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
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
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.

Clouds Seen On Pluto For First Time

Recent images sent by NASA's New Horizons spacecraft show possible clouds floating over the frozen landscape including the streaky patch at right. Credit: NASA/JHUAPL/SwR
Recent images sent by NASA's New Horizons spacecraft show possible clouds floating over the frozen landscape including the streaky patch at right. Credit: NASA/JHUAPL/SwR
Recent images sent by NASA’s New Horizons spacecraft show possible clouds floating over the frozen landscape including the hazy streak right of center. Credit: NASA/JHUAPL/SwRI

I think we were all blown away when the New Horizons spacecraft looked back at Pluto’s dark side and returned the first photos of a surprisingly complex, layered atmosphere. Colorless nitrogen along with a small percentage of methane make up Pluto’s air. Layers of haze are likely created when the two gases react in sunlight to form tiny, soot-like particles called tholins. These can ultimately grow large enough to settle toward the surface and coat and color Pluto’s icy exterior.

Close up of the back side of Pluto taken by New Horizons shows multiple layers of haze in its mostly nitrogen atmosphere. Credit:
Close up of the back side of Pluto taken by New Horizons shows multiple layers of haze in its mostly nitrogen atmosphere. Credit: NASA/JHUAPL/SwRI

Now it seems Pluto’s atmosphere is capable of doing even more — making clouds! In an e-mail exchange with New Scientist, Lowell Observatory astronomer Will Grundy discusses the possibility that streaks and small condensations within the hazes might be individual clouds. Grundy also tracked a feature as it passed over different parts of the Plutonian landscape below, strongly suggesting a cloud.  If confirmed, they’d be the first-ever clouds seen on the dwarf planet, and a sign this small 1,473-mile-wide (2,370 km) orb possesses an even more complex atmosphere than imagined.

Faint arrows along Pluto's limb point to possible clouds in a low altitude haze layer. More distinct possible clouds are arrowed at left. Credit: NASA/JHUAPL/SwR
Faint arrows along Pluto’s limb point to possible clouds in a low altitude haze layer. More distinct possible clouds are arrowed at left. Credit: NASA/JHUAPL/SwRI
The smooth expanse of the informally named Sputnik Planum (right) is flanked to the west (left) by rugged mountains up to 11,000 feet (3,500 meters) high, including the informally named Norgay Montes in the foreground and Hillary Montes on the skyline. The backlighting highlights more than a dozen layers of haze in Pluto's tenuous but distended atmosphere.
15 minutes after its closest approach, New Horizons snapped this image of the smooth expanse of Sputnik Planum (right) flanked to the west (left) by rugged mountains up to 11,000 feet (3,500 meters) high, including the informally named Norgay Montes in the foreground and Hillary Montes on the skyline. The backlighting highlights more than a dozen layers of haze in Pluto’s tenuous but distended atmosphere. Credit: NASA/JHUAPL/SwRI

Given the onion-like layers of haze and potential clouds, perhaps we shouldn’t be surprise that it snows on Pluto. The New Horizons team announced the discovery this week of a chain of exotic snowcapped mountains stretching across the dark expanse of the informally named Cthulhu Regio. Cthulhu, pronounced kuh-THU-lu and named for a character in American horror writer H.P. Lovecraft’s books, stretches nearly halfway around Pluto’s equator, starting from the west of the vast nitrogen ice plain, Sputnik Planum. At 1,850 miles (3,000 km) long and 450 miles (750 km) wide, Cthulhu is a bit larger than the state of Alaska. But ever so much colder!

A section of Cthulhu Regio boasts peaks covered in methane frost or snow.
The upper slopes of Cthulhu’s highest peaks are coated with a bright material that contrasts sharply with the dark red color of the surrounding plains. Scientists think it’s methane ice condensed from Pluto’s atmosphere. The far right panel shows the distribution of methane ice on the surface. Credit: NASA/JHUAPL/SwRI

Cthulhu’s red color probably comes from a covering of dark tholins formed when methane interacts with sunlight. But new close-up images reveal that the region’s highest mountains appear coated with a much brighter material. Scientists think it’s methane, condensed as ice onto the peaks from Pluto’s atmosphere.

