself.

“That means maybe Pluto did start off warm,” Bierson says. “Maybe it started with a liquid ocean really early on.”

In a separate study, Denton and colleagues considered the impact that formed Sputnik Planitia, the left lobe of Pluto’s distinctive heart-shaped basin. Because of how New Horizons flew past Pluto, scientists’ view of half the dwarf planet is fuzzy. But the team was able to see lines on Pluto’s surface on the exact opposite side of the globe from Sputnik Planitia, the researchers reported in October 2019 at arXiv.org. Those lines might be the imprints of shock waves from a massive impact that formed the enormous basin, Denton says.

“If the impact is large enough … the planet itself can act like a lens, and focus the wave energy at the exact opposite point on the planet from the impact,” she says.

Pluto’s internal structure would have controlled how those shock waves shuddered through the dwarf planet. Looking at the cracks in the surface ice could give clues to the thickness of the proposed ocean or the core’s chemical makeup. So Denton and her colleagues ran computer simulations of an impact to look for clues.

“We got the fun answer,” she says. To explain the lines seen on the dwarf planet, not only would Pluto need a large ocean, 150 kilometers or more in thickness, but the core must contain minerals, such as serpentine, that form through interactions between rock and water. Astrobiologists think that water-rock interactions could provide energy and nutrients for life (SN: 5/19/15). The possibility of a somewhat soggy core could let life get a toehold at the fringes of the solar system, Denton says.

“It’s certainly not exactly a smoking gun,” she says. “But it’s exciting.”

The possibility that Pluto has a habitable ocean raises the odds that other Kuiper Belt objects do too, says planetary scientist James Tuttle Keene of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who is a member of the New Horizons team but was not involved in either study.

“This lays out one of the coolest hypotheses that a future Pluto mission could test,” he says. “If Pluto can have an ocean and potentially be habitable, it’s very likely that other bodies in the Kuiper Belt also are ocean worlds and also are potentially habitable.”

Astronomers have found the edge of the Milky Way at last. Our galaxy spans 1.9 million light-years, a new study finds: here.

Trans-Pluto dwarf planet Ultima Thule, first photos

This 21 June 2019 video is called What Did New Horizons See During Its Journey To Pluto And Beyond? 2006-2019.

A 30 August 2018 video used to say about itself:

NASA’s Pluto probe spots the next deep space rock it’s zooming toward

NASA’s New Horizons spacecraft, known for flying by Pluto in 2015, has finally spotted its next target at the edge of the Solar System. On August 16th, the distant probe captured its first images of the space rock it’s currently zooming toward — an icy body nearly 20 miles across that’s been nicknamed Ultima Thule.

It’s a major milestone for the New Horizons team as they prepare the spacecraft for its rendezvous with Ultima Thule on New Year’s Day 2019.

The New Horizons spacecraft has been en route to Ultima Thule ever since October 2015, just a few months after it flew by Pluto in July.

Following the Pluto meet-up, NASA decided to extend the New Horizons mission so that the vehicle would fly by another target in the distant Solar System. The mission team selected Ultima Thule, also named 2014 MU69, since it’s in an ideal position beyond Pluto, and it didn’t take too much fuel for New Horizons to change course to meet up with the rock.

By Christopher Crockett, 2:39pm, August 29, 2018:

New Horizons has sent back the first images of Ultima Thule, its next target

New Horizons has its next destination in sight.

The spacecraft, which buzzed Pluto in 2015, captured its first images on August 16 of the remote icy world nicknamed Ultima Thule, confirming that New Horizons is on track for its January 1 flyby. With about 160 million kilometers to go — roughly the same distance as Earth is from the sun — the tiny world appears as no more than a faint speck in the probe’s camera.

The pictures also barely set a new record: At roughly 6 billion kilometers from Earth, they are the farthest images ever taken. For decades, that honor was held by the Voyager 1 spacecraft, which in 1990 snapped pictures of Earth and many of our neighboring planets from nearly the same distance.

