Pluto Archives

May 1, 2016May 2, 2016 by Ken Kremer

Scientists Assemble Fresh Global Map of Pluto Comprising Sharpest Flyby Images

NASA’s New Horizons mission science team has produced this updated panchromatic (black-and-white) global map of Pluto. Credits: NASA/JHUAPL/SWRI

NASA’s New Horizons mission science team has produced this updated panchromatic (black-and-white) global map of Pluto. The map includes all resolved images of Pluto’s surface acquired at pixel resolutions ranging from 18 miles (30 kilometers) on the Charon-facing hemisphere (left and right edges of the map) to 770 feet (235 meters) on the hemisphere facing New Horizons during the closest approach on July 14, 2015 (map center). Credits: NASA/JHUAPL/SWRI — NASA’s New Horizons mission science team has produced this updated panchromatic (black-and-white) global map of Pluto. Credits: NASA/JHUAPL/SWRI

The science team leading NASA’s New Horizons mission that unveiled the true nature of Pluto’s long hidden looks during the history making maiden close encounter last July, have published a fresh global map that offers the sharpest and most spectacular glimpse yet of the mysterious, icy world.

The newly updated global Pluto map is comprised of all the highest resolution images transmitted back to Earth thus far and provides the best perspective to date.

Click on the lead image above to enjoy Pluto revealed at its finest thus far. Click on this link to view the highest resolution version.

Prior to the our first ever flyby of the Pluto planetary system barely 8 months ago, the planet was nothing more than a fuzzy blob with very little in the way of identifiable surface features – even in the most powerful telescopic views lovingly obtained from the Hubble Space Telescope (HST).

Dead center in the new map is the mesmerizing heart shaped region informally known as Tombaugh Regio, unveiled in all its glory and dominating the diminutive world.

The panchromatic (black-and-white) global map of Pluto published by the team includes the latest images received as of less than one week ago on April 25.

The images were captured by New Horizons’ high resolution Long Range Reconnaissance Imager (LORRI).

The science team is working on assembling an updated color map.

During its closest approach at approximately 7:49 a.m. EDT (11:49 UTC) on July 14, 2015, the New Horizons spacecraft swoop to within about 12,500 kilometers (nearly 7,750 miles) of Pluto’s surface and about 17,900 miles (28,800 kilometers) from Charon, the largest moon.

The map includes all resolved images of Pluto’s surface acquired in the final week of the approach period ahead of the flyby starting on July 7, and continuing through to the day of closest approach on July 14, 2015 – and transmitted back so far.

The pixel resolutions are easily seen to vary widely across the map as you scan the global map from left to right – depending on which Plutonian hemisphere was closest to the spacecraft during the period of close flyby.
They range from the highest resolution of 770 feet (235 meters), at center, to 18 miles (30 kilometers) at the far left and right edges.

The Charon-facing hemisphere (left and right edges of the map) had a pixel resolution of 18 miles (30 kilometers).

“This non-encounter hemisphere was seen from much greater range and is, therefore, in far less detail,” noted the team.

However the hemisphere facing New Horizons during the spacecraft’s closest approach on July 14, 2015 (map center) had a far higher pixel resolution reaching to 770 feet (235 meters).

Coincidentally and fortuitously the spectacularly diverse terrain of Tombaugh Regio and the Sputnik Planum area of the hearts left ventricle with ice flows and volcanoes, mountains and river channels was in the region facing the camera and sports the highest resolution imagery.

See below a newly released shaded relief map of Sputnik Planum.

This new shaded relief view of the region surrounding the left side of Pluto’s heart-shaped feature – informally named Sputnik Planum – shows that the vast expanse of the icy surface is on average 2 miles (3 kilometers) lower than the surrounding terrain. Angular blocks of water ice are “floating” in the bright deposits of softer, denser solid nitrogen. Credits: NASA/JHUAPL/SwRI

“Sputnik Planum – shows that the vast expanse of the icy surface is on average 2 miles (3 kilometers) lower than the surrounding terrain. Angular blocks of water ice along the western edge of Sputnik Planum can be seen “floating” in the bright deposits of softer, denser solid nitrogen,” according to the team.

Even more stunning images and groundbreaking data will continue streaming back from New Horizons until early fall, across over 3 billion miles of interplanetary space.

Thus the global map of Pluto will be periodically updated.