“That this material coats only the upper slopes of the peaks suggests methane ice may act like water in Earth’s atmosphere, condensing as frost at high altitude,” said John Stansberry, a New Horizons science team member.

Compositional data from the New Horizon’s Ralph/Multispectral Visible Imaging Camera (MVIC), shown in the right panel in the image above, shows that the location of the bright ice on the mountain peaks correlates almost exactly with the distribution of methane ice, shown in false color as purple.

New Horizons still has plenty of images stored on its hard drive, so we’re likely to see more clouds, frosty peaks and gosh-knows-what-else as the probe speeds ever deeper into space while returning daily postcards from its historic encounter.

Spotlight On Pluto’s Frozen Polar Canyons

This enhanced color view Long canyons run vertically across the polar area—part of the informally named Lowell Regio, named for Percival Lowell, who founded Lowell Observatory and initiated the search that led to Pluto’s discovery. The widest of the canyons is about 45 miles (75 kilometers) wide and runs close to the north pole. Roughly parallel subsidiary canyons to the east and west are approximately 6 miles (10 kilometers) wide.
This enhanced color view Long canyons run vertically across the polar area—part of the informally named Lowell Regio, named for Percival Lowell, who founded Lowell Observatory and initiated the search that led to Pluto’s discovery. The widest of the canyons is about 45 miles (75 kilometers) wide and runs close to the north pole. Roughly parallel subsidiary canyons to the east and west are approximately 6 miles (10 kilometers) wide.
This enhanced color view shows long canyons running vertically across Pluto’s north polar region — part of the informally named Lowell Regio, named for Percival Lowell, who founded Lowell Observatory and initiated the search that led to Pluto’s discovery. The widest of the canyons is about 45 miles (75 km) wide and runs close to the north pole. Roughly parallel secondary canyons to the east and west are approximately 6 miles (10 km) wide. Click for a hi-res view. Credit: NASA/JHUAPL/SRI

Pluto’s frozen nitrogen custard “heart” has certainly received its share of attention. Dozens of wide and close-up photos homing on this fascinating region rimmed by mountains and badlands have been relayed back to Earth by NASA’s New Horizons probe after last July’s flyby. For being only 1,473 miles (2,370 km) in diameter, Pluto displays an incredible diversity of landscapes.

Annotated version of Pluto's north polar region.
Annotated version showing sinuous valleys, canyons and depressions and irregular-shaped pits. Credit: NASA/JHUAPL/SRI with additional annotations by the author

This week, the New Horizons team shifted its focus northward, re-releasing an enhanced color image of the north polar area that was originally part of a high-resolution full-disk photograph of Pluto. Inside of the widest canyon, you can trace the sinuous outline of a narrower valley similar in outward appearance to the Moon’s Alpine Valleycut by a narrow, curvy rill that once served as a conduit for lava.

A composite of enhanced color images of Pluto (lower right) and Charon (upper left), taken by NASA's New Horizons spacecraft as it passed through the Pluto system on July 14, 2015. This image highlights the striking differences between Pluto and Charon. The color and brightness of both Pluto and Charon have been processed identically to allow direct comparison of their surface properties, and to highlight the similarity between Charon's polar red terrain and Pluto's equatorial red terrain. Pluto and Charon are shown with approximately correct relative sizes, but their true separation is not to scale.
A composite of enhanced color images of Pluto (lower right) and Charon, taken by NASA’s New Horizons spacecraft on July 14, 2015. This image highlights the striking differences between Pluto and Charon. The color and brightness of both Pluto and Charon have been processed identically to allow direct comparison of their surface properties, and to highlight the similarity between Charon’s polar red terrain and Pluto’s equatorial red terrain. Pluto and Charon are shown with approximately correct relative sizes, but their separation is not to scale. Credit: NASA/JHUAPL/SRI

We see multiple canyons in Pluto’s polar region, their walls broken and degraded compared to canyons seen elsewhere on the planet. Signs that they may be older and made of weaker materials and likely formed in ancient times when Pluto was more tectonically active. Perhaps they’re related to that long-ago dance between Pluto and its largest moon Charon as the two transitioned into their current tidally-locked embrace.