Officially dubbed 2014 MU69, Ultima Thule is part of the Kuiper Belt, a field of frozen detritus left over from the formation of the planets 4.6 billion years ago. By sending New Horizons to take pictures and measure the chemical makeup of Ultima’s surface, researchers hope to unearth clues about the origin of our solar system.

Celebrities’ names now on Pluto’s moon Charon

The International Astronomical Union selected for features on Pluto's moon Charon these 12 names out of a pool of selections that included characters from Lord of the Rings and Marvel comics

The International Astronomical Union selected for features on Pluto’s moon Charon these 12 names out of a pool of selections that included characters from Lord of the Rings and Marvel comics.

By Dan Garisto, 7:00am, April 20, 2018:

Celebrity names now mark places on Pluto’s moon Charon

Somewhere on the distant moon is a mountain with Stanley Kubrick’s name on it

Pluto’s largest moon, long seen as mysterious smudge at the outer reaches of our solar system, was revealed in 2015 closeup images to be pocked with craters, mountains and steep-sided depressions called chasmas. Now, 12 of those topographical features have names.

Charon’s six most prominent craters were named for fictional explorers, including Dorothy who visited the fantastical land of Oz, time traveler Revati from the ancient Indian epic Mahabharata, and Nemo for the captain of the ship Nautilus in Twenty Thousand Leagues Under the Sea.

Three chasmas received nautically themed names — Argo for the Greek ship sailed by Jason to retrieve the Golden Fleece, Caleuche for the mythological ghost ship said to travel off the Chilean coast, and Manjet for one of Egyptian sun god Ra’s vessels. The names for Charon’s mountains honor three real-life luminaries: film director Stanley Kubrick and science fiction writers Octavia E. Butler and Sir Arthur C. Clarke.

Before the International Astronomical Union announced the names April 11, scientists referred to Charon’s features with nicknames like “brown mountain” or “yellow mountain,” says Rita Schulz, a planetary scientist who heads the union’s Working Group for Planetary System Nomenclature. In contrast, the new names have an appeal that “engages [the] public in science”, she says. And that, she adds, “is quite good.”

First global maps of Pluto and Charon show the worlds’ highs and lows. Made with New Horizons’ data, the charts reveal never-before-seen details. By Lisa Grossman, 4:50pm, July 13, 2018.

Dwarf planet Pluto features get official names

Pluto features named

From the International Astronomical Union:

7 September 2017

Pluto Features Given First Official Names

The Working Group for Planetary System Nomenclature (WGPSN) of the International Astronomical Union (IAU) has officially approved the naming of fourteen features on the surface of Pluto. These are the first geological features on the dwarf planet to be named following the close flyby by the New Horizons spacecraft in July 2015.

The IAU has assigned names to fourteen geological features on the surface of Pluto. The names pay homage to the underworld mythology, pioneering space missions, historic pioneers who crossed new horizons in exploration, and scientists and engineers associated with Pluto and the Kuiper Belt. This is the first set of official names of surface features on Pluto to be approved by the IAU, the internationally recognised authority for naming celestial bodies and their surface features.

NASA’s New Horizons team proposed the names to the IAU following the first reconnaissance of Pluto and its moons by the New Horizons spacecraft. Some of the names were suggested by members of the public during the Our Pluto campaign, which was launched as a partnership between the IAU, the New Horizons project and the SETI Institute. Other names had been used informally by the New Horizons science team to describe the many regions, mountain ranges, plains, valleys and craters discovered during the first close-up look at the surfaces of Pluto and its largest moon, Charon.

“We’re very excited to approve names recognising people of significance to Pluto and the pursuit of exploration as well as the mythology of the underworld. These names highlight the importance of pushing to the frontiers of discovery,” said Rita Schulz, chair of the IAU Working Group for Planetary System Nomenclature. “We appreciate the contribution of the general public in the form of their naming suggestions and the New Horizons team for proposing these names to us.”

More names are expected to be proposed to the IAU, both for Pluto and for its moons. “The approved designations honour many people and space missions who paved the way for the historic exploration of Pluto and the Kuiper Belt, the most distant worlds ever explored,” said Alan Stern, New Horizons Principal Investigator from the Southwest Research Institute (SwRI) in Boulder, Colorado.