Its taking over a year to receive the full complement of some 50 gigabits of data due to the limited bandwidth available from the transmitter on the piano-shaped probe as it hurtled past Pluto, its largest moon Charon and four smaller moons.

Pluto is the last planet in our solar system to be visited in the initial reconnaissance of planets by spacecraft from Earth since the dawn of the Space Age.

This new global mosaic view of Pluto was created from the latest high-resolution images to be downlinked from NASA’s New Horizons spacecraft and released on Sept. 11, 2015. The images were taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers). This new mosaic was stitched from over two dozen raw images captured by the LORRI imager and colorized. Annotated with informal place names. Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Marco Di Lorenzo/Ken Kremer/kenkremer.com

New Horizons remains on target to fly by a second Kuiper Belt Object (KBO) on Jan. 1, 2019 – tentatively named PT1, for Potential Target 1. It is much smaller than Pluto and was recently selected based on images taken by NASA’s Hubble Space Telescope.

Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.

Ken Kremer

April 22, 2016April 26, 2016 by Matt Williams

How Do We Terraform Jupiter’s Moons?

Surface features of the four members at different levels of zoom in each row

Continuing with our “Definitive Guide to Terraforming“, Universe Today is happy to present to our guide to terraforming Jupiter’s Moons. Much like terraforming the inner Solar System, it might be feasible someday. But should we?

Fans of Arthur C. Clarke may recall how in his novel, 2010: Odyssey Two (or the movie adaptation called 2010: The Year We Make Contact), an alien species turned Jupiter into a new star. In so doing, Jupiter’s moon Europa was permanently terraformed, as its icy surface melted, an atmosphere formed, and all the life living in the moon’s oceans began to emerge and thrive on the surface.

As we explained in a previous video (“Could Jupiter Become a Star“) turning Jupiter into a star is not exactly doable (not yet, anyway). However, there are several proposals on how we could go about transforming some of Jupiter’s moons in order to make them habitable by human beings. In short, it is possible that humans could terraform one of more of the Jovians to make it suitable for full-scale human settlement someday.

Continue reading “How Do We Terraform Jupiter’s Moons?”

April 19, 2016May 5, 2016 by Evan Gough

Gravity Waves On Pluto?

The varying brightness in Pluto's atmosphere is caused by atmospheric gravity waves, or buoyancy waves. Image: NASA/New Horizons/Johns Hopkins APL/SWRI

New Horizons’ historic journey to Pluto and beyond continues to provide surprises. As data from the spacecraft’s close encounter with Pluto and its moons arrives at Earth, scientists are piecing together an increasingly intriguing picture of the dwarf planet. The latest discovery is centred around Pluto’s atmosphere, and what are called ‘atmospheric gravity waves.’

Atmospheric gravity waves are a different phenomenon than the gravity waves that were detected for the first time in February, 2016. Those gravity waves are ripples in the fabric of space time, first predicted by Albert Einstein back in 1916. After years of searching, the LIGO instrument detected gravity waves that resulted from two black holes colliding. The discovery of what you might call ‘Einsteinian Gravity Waves’ may end up revolutionizing astronomy.

New Horizons has revealed surprise after surprise in its study of Pluto. Its atmosphere has turned out to be much more complex than anybody expected. It’s composed of 90% nitrogen, with extensive haze layers. Scientists have discovered that Pluto’s atmosphere can vary in brightness depending on viewpoint and illumination, while the vertical structure of the layered haze remains unchanged.

Scientists studying the New Horizons’ data think that atmospheric gravity waves, also called buoyancy waves, are responsible. Atmospheric gravity waves are known to exist on only two other planets; Earth and Mars. They are typically caused by wind flowing over obstructions like mountain ranges.

The layers in Pluto’s atmosphere, and their varying brightness, are most easily seen when they are backlit by the Sun. This was the viewpoint New Horizons had when it captured these images on its departure from Pluto on July 14, 2015. The spacecraft’s Long Range Reconnaissance Imager (LORRI) captured them, using time intervals of 2 to 5 hours. What they show is the brightness of the layers changing by 30% without any change in their height above the surface of the planet.

LORRI, as its name suggests, is a long range image capture instrument. It also captures high resolution geologic data, and was used to map Pluto’s far side. The principal investigator for LORRI is Andy Cheng, from the Applied Physics Laboratory at Johns Hopkins University, in Maryland. “Pluto is simply amazing,” said Andy Cheng. “When I first saw these images and the haze structures that they reveal, I knew we had a new clue to the nature of Pluto’s hazes. The fact that we don’t see the haze layers moving up or down will be important to future modelling efforts.”