Cropped version showing three, odd-shaped pits that may reflect sinking of Pluto's crust. Credit:
Cropped version with arrows pointing to three, odd-shaped pits that may reflect sinking of Pluto’s crust. Credit: NASA/JHUAPL/SRI

In the lower right corner of the image, check out those funky-shaped pits that resemble the melting outlines of boot prints in the snow. They reach 45 miles (70 km) across and 2.5 miles (4 km) deep and may indicate locations where subsurface ice has melted or sublimated (vaporized) from below, causing the ground to collapse.

Notice the variation in color across the landscape from yellow-orange to pale blue. High elevations show up in a distinctive yellow, not seen elsewhere on Pluto, with lower elevations and latitudes a bluish gray. New Horizons’ infrared measurements show abundant methane ice across the Lowell Region, with relatively little nitrogen ice. The yellow terrains may be older methane deposits that have been more processed by solar UV light than the bluer terrain. The color variations are especially striking in the area of the collapse pits.

The new map shows exposed water ice to be considerably more widespread across Pluto's surface than was previously known - an important discovery.
The new map shows exposed water ice at Pluto to be considerably more widespread across its surface than was previously known. Its greatest concentration lies in the red-hued regions (in visual light) to the west of Tombaugh Regio, the large, heart-shaped feature. Credit: NASA/JHUAPL/SRI

Pluto’s icy riches include not only methane and nitrogen but also water, which forms the planet’s bedrock. NASA poetically refers to the water ice as “the canvas on which (Pluto’s) more volatile ices paint their seasonally changing patterns”. Recent images made in infrared light shows little or no water ice in the informally named places called Sputnik Planum (the left or western region of Pluto’s “heart”) and Lowell Regio. This indicates that at least in these regions, Pluto’s bedrock remains well hidden beneath a thick blanket of other ices such as methane, nitrogen and carbon monoxide.

To delve more deeply into Pluto, visit the NASA’s photojournal archive, where you’ll find 130 photos (and counting!) of the dwarf planet and its satellites.

We Explored Pluto, Now Let’s Explore The Nearest Star!

Artist’s impression of the planet around Alpha Centauri B. Credit: ESO
Artist’s impression of the planet around Alpha Centauri B. Credit: ESO

On July 14th, 2015, the New Horizons space probe made history when it became the first spacecraft to conduct a flyby of the dwarf planet of Pluto. Since that time, it has been making its way through the Kuiper Belt, on its way to joining Voyager 1 and 2 in interstellar space. With this milestone reached, many are wondering where we should send our spacecraft next.

Naturally, there are those who recommend we set our sights on our nearest star – particularly proponents of interstellar travel and exoplanet hunters. In addition to being Earth’s immediate neighbor, there is the possibility of one or more exoplanets in this system. Confirming the existence of exoplanets would be one of the main reasons to go. But more than that, it would be a major accomplishment!

Continue reading “We Explored Pluto, Now Let’s Explore The Nearest Star!”