The approved Pluto surface feature names are listed below.

Tombaugh Regio honours Clyde Tombaugh (1906–1997), the U.S. astronomer who discovered Pluto in 1930 from Lowell Observatory in Arizona.

Burney crater honors Venetia Burney (1918–2009), who as an 11-year-old schoolgirl suggested the name “Pluto” for Clyde Tombaugh’s newly discovered planet. Later in life she taught mathematics and economics.

Sputnik Planitia is a large plain named after Sputnik 1, the first space satellite, launched by the Soviet Union in 1957.

Tenzing Montes and Hillary Montes are mountain ranges honouring Tenzing Norgay (1914–1986) and Sir Edmund Hillary (1919–2008), the Indian/Nepali Sherpa and New Zealand mountaineer who were the first to reach the summit of Mount Everest and return safely.

Al-Idrisi Montes honours Ash-Sharif al-Idrisi (1100–1165/66), a noted Arab mapmaker and geographer whose landmark work of medieval geography is sometimes translated as “The Pleasure of Him Who Longs to Cross the Horizons.”

Djanggawul Fossae defines a network of long, narrow depressions named for the Djanggawuls, three ancestral beings in indigenous Australian mythology who travelled between the island of the dead and Australia, creating the landscape and filling it with vegetation.

Sleipnir Fossa is named for the powerful, eight-legged horse of Norse mythology that carried the god Odin into the underworld.

Virgil Fossae honors Virgil, one of the greatest Roman poets and Dante’s fictional guide through hell and purgatory in the Divine Comedy.

Adlivun Cavus is a deep depression named for Adlivun, the underworld in Inuit mythology.

Hayabusa Terra is a large land mass saluting the Japanese spacecraft and mission (2003–2010) that returned the first asteroid sample.

Voyager Terra honours the pair of NASA spacecraft, launched in 1977, that performed the first “grand tour” of all four giant planets. The Voyager spacecraft are now probing the boundary between the Sun and interstellar space.

Tartarus Dorsa is a ridge named for Tartarus, the deepest, darkest pit of the underworld in Greek mythology.

Elliot crater recognises James Elliot (1943–2011), an MIT researcher who pioneered the use of stellar occultations to study the Solar System — leading to discoveries such as the rings of Uranus and the first detection of Pluto’s thin atmosphere.

Getting NASA’s Pluto mission off the ground took blood, sweat and years. Alan Stern dishes about the new book ‘Chasing New Horizons’: here.

Never-before-seen dunes on Pluto spotted in New Horizons images. Wind and a process called sublimation helped sculpt the ripples, a new study suggests. By Lisa Grossman, 2:01pm, May 31, 2018.

Icy volcanoes on Pluto may have spewed organic-rich water. The dwarf planet has short-lived ammonia on its icy surface. By Lisa Grossman, 2:00pm, May 29, 2019.

Spacecraft halfway from Pluto to dwarf planet 2014 MU69

This video says about itself:

9 January 2017

NASA’s New Horizons spacecraft has now traveled half the distance from Pluto – its storied first target – to 2014 MU69, the Kuiper Belt object it will fly past on Jan. 1, 2019.

From Sci-news.com:

NASA’s New Horizons Spacecraft Halfway from Pluto to Kuiper Belt Object 2014 MU69

Apr 4, 2017 by Enrico de Lazaro

Continuing on its path through the outer regions of our Solar System, New Horizons has now traveled half the distance from the dwarf planet Pluto to its next target, the Kuiper Belt object 2014 MU69.

New Horizons is currently 486.19 million miles (782.45 million km) from 2014 MU69 and approximately 3.5 billion miles (5.7 billion km) from Earth.

“It’s fantastic to have completed half the journey to our next flyby,” said New Horizons principal investigator Dr. Alan Stern, from the Southwest Research Institute.

“That flyby will set the record for the most distant world ever explored in the history of civilization.”