Overall, Pluto and its system of moons has turned out to be a much more dynamic place than previously thought. A geologically active landscape, possible ice volcanoes, eroding cliffs made of methane ice, and more, have woken us up to Pluto’s complexity. But its atmosphere has turned out to be just as complex and puzzling.

New Horizons has departed the Pluto system now, and is headed for the Kuiper Belt. The Kuiper Belt is considered a relic of the early Solar System. New Horizons will visit another icy world there, and hopefully continue on to the edge of the heliosphere, the same way the Voyage probes have. New Horizons has enough energy to last until approximately the mid-2030’s, if all goes well.

April 19, 2016May 5, 2016 by Matt Williams

NASA Invests In Radical Game-Changing Concepts For Exploration

Artist's concept of some of the Phase I winners of the 2016 NIAC program. Credit: NASA

Every year, the NASA Innovative Advanced Concepts (NIAC) program puts out the call to the general public, hoping to find better or entirely new aerospace architectures, systems, or mission ideas. As part of the Space Technology Mission Directorate, this program has been in operation since 1998, serving as a high-level entry point to entrepreneurs, innovators and researchers who want to contribute to human space exploration.

This year, thirteen concepts were chosen for Phase I of the NIAC program, ranging from reprogrammed microorganisms for Mars, a two-dimensional spacecraft that could de-orbit space debris, an analog rover for extreme environments, a robot that turn asteroids into spacecraft, and a next-generation exoplanet hunter. These proposals were awarded $100,000 each for a nine month period to assess the feasibility of their concept.

Continue reading “NASA Invests In Radical Game-Changing Concepts For Exploration”

April 4, 2016April 4, 2016 by Ken Kremer

New Horizons Snaps Amazing 3-D View of Pluto’s Mysterious ‘Bladed’ Terrain

The amazing stereo view of a broad area informally named Tartarus Dorsa combines two images from the Ralph/Multispectral Visible Imaging Camera (MVIC) taken about 14 minutes apart on July 14, 2015. The first was taken when New Horizons was 16,000 miles (25,000 kilometers) away from Pluto, the second when the spacecraft was 10,000 miles (about 17,000 kilometers) away. Credits: NASA/JHUAPL/SwRI

It’s time to whip out your 3-D glasses to enjoy and scrutinize the remarkable detail of spectacular terrain revealed in a new high resolution stereo image of Pluto – King of the Kuiper Belt! – taken by NASA’s New Horizons spacecraft.

The amazing new stereo Plutonian image focuses on an area dominated by a mysterious feature that geologists call ‘bladed’ terrain – seen above – and its unlike anything seen elsewhere in our solar system.

Its located in a broad region of rough highlands informally known as Tartarus Dorsa – situated to the east of the Pluto’s huge heart shaped feature called Tombaugh Regio. The best resolution is approximately 1,000 feet (310 meters).

The stereo view combines a pair of images captured by New Horizons Ralph/Multispectral Visible Imaging Camera (MVIC) science instruments. They were taken about 14 minutes apart on during history making first ever flyby of the Pluto planetary system on July 14, 2015.

The first was taken when New Horizons was 16,000 miles (25,000 kilometers) away from Pluto, the second when the spacecraft was 10,000 miles (about 17,000 kilometers) away.

The blades align from north to south, typically reach up to about 550 yards (500 meters) high and are spaced about 2-4 miles (3-5 kilometers). Thus they are among the planets steepest features. They are “perched on a much broader set of rounded ridges that are separated by flat valley floors,” according to descriptions from the New Horizons science team.

This color image of Pluto taken by NASA’s New Horizons spacecraft shows rounded and bizarrely textured mountains, informally named the Tartarus Dorsa, rise up along Pluto’s terminator and show intricate but puzzling patterns of blue-gray ridges and reddish material in between. This view, roughly 330 miles (530 kilometers) across, combines blue, red and infrared images taken by the Ralph/Multispectral Visual Imaging Camera (MVIC) on July 14, 2015, and resolves details and colors on scales as small as 0.8 miles (1.3 kilometers). Credits: NASA/JHUAPL/SWRI

Mission scientists have also noted that the bladed terrain has the texture of “snakeskin” owing to their “scaly raised relief.”