Your Favorite Planet May Soon Turn Up In The Mail

The Postal Service will showcase some of the more compelling historic, full-disk images of the planets obtained during the last half-century of space exploration. Some show the planets’ “true color” like Earth and Mars — what one might see if traveling through space. Others, such as Venus, use colors to represent and visualize certain features of a planet based in imaging data. Still others (red storms on Uranus) use the near-infrared spectrum to show things that cannot be seen by the human eye. Credits: USPS/Antonio Alcalá © 2016 USPS
The Postal Service will showcase some of the more compelling historic, full-disk images of the planets obtained during the last half-century of space exploration. Some show the planets’ “true color” like Earth and Mars — what one might see if traveling through space. Others, such as Venus, use colors to represent and visualize certain features of a planet based in imaging data. Still others (red storms on Uranus) use the near-infrared spectrum to show things that cannot be seen by the human eye. Credits: USPS/Antonio Alcalá © 2016 USPS
The Postal Service will showcase some of the more compelling historic, full-disk images of the planets obtained during the last half-century of space exploration. Some show the planets’ “true color” like Earth and Mars — what one might see if traveling through space. Others, such as Venus, use colors to represent and visualize certain features of a planet based in imaging data. Still others (red storms on Uranus) use the near-infrared spectrum to show things invisible to the human eye.
Credits: USPS/Antonio Alcalá © 2016 USPS

Whenever I go to the post office to pick up stamps I always ask for the most colorful ones. No dead president heads for me. Mailing letters is a rare thing nowadays — might as well choose something colorful and interesting. How sweet then that we’ll soon be able to pick and stick our favorite planets (and dwarf planet!) on the mail and send them flying off to far places.

The U.S. Postal Service sneak-previewed a new series of stamps earlier this year highlighting NASA’s Planetary Science program, including a do-over of a famous Pluto stamp commemorating the New Horizons’ historic 2015 flyby. Also in the works are eight new colorful Forever stamps featuring NASA images of the planets, a Global Forever stamp dedicated to Earth’s moon and a tribute to 50 years of Star Trek.

Pluto Explored! In 2006, NASA placed a 29-cent 1991 ‘Pluto: Not Yet Explored’ stamp in the New Horizons spacecraft. With the new stamp, the Postal Service recognizes the first reconnaissance of Pluto in 2015 by NASA’s New Horizon mission. The two separate stamps show an artists’ rendering of the New Horizons spacecraft and the spacecraft’s enhanced color image of Pluto taken near closest approach. Credits: USPS/Antonio Alcalá © 2016 USPS
New Horizons Principal Investigator Alan Stern (left), Johns Hopkins University Applied Physics Laboratory (APL) Director Ralph Semmel (center) and New Horizons Co-Investigator Will Grundy Lowell Observatory hold a print of an U.S. stamp with their suggested update since the New Horizons spacecraft has explored Pluto last July. Credit: NASA/Bill Ingalls

The New Horizons team, which placed a 29-cent 1991 “Pluto: Not Yet Explored” stamp on board the New Horizons spacecraft, is thrilled at the updated stamp recognizing the mission.

“The New Horizons project is proud to have such an important honor from the U.S. Postal Service,” said Alan Stern, New Horizons principal investigator from the Southwest Research Institute. “Since the early 1990s the old, ‘Pluto Not Explored’ stamp served as a rallying cry for many who wanted to mount this historic mission of space exploration. Now that NASA’s New Horizons has accomplished that goal, it’s a wonderful feeling to see these new stamps join others commemorating first explorations of the planets.”

Pluto Explored! In 2006, NASA placed a 29-cent 1991 ‘Pluto: Not Yet Explored’ stamp in the New Horizons spacecraft. With the new stamp, the Postal Service recognizes the first reconnaissance of Pluto in 2015 by NASA’s New Horizon mission. The two separate stamps show an artists’ rendering of the New Horizons spacecraft and the spacecraft’s enhanced color image of Pluto taken near closest approach. Credits: USPS/Antonio Alcalá © 2016 USPS
Pluto Explored! In 2006, NASA placed a 29-cent 1991 ‘Pluto: Not Yet Explored’ stamp in the New Horizons spacecraft. With the new stamp, the Postal Service recognizes the first reconnaissance of Pluto in 2015 by NASA’s New Horizon mission. The two separate stamps show an artists’ rendering of the New Horizons spacecraft and the spacecraft’s enhanced color image of Pluto taken near closest approach.
Credits: USPS/Antonio Alcalá © 2016 USPS

In the upcoming planet series, we’re treated to a color-enhanced Mercury taken by MESSENGER highlighting the planet’s varied terrains. Venus appears in all its naked volcanic glory courtesy of the Magellan probe which mapped the planet using cloud-penetrating radar. Like Mercury, it’s also color-enhanced since it’s impossible to see the surface in visual light even from orbit. Earth and Mars were photographed in natural light with orbiting satellites in tow.