2014 MU69 was discovered on June 26, 2014 by astronomers using the NASA/ ESA Hubble Space Telescope.

Also known as 1110113Y, it orbits the Sun once every 293 years.

According to NASA scientists, 2014 MU69 is a relatively small Kuiper Belt object (KBO).

It is estimated to have a diameter of 30 miles (48 km) — that’s more than 10 times larger and 1,000 times more massive than typical comets, but only about 0.5 to 1% of the size (and about 1/10,000th the mass) of Pluto.

The surface of this KBO is just as red as, if not redder than, Pluto’s surface.

New Horizons’ planned rendezvous with 2014 MU69 is January 1, 2019.

“The January 2019 MU69 flyby is the next big event for us, but New Horizons is truly a mission to more broadly explore the Kuiper Belt,” said New Horizons project scientist Dr. Hal Weaver, from the Johns Hopkins Applied Physics Laboratory.

“In addition to 2014 MU69, we plan to study more than two-dozen other KBOs in the distance and measure the charged particle and dust environment all the way across the Kuiper Belt.”

Why it’s good news that Pluto doesn’t have rings. New Horizons’ next destination might be ring-free, too, promising a safe passage for the spacecraft. By Lisa Grossman, 11:30am, October 4, 2017.

New Horizons’ next target might have a moon. The Kuiper Belt object MU69 may have a smaller companion: here.

Dwarf planet Pluto news

This video says about itself:

22 March 2017

Researchers investigating Pluto think they have determined how the dwarf planet gets its red spots.

According to scientists with NASA‘s New Horizons mission, the hazy atmosphere is filled with particles that settle onto the surface.

In some areas, where the atmosphere has collapsed, the particles on the surface are exposed to more radiation from space that darkens them.

The researchers used data from a flyby mission in 2015.

Instruments onboard the New Horizons spacecraft found that the haze of particles reaches about 200 kilometers above the surface with 20 distinct layers.

From Science News:

How Pluto’s haze could explain its red spots

Collapse of atmosphere may influence blotchy surface colors

By Ashley Yeager

9:41am, March 22, 2017

Pluto may get its smattering of red spots from the fallout of its hazy blue skies, researchers say.

Haze particles from the dwarf planet’s atmosphere settle onto all of Pluto’s surface. But some regions may become redder and darker than others because parts of the atmosphere collapse, exposing those spots to more surface-darkening radiation from space, researchers report March 22 at the Lunar and Planetary Science Conference in The Woodlands, Texas.

“The atmospheric haze on Pluto was a spectacular surprise,” says NASA New Horizons mission scientist Andrew Cheng, a physicist at Johns Hopkins University. When the New Horizons spacecraft flew past Pluto in 2015, scientists weren’t expecting to see haze reaching at least 200 kilometers above the dwarf planet’s surface; nor were they expecting to see the haze divided into about 20 delicate and distinct layers (SN Online: 10/15/15).

These discoveries led researchers to suspect that the layers formed as a result of weak winds blowing across Pluto’s surface and over its mountains. Cheng and colleagues describe how the winds would shape the haze layers in a paper accepted in Icarus and posted online February 24 at arXiv.org. The team also explains how the atmosphere may affect the color of the dwarf planet’s surface features.

“Haze particles continually fall out onto the surface and rapidly build up,” Cheng says. This process should effectively “paint” the entire surface a uniform color — but Pluto isn’t a single color. It has strikingly bright and dark terrains, with some of the highest contrast found in the solar system. These dark and light regions form because portions of Pluto’s atmosphere periodically collapse, with air freezing and falling onto the dwarf planet’s surface, he and colleagues suggest.

When a section of the atmosphere collapses, parts of the surface are exposed directly to radiation from space, which would darken the surface particles there, Cheng explains. The richness of the reds, the team says, cannot be explained without some kind of collapse of the atmosphere, which does eventually redevelop.

Observations from NASA’s Kepler spacecraft also support the idea that Pluto’s atmosphere collapses. In fact, as Pluto moves away from the sun, most, if not all, of its atmosphere may collapse onto the dwarf planet’s surface, reported Carey Lisse, also of Johns Hopkins University, at the conference.