In the companion global image from NASA (below), the bladed terrain is outlined in red and shown to extend quite far to the east of Tombaugh Regio.

The composite image was taken on July 13, 2015, the day before the closest approach flyby, when the probe was farther away thus shows lower resolution. It combines a pair of images from two of the science instruments – a Ralph/Multispectral Visible Imaging Camera (MVIC) color scan and an image from the Long Range Reconnaissance Imager (LORRI).

This global view of Pluto combines a Ralph/Multispectral Visible Imaging Camera (MVIC) color scan and an image from the Long Range Reconnaissance Imager (LORRI), both obtained on July 13, 2015 – the day before New Horizons’ closest approach. The red outline marks the large area of mysterious, bladed terrain extending from the eastern section of the large feature informally named Tombaugh Regio. Credits: NASA/JHUAPL/SwRI — This global view of Pluto combines a Ralph/Multispectral Visible Imaging Camera (MVIC) color scan and an image from the Long Range Reconnaissance Imager (LORRI), both obtained on July 13, 2015 – the day before New Horizons’ closest approach. The red outline marks the large area of mysterious, bladed terrain extending from the eastern section of the large feature informally named Tombaugh Regio.
Credits: NASA/JHUAPL/SwRI

The MVIC scan was taken from a range of 1 million miles (1.6 million kilometers), at a resolution of 20 miles (32 kilometers) per pixel. The corresponding LORRI image was obtained from roughly the same range, but has a higher spatial resolution of 5 miles (8 kilometers) per pixel, say officials.

Scientists have developed several possible theories about the origins of the bladed terrain, including erosion from evaporating ices or deposition of methane ices.

Measurements from the Linear Etalon Imaging Spectral Array (LEISA) instrument reveal that that this region “is composed of methane (CH4) ice with a smattering of water,” reports New Horizons researcher Orkan Umurhan.

He speculates that “the material making up the bladed terrain is a methane clathrate. A clathrate is a structure in which a primary molecular species (say water, or H2O) forms a crystalline ‘cage’ to contain a guest molecule (methane or CH4, for example).”

But the question of whether that methane ice is strong enough to maintain the steep walled snakeskin features, will take much more research to determine a conclusive answer.

Umurhan suggests that more research could help determine if the “methane clathrates in the icy moons of the outer solar system and also in the Kuiper Belt were formed way back before the solar system formed – i.e., within the protosolar nebula – potentially making them probably some of the oldest materials in our solar system.”

Pluto continues to amaze and surprise us as the data streams back to eagerly waiting scientists on Earth over many more months to come – followed by years and decades of painstaking analysis.

During New Horizons flyby on July 14, 2015, it discovered that Pluto is the biggest object in the outer solar system and thus the ‘King of the Kuiper Belt.”

The Kuiper Belt comprises the third and outermost region of worlds in our solar system.

Pluto is the last planet in our solar system to be visited in the initial reconnaissance of planets by spacecraft from Earth since the dawn of the Space Age.

Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.

Ken Kremer

………….

Learn more about NASA Mars rovers, Orion, SLS, ISS, Orbital ATK, ULA, SpaceX, Boeing, Space Taxis, NASA missions and more at Ken’s upcoming outreach events:

Apr 9/10: “NASA and the Road to Mars Human Spaceflight programs” and “Curiosity explores Mars” at NEAF (NorthEast Astronomy and Space Forum), 9 AM to 5 PM, Suffern, NY, Rockland Community College and Rockland Astronomy Club – http://rocklandastronomy.com/neaf.html

Apr 12: Hosting Dr. Jim Green, NASA, Director Planetary Science, for a Planetary sciences talk about “Ceres, Pluto and Planet X” at Princeton University; 7:30 PM, Amateur Astronomers Assoc of Princeton, Peyton Hall, Princeton, NJ – http://www.princetonastronomy.org/

Apr 17: “NASA and the Road to Mars Human Spaceflight programs”- 1:30 PM at Washington Crossing State Park, Nature Center, Titusville, NJ – http://www.state.nj.us/dep/parksandforests/parks/washcros.html

March 23, 2016April 12, 2016 by Evan Gough

High Albedo Points To Huge Collision Forming Plutonian System

Data from New Horizons supports the theory that Pluto's 4 small moons were formed as a result of a collision. Image by NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

The high albedo (reflectivity) of some of Pluto’s moons supports the theory that those moons were formed as a result of a collision, rather than being Kuiper Belt Objects (KBOs) that wandered too close and were captured by Pluto’s gravity. Data supporting the collision theory came from NASA’s New Horizons spacecraft as it flew by Pluto in July 2015.

The Pluto system is a complex one. Pluto has 5 moons: Charon, Styx, Nix, Kerberos, and Hydra. Charon is the only moon that is tidally locked with Pluto, and the two are sometimes called a double dwarf planet. The system’s barycenter lies between Pluto and Charon, though much closer to Pluto. The objects in the system move in near-circular orbits, rather than ellipses.

Pluto and Charon were thought to have formed the same way the other planets formed in the Solar System; by coalescing out of a ring of debris left over after the Sun formed. Then, it was thought, the other Plutonian moons were captured from the Kuiper Belt. Pluto resides in the Kuiper Belt, so this made sense. Some of the other moons in our Solar System, like Neptune’s Triton and Saturn’s Phoebe, are also thought to be captured Kuiper Belt Objects (KBOs).

A competing theory for the formation of the Pluto system is the collision theory. This theory states that Pluto and Charon did indeed coalesce out of the ring of debris around the Sun, and that Charon was itself a dwarf planet. But a collision occurred after that, about 4 or 4.5 billion years ago, between Pluto and an object about the same size as Pluto.

This collision left Pluto and Charon in their binary state, but created a circumbinary disk of debris out of which the other 4 moons formed. There are competing versions of these theories, one of which suggests that all of Pluto’s 5 moons were formed by this collision, and none coalesced out of the circumstellar disk of debris that the other planets were formed from.

New Horizons has delivered measurements and data showing that the albedo of Pluto’s 4 smallest moons is much too high for captured KBOs. Their surface reflectivity is highly suggestive of a water-ice composition. Measured KBOs have a geometric albedo of less than .20, while Styx, Nix, Hydra, and Kerberos have values of .40, .57, .56, and .45 respectively. This points to the idea that the object that collided with Pluto 4 to 4.5 billion years ago had at least some icy surface layers.

Pluto’s 4 small moons, Styx, Nix, Kerberos, and Hydra, are all non-spheroidal. This also points to their origins as conglomerated objects which formed from a collision-induced debris disk, rather than as captured Kuiper Belt objects.

These results were published in the journal Science, on March 18th, 2016. They were gathered using the Long-Range Reconnaissance Imager (LORRI), and the Multispectral Visible Imaging Camera (MVIC) instruments on board New Horizons.

Half of the data from New Horizons’ visit to Pluto is yet to arrive, including data from the Linear Etalon Imaging Spectral Array (LEISA). Scientists are hopeful that this data, and all the existing data which together will take years to analyze, will answer some of the questions surrounding the formation of the Pluto system.

March 22, 2016April 12, 2016 by Evan Gough

Ancient Pluto May Have Had Lakes And Rivers Of Nitrogen

The New Horizons team used "principal component analysis" to get this false-color image that highlights the different regions of Pluto. Image: NASA/New Horizons/JHAPL

The New Horizons probe revealed the surface features of Pluto in rich detail when it reached the dwarf planet in July 2015. Some of the features look like snapshots of rivers and lakes that are locked firmly in place by Pluto’s frigid temperatures. But now scientists studying the data coming back from New Horizons think that those frozen lakes and rivers could once have been liquid nitrogen.

Pluto has turned out be a surprisingly active place. New Horizons has shown us what might be clouds in Pluto’s atmosphere, mountains that might be ice volcanoes, and cliffs made of methane ice that melt away into the plains. If there were oceans and rivers of liquid nitrogen on the surface of Pluto, that would fit in with our evolving understanding of Pluto as a much more active planet than we thought.

Richard Binzel, a New Horizons team member from MIT, thinks that lakes of liquid nitrogen could have existed some 800 or 900 million years ago. It all stems from Pluto’s axial tilt, which at 120 degrees is much more pronounced than Earth’s relatively mild 23 degree tilt. And computer modelling suggests that this tilt could have even been more extreme many millions of years ago.