Exactly how much of Pluto’s atmosphere freezes out during its year, which lasts for 248 Earth years, isn’t clear. But that is currently being monitored, says Timothy Dowling, an atmospheric scientist at the University of Louisville in Kentucky, who was not involved in the new work. Pluto, he notes, won’t complete the first lap that humans have watched it make around the sun until 2178.

MAKE PLUTO A PLANET AGAIN A group of scientists have boarded the cause, as they know it’s pretty great. [HuffPost]

It’s time to redefine what qualifies as a planet, scientists propose. Redefinition would add Pluto back to the list, plus about 100 more. By
Ashley Yeager, 9:00am, March 23, 2017: here.

New Horizons’ next target caught making a star blink. Knowing object’s specs will help plan Pluto spacecraft’s 2019 flyby of MU69, by Lisa Grossman. 7:00am, July 20, 2017.

New Horizons’ next target has been dubbed Ultima Thule. The name was chosen from about 34,000 submissions. By Mike Denison, 3:52pm, March 14, 2018.

Liquid water on dwarf planet Pluto?

This 22 June 2016 video says about itself:

Does Pluto ocean holds alien life? Dwarf planet liquid water lurking under icy surface.

From Brown University in the USA:

Research bolsters case for a present-day subsurface ocean on Pluto

June 21, 2016

An updated thermal model for Pluto suggests that liquid water beneath the dwarf planet’s ice shell may not be frozen yet.

PROVIDENCE, R.I. [Brown University] — When the NASA’s New Horizons spacecraft buzzed by Pluto last year, it revealed tantalizing clues that the dwarf planet might have — or had at one time — a liquid ocean sloshing around under its icy crust. According to a new analysis led by a Brown University Ph.D. student, such an ocean likely still exists today.

The study, which used a thermal evolution model for Pluto updated with data from New Horizons, found that if Pluto’s ocean had frozen into oblivion millions or billions of years ago, it would have caused the entire planet to shrink. But there are no signs of a global contraction to be found on Pluto’s surface. On the contrary, New Horizons showed signs that Pluto has been expanding.

“Thanks to the incredible data returned by New Horizons, we were able to observe tectonic features on Pluto’s surface, update our thermal evolution model with new data and infer that Pluto most likely has a subsurface ocean today,” said Noah Hammond, a graduate student in Brown’s Department of Earth, Environmental and Planetary Sciences, and the study’s lead author.

The research, which Hammond coauthored with advisors Amy Barr of the Planetary Science Institute in Arizona and Brown University geologist Marc Parmentier, is in press in Geophysical Research Letters.

The pictures New Horizons sent back from its close encounter with the Kuiper Belt’s most famous denizen showed that Pluto was much more than a simple snowball in space. It has an exotic surface made from different types of ices — water, nitrogen and methane. It has mountains hundreds of meters high and a vast heart-shaped plain. It also has giant tectonic features — sinuous faults hundreds of kilometers long as deep as 4 kilometers. It was those tectonic features that got scientists thinking that a subsurface ocean was a real possibility for Pluto.

“What New Horizons showed was that there are extensional tectonic features, which indicate that Pluto underwent a period of global expansion,” Hammond said. “A subsurface ocean that was slowly freezing over would cause this kind of expansion.”

Scientists think that there may have been enough heat-producing radioactive elements within Pluto’s rocky core to melt part of the planet’s ice shell. Over time in the frigid Kuiper belt, that melted portion would eventually start to refreeze. Ice is less dense than water, so when it freezes, it expands. If Pluto had an ocean that was frozen or in the process of freezing, extensional tectonics on the surface would result, and that’s what New Horizons saw.

There aren’t many other ways on Pluto to get such features. One way might have been through a gravitational tug of war with its moon, Charon. But the active gravitational dynamics between the two have long since wound down, and some of the tectonics look fairly fresh (on a geologic timescale). So, many scientists believe that an ocean is the strongest scenario.