The result of this extreme tilt is that much more of Pluto’s surface would have been exposed to sunlight. That may have warmed Pluto enough to allow liquid nitrogen to flow over the planet’s surface. These kinds of changes to a planet’s axial tilt, (and precession and eccentricity) affect a planet’s climate in what are called Milankovitch cycles. The same cycles are thought to have a similar effect on Earth’s climate, though not as extreme as on Pluto.

According to Binzel, Pluto could be somewhere in between its temperature extremes, meaning that if Pluto will ever be warm enough for liquid nitrogen again, it could be hundreds of millions of years from now. “Right now, Pluto is between two extreme climate states,” Binzel says.

Alan Stern is a planetary scientist at the Southwest Research Institute, and New Horizons’ Principal Investigator. He thinks that these long-cycle climate changes could have a very pronounced effect on Pluto, which has a nitrogen-rich atmosphere. In ancient times, Pluto’s atmosphere could have been more dense than Mars’. “This opens up the possibility that liquid nitrogen may have once or even many times flowed on Pluto’s surface,” he said.

More data from New Horizons is still on its way. About half is yet to arrive. That data, and further analysis, might discredit the fledgling idea that Pluto had and will have again lakes of liquid nitrogen. “We are just beginning to understand the long-term climate of Pluto,” said Binzel.

This week is the 47th Lunar and Planetary Science Conference (LPSC) in Houston. Members of the New Horizons team will be presenting almost 40 reports on Pluto and its system of moons at this conference. Stern’s lecture, titled “The Exploration of Pluto,” will be archived online at http://livestream.com/viewnow/LPSC2016.

March 18, 2016April 12, 2016 by Evan Gough

New Horizons Team Releases First Papers On Pluto And Its Moons

This image of Pluto taken by the New Horizons spacecraft shows the blue color of Pluto's high-altitude haze. Image: NASA/New Horizons.

The New Horizons team is releasing their first set of five research papers on Pluto and its moons. What the team is calling a “comprehensive set of papers” is the result of the New Horizons spacecraft’s close encounter with Pluto and its moons last summer. New Horizons has been transmitting data from the encounter that time, and will be sending data back for months to come.

We can tell from images that Pluto is not what we thought it was. Images and data show that Pluto is a much more active planet than we thought, and its surface shows a diversity of landscapes and geological processes. There’s been a lot of discussion about Pluto and its moons, and a lot of educated guesses about what’s going on there, but the 5 papers released by the team will take the discussion to a new level.

“These five detailed papers completely transform our view of Pluto – revealing the former ‘astronomer’s planet’ to be a real world with diverse and active geology, exotic surface chemistry, a complex atmosphere, puzzling interaction with the sun and an intriguing system of small moons,” said Alan Stern, New Horizons principal investigator from the Southwest Research Institute (SwRI), Boulder, Colorado.

The surface of Pluto is a constantly changing palette, shaped by the interactions between the volatile compounds nitrogen, methane, and carbon monoxide ices with the much sturdier and more predictable water ice. The evaporation and condensation of these compounds shapes the surface of Pluto. “These cycles are a lot richer than those on Earth, where there’s really only one material that condenses and evaporates – water,” said Will Grundy of the Lowell Observatory, Flagstaff, Arizona.

Images from New Horizons showed that Pluto’s moons are highly reflective, much more reflective than other bodies in the Kuiper Belt. This led scientists to believe that rather than being captured from the Kuiper Belt and drawn into orbit around Pluto, the moons may have been a result of a collision that formed the Pluto system.

The New Horizons team has found evidence to support this, and evidence that the surface ages of some moons are at least 4 billion years old. “These latter two results reinforce the hypothesis that the small moons formed in the aftermath of a collision that produced the Pluto-Charon binary system,” said Hal Weaver, New Horizons project scientist from the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.

There’s a lot of material in these papers, and I direct interested readers to a summary here: Top New Horizons Findings.

The papers are published in Science.

March 15, 2016March 18, 2016 by Evan Gough

Eat Your Heart Out Pluto

Sublimation of methane ice (shown in purple in the right inset) to methane gas may be eroding the cliffs of Piri Rupes. This process is creating what looks like a bite mark in Pluto's surface, and leaving the Piri Planitia in their wake. (All names for the geographical features on Pluto are still informal.) Image: NASA/JHUAPL/SwRI

Images from the New Horizons spacecraft show a bite-mark shaped feature on the surface of Pluto. Scientists think that the feature is caused by the sublimation of methane ice, causing cliffs to erode and leaving a flat plain in their place. The images were captured just prior to New Horizon’s closest approach to Pluto on July 14th, 2015.