But if Pluto had an ocean, what is its fate today? Could the freezing process still be going on, or did the ocean freeze solid a billion years ago?

That’s where the thermal evolution model run by Hammond and his colleagues comes in. The model includes updated data from New Horizons on Pluto’s diameter and density, key parameters in understanding the dynamics in Pluto’s interior. The model showed that because of the low temperatures and high pressure within Pluto, an ocean that had completely frozen over would quickly convert from the normal ice we all know to a different phase called ice II. Ice II has a more compact crystalline structure than standard ice, so an ocean frozen to ice II would occupy a smaller volume and lead to a global contraction on Pluto, rather than an expansion.

“We don’t see the things on the surface we’d expect if there had been a global contraction,” Hammond said. “So we conclude that ice II has not formed, and therefore that the ocean hasn’t completely frozen.”

There are a few caveats, the researchers point out. The formation of ice II is dependent on the thickness of Pluto’s ice shell. Ice II only forms if the shell is 260 kilometers thick or more. If the shell is thinner than that, the ocean could have frozen without forming ice II. And if that were the case the ocean could have frozen completely without causing contraction.

However, the researchers say there’s good reason to believe that the ice shell is more than 260 kilometers. Their updated model suggests that Pluto’s ice shell is actually closer to 300 or more kilometers thick. In addition, the nitrogen and methane ices that New Horizons found on the surface bolster the case for a thick ice shell.

“Those exotic ices are actually good insulators,” Hammond said. “They may be helping Pluto from losing more of its heat to space.”

Taken together, the new model bolsters the case for an ocean environment in the furthest reaches of the solar system.

“That’s amazing to me,” Hammond said. “The possibility that you could have vast liquid water ocean habitats so far from the sun on Pluto — and that the same could also be possible on other Kuiper belt objects as well — is absolutely incredible.”

The research was supported by the NASA Earth and Space Science Fellowship (NNX13AN99H) and NASA Planetary Geology & Geophysics (NNX15AN79G).

It has been one year since the New Horizons spacecraft finished its historic flyby of Pluto and its system of moons, taking the most detailed images ever of the dwarf planet and its companions. Since then, the probe has been steadily sending back every bit of data it collected in its 22-hour encounter, revealing an increasingly complex system: here.

X-ray mystery shrouds Pluto. Despite wrong conditions, handful-plus of photons detected streaming from dwarf planet. By Christopher Crockett, 6:00am, November 7, 2016: here.

Unknown big planet in the solar system?

This October 2019 video is called Planet 9 Could Be a Black Hole?! | SciShow News.

A 2014 video used to be called Kuiper Belt Objects and Io, Europa & Triton.

From daily The Independent in Britain today:

Planet 9: Secret, dark world could be hiding in our solar system

The mysterious object has been spotted disturbing the movement of smaller objects in the outer solar system — but is too far away to be spotted directly

Andrew Griffin

A huge planet might be sitting at the edge of our solar system without ever being seen.

The world — which could be about ten times as massive as Earth — would be large enough to become the ninth planet of our solar system.

The planet hasn’t yet been seen by scientists. Instead, they have found it by watching the way that dwarf planets and other objects in the outer solar system move — their orbits seem to be disturbed by something huge but hidden sitting out there.

“If there’s going to be another planet in the solar system, I think this is it,” Greg Laughlin of the University of California, Santa Cruz told National Geographic. “It would be quite extraordinary if we had one. Fingers crossed. It would be amazing.”

If the planet exists, it is thought to be about ten times as massive or three times as large as Earth. That sort of sized planet occurs throughout the universe — but has been an obvious omission from our own.

“This would be a real ninth planet,” says Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy. “There have only been two true planets discovered since ancient times, and this would be a third. It’s a pretty substantial chunk of our solar system that’s still out there to be found, which is pretty exciting.”

It would be around 200 to 300 times as far away from the sun as when it gets closest to the star, scientists say. It will spend some of its time as much as four times as far away as that, and an entire orbit of the sun probably takes about 20,000 years.