In the image above, which is of Pluto’s western hemisphere, three main features are shown. The first is Vega Terra, which as a raised plateau area. The second is the Piri Planitia, which is a flatter and lower area of plains. Piri Planitia shows an absence of craters, meaning it is geologically younger. Dividing Terra and Planitia are the Piri Rupes, the cliffs which have the bite-mark shaped feature that caught the interest of scientist.

The colored image on the right shows methane-rich areas in purple. Scientists think that as the methane ice of Piri Rupes is sublimated away into the atmosphere, the cliffs are removed and the flat plains of Piri Planitia take their place. The image also shows some methane mesas which have not sublimated away yet.

This image shows the location on Pluto where the sublimation of methane is leaving a bite-mark shape, and changing the surface of Pluto. Image: NASA/JHUAPL/SwRI

New Horizons’ data also shows that Piri Planitia has a higher content of water ice, which is shown in blue. Because of the frigid temperature on Pluto, it’s thought that this water ice is like bedrock. It is immobile, and as the methane ice is sublimated away, the water ice bedrock of Piri Planitia is left exposed.

Prior to New Horizons’ arrival at Pluto, it was generally thought that not much was happening at Pluto. But as these images show, and as New Horizons keeps proving, Pluto is far from an inactive place, and there’s a lot to hold the interest of planetary scientists.

March 11, 2016August 21, 2016 by Matt Williams

Kuiper Belt Objects Point The Way To 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

On January 20th, 2016, researchers Konstantin Batygin and Michael E. Brown of Caltech announced that they had found evidence that hinted at the existence of a massive planet at the edge of the Solar System. Based on mathematical modeling and computer simulations, they predicted that this planet would be a super-Earth, two to four times Earth’s size and 10 times as massive. They also estimated that, given its distance and highly elliptical orbit, it would take 10,000 – 20,000 years to orbit the Sun.

Since that time, many researchers have responded with their own studies about the possible existence of this mysterious “Planet 9”. One of the latest comes from the University of Arizona, where a research team from the Lunar and Planetary Laboratory have indicated that the extreme eccentricity of distant Kuiper Belt Objects (KBOs) might indicate that they crossed paths with a massive planet in the past.

For some time now, it has been understood that there are a few known KBOs who’s dynamics are different than those of other belt objects. Whereas most are significantly controlled by the gravity of the gas giants planets in their current orbits (particularly Neptune), certain members of the scattered disk population of the Kuiper Belt have unusually closely-spaced orbits.

The six most distant known objects in the solar system with orbits exclusively beyond Neptune (magenta), including Sedna (dark magenta), all mysteriously line up in a single direction. Also, when viewed in three dimensions, they tilt nearly identically away from the plane of the solar system. Another population of Kuiper belt objects (cyan) are forced into orbits that are perpendicular to the plane of the solar system and clustered in orientation. Batygin and Brown show that a planet with 10 times the mass of the earth in a distant eccentric orbit (orange) anti-aligned with the magenta orbits and perpendicular to the cyan orbits is required to maintain this configuration. Credit: Caltech/R. Hurt (IPAC) — *The orbits of Neptune (magenta), Sedna (dark magenta), a series of Kuiper belt objects (cyan), and the hypothetical Planet 9 (orange). Credit: Caltech/R. Hurt (IPAC)*

When Batygin and Brown first announced their findings back in January, they indicated that these objects instead appeared to be highly clustered with respect to their perihelion positions and orbital planes. What’s more, their calculation showed that the odds of this being a chance occurrence were extremely low (they calculated a probability of 0.007%).

Instead, they theorized that it was a distant eccentric planet that was responsible for maintaining the orbits of these KBOs. In order to do this, the planet in question would have to be over ten times as massive as Earth, and have an orbit that lay roughly on the same plane (but with a perihelion oriented 180° away from those of the KBOs).

Such a planet not only offered an explanation for the presence of high-perihelion Sedna-like objects – i.e. planetoids that have extremely eccentric orbits around the Sun. It would also help to explain where distant and highly inclined objects in the outer Solar System come from, since their origins have been unclear up until this point.

In a paper titled “Coralling a distant planet with extreme resonant Kuiper belt objects“, the University of Arizona research team – which included Professor Renu Malhotra, Dr. Kathryn Volk, and Xianyu Wang – looked at things from another angle. If in fact Planet 9 were crossing paths with certain high-eccentricity KBOs, they reasoned, it was a good bet that its orbit was in resonance with these objects.

*Pluto and its cohorts in the icy-asteroid-rich Kuiper Belt beyond the orbit of Neptune. Credit: NASA*

To break it down, small bodies are ejected from the Solar System all the time due to encounters with larger objects that perturb their orbits. In order to avoid being ejected, smaller bodies need to be protected by orbital resonances. While the smaller and larger objects may pass within each others’ orbital path, they are never close enough that they would able to exert a significant influence on each other.

This is how Pluto has remained a part of the Solar System, despite having an eccentric orbit that periodically cross Neptune’s path. Though Neptune and Pluto cross each others orbit, they are never close enough to each other that Neptune’s influence would force Pluto out of our Solar System. Using this same reasoning, they hypothesized that the KBOs examined by Batygin and Brown might be in an orbital resonance with the Planet 9.

As Dr. Malhotra, Volk and Wang told Universe Today via email:

“The extreme Kuiper belt objects we investigate in our paper are distinct from the others because they all have very distant, very elliptical orbits, but their closest approach to the Sun isn’t really close enough for them to meaningfully interact with Neptune. So we have these six observed objects whose orbits are currently fairly unaffected by the known planets in our Solar System. But if there’s another, as yet unobserved planet located a few hundred AU from the Sun, these six objects would be affected by that planet.”

After examining the orbital periods of these six KBOs – Sedna, 2010 GB174, 2004 VN112, 2012 VP113, and 2013 GP136 – they concluded that a hypothetical planet with an orbital period of about 17,117 years (or a semimajor axis of about 665 AU), would have the necessary period ratios with these four objects. This would fall within the parameters estimated by Batygin and Brown for the planet’s orbital period (10,000 – 20,000 years).

*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*

Their analysis also offered suggestions as to what kind of resonance the planet has with the KBOs in question. Whereas Sedna’s orbital period would have a 3:2 resonance with the planet, 2010 GB174 would be in a 5:2 resonance, 2994 VN112 in a 3:1, 2004 VP113 in 4:1, and 2013 GP136 in 9:1. These sort of resonances are simply not likely without the presence of a larger planet.

“For a resonance to be dynamically meaningful in the outer Solar System, you need one of the objects to have enough mass to have a reasonably strong gravitational effect on the other,” said the research team. “The extreme Kuiper belt objects aren’t really massive enough to be in resonances with each other, but the fact that their orbital periods fall along simple ratios might mean that they each are in resonance with a massive, unseen object.”

But what is perhaps most exciting is that their findings could help to narrow the range of Planet 9’s possible location. Since each orbital resonance provides a geometric relationship between the bodies involved, the resonant configurations of these KBOs can help point astronomers to the right spot in our Solar System to find it.

But of course, Malhotra and her colleagues freely admit that several unknowns remain, and further observation and study is necessary before Planet 9 can be confirmed:

“There are a lot of uncertainties here. The orbits of these extreme Kuiper belt objects are not very well known because they move very slowly on the sky and we’ve only observed very small portions of their orbital motion. So their orbital periods might differ from the current estimates, which could make some of them not resonant with the hypothetical planet. It could also just be chance that the orbital periods of the objects are related; we haven’t observed very many of these types of objects, so we have a limited set of data to work with.”

Based on a careful study of Saturn's orbit and using mathematical models, French scientists were able to whittle down the search region for Planet Nine to "possible" and "probable" zones. Source: CNRS, Cote d'Azur and Paris observatories. Credit: — Estimates of Planet Nine’s “possible” and “probable” zones. by French scientists based on a careful study of Saturn’s orbit and using mathematical models. Source: CNRS, Cote d’Azur and Paris observatories. Credit: Bob King

Ultimately, astronomers and the rest of us will simply have to wait on further observations and calculations. But in the meantime, I think we can all agree that the possibility of a 9th Planet is certainly an intriguing one! For those who grew up thinking that the Solar System had nine planets, these past few years (where Pluto was demoted and that number fell to eight) have been hard to swallow.

But with the possible confirmation of this Super-Earth at the outer edge of the Solar System, that number could be pushed back up to nine soon enough!

Further Reading: arXiv.org