The planet might have made its way out to the edge of the universe when it was thrown out there by the gravity of Jupiter or Saturn, the scientists suggest.

At such distances, the planet could be impossible to spot — even with the two huge telescopes that are currently looking for it. So little light is sent back from that far away that it might never make it back for us to see.

It is surrounded by much brighter lights — even the distant Pluto could be about 10,000 times brighter — and so scientists have to be sure that they point telescopes at exactly the right point and pick out an already very unlikely speck of light.

That’s why the scientists have spotted the potential planet by seeing the disturbances that it is causing in the gravitational field of the far star system. There appears to be a “great perturber” upsetting the movement of other objects in that far away region, and the new paper — authored by Michael Brown and Konstantin Batygin and published in the Astronomical Journal — claims that is being caused by a mysterious, unknown world.

The solar system doesn’t often change. The only recent addition was Pluto, which was found in 1930 and spent most of the 21st century as its most distant and smallest planet — until it was controversially downgraded to being just a dwarf planet, and the solar system went back to having eight members.

If the new planet is real, then it will definitely be a planet, scientists say. Since it dominates a bigger region than any of the other planets, it would “the most planet-y of the planets in the whole solar system”, Brown said.

The downgrading of Pluto was partly the result of work by astronomer Michael Brown, who co-wrote the new paper. He had found that Pluto was surrounded by a huge number of similarly-sized planets, and the International Astronomical Union decided that Pluto would be excluded from a new definition.

The two astronomers found the new potential planet while they were looking at those small rocks. They seemed to fly around on orbits that couldn’t be happening by chance, and instead were best explained by a big ninth planet sitting out there with them.

A ninth planet has long been hypothesised — and become the basis of some conspiracy theories — originally going under the name Planet X. It was first talked about more than a century ago, and looking for that planet was what brought astronomers to find Pluto.

This video from the USA says about itself:

20 January 2016

Caltech’s Konstantin Batygin, an assistant professor of planetary science, and Mike Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy, discuss new research that provides evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer solar system.

Planet Pluto’s moon Charon, new images

This video from the USA says about itself:

1 October 2015

Images from NASA’s New Horizons spacecraft were used to create this flyover video of Pluto‘s largest moon, Charon. The “flight” starts with the informally named Mordor (dark) region near Charon’s north pole. The camera then moves south to a vast chasm, descending from 1,100 miles (1,800 kilometers) to just 40 miles (60 kilometers) above the surface to fly through the canyon system. From there it’s a turn to the south to view the plains and “moat mountain,” informally named Kubrick Mons, a prominent peak surrounded by a topographic depression.

New Horizons Long-Range Reconnaissance Imager (LORRI) photographs showing details at up to 400 meters per pixel were used to create the basemap for this animation. Those images, along with pictures taken from a slightly different vantage point by the spacecraft’s Ralph/ Multispectral Visible Imaging Camera (MVIC), were used to create a preliminary digital terrain (elevation) model. The images and model were combined and super-sampled to create this animation.

Credit: NASA/JHUAPL/SwRI/Stuart Robbins

From Space.com:

October 01, 2015 04:29pm ET

Amazing new images show the enormous canyon system on Pluto‘s big moon Charon in unprecedented detail.

The photos were captured by NASA’s New Horizons spacecraft during its historic flyby of Pluto on July 14. Mission team members combined some of the images into a new video that lets viewers fly over Charon’s tortured surface.

Charon’s huge chasm snakes across the moon’s surface for more than 1,000 miles (1,600 kilometers). It’s at least four times longer than Arizona’s Grand Canyon, and twice as deep in places, New Horizons team members said. (Some parts of the Grand Canyon are more than 1 mile, or 1.6 km, deep.) [See more Pluto photos by New Horizons]

Pluto as we know it now: Nasa report unwraps enigma of dwarf planet. Researchers present collection of New Horizons data, revealing water icebergs on ‘a surface unlike any planetary surface we’ve ever seen before’: here.

Source of Charon’s red north pole is probably Pluto, by Christopher Crockett, 1:00pm, September 14, 2016: here.