Ten of the round Global Forever stamps of the full moon. Issued at the price of $1.20, this Global Forever stamp can be used to mail a one-ounce letter to any country to which First-Class Mail International service is available. Credits: USPS/Greg Breeding under the art direction of William Gicker © 2016 USPS
Ten of the round Global Forever stamps of the Full Moon. Issued at the price of $1.20, this Global Forever stamp can be used to mail a one-ounce letter to any country to which First-Class Mail International service is available.
Credits: USPS/Greg Breeding under the art direction of William Gicker © 2016 USPS

The Hubble Space Telescope photographed Jupiter in infrared light in 2004, capturing a rare triple transit of the moons Ganymede, Io and Callisto. Saturn comes to us from the Cassini probe, still in good health and routinely sending gorgeous images every month of the ringed planet and its moons. Pity the rings had to be trimmed, but it had to be done to keep all the globes close to the same relative size. Hubble took Uranus’ picture in infrared light, while the Neptune close-up was sent by the Voyager 2 spacecraft in 1989.

Celebrating the 50th anniversary of the television premiere, the new Star Trek Forever stamps showcase four digital illustrations inspired by the television program: the Starship Enterprise inside the outline of a Starfleet insignia, the silhouette of a crewman in a transporter, the silhouette of the Enterprise from above and the Enterprise inside the outline of the Vulcan salute. Credits: USPS/Heads of State under the art direction of Antonio Alcalá © 2016 USPS
Celebrating the 50th anniversary of the television premiere, the new Star Trek Forever stamps showcase four digital illustrations inspired by the television program. Credits: USPS/Heads of State under the art direction of Antonio Alcalá © 2016 USPS

2016 also marks the 50th anniversary of the television premier of Star Trek, which the post office will commemorate with the new Star Trek Forever stamps. They feature four digital illustrations inspired by the television program: the Starship Enterprise inside the outline of a Starfleet insignia, the silhouette of a crewman in a transporter, the silhouette of the Enterprise from above and the Enterprise inside the outline of the Vulcan salute.

The Global Moon stamp was issued on Feb. 22. You can pre-order the Pluto and planet stamps from USPS.com 30 days before their dedication between May 28 and June 4 at the World Stamp Show in New York. Expect the Star Trek series sometime this summer.

Astronomers Find Theoretical Evidence for Distant Gas Giant Planet in Our Solar System

Artist's concept of the hypothetical "Planet Nine." Could it have moons? Credit: NASA/JPL-Caltech/Robert Hurt
Artistic rendering shows the distant view from theoretical Planet Nine back towards the sun. The planet is thought to be gaseous, similar to Uranus and Neptune. Hypothetical lightning lights up the night side.  Credit: Caltech/R. Hurt (IPAC)
Artistic rendering shows the distant view from theoretical Planet Nine back towards the sun. The planet is thought to be gaseous, similar to Uranus and Neptune. Hypothetical lightning lights up the night side. Credit: Caltech/R. Hurt (IPAC)

The astronomer known worldwide for vigorously promoting the demotion of Pluto from its decades long perch as the 9th Planet, has now found theoretical evidence for a new and very distant gas giant planet lurking way beyond Pluto out to the far reaches of our solar system.

In an obvious reference to the planethood controversy, the proposed new planet is nicknamed ‘Planet Nine’ and its absolutely huge! Continue reading “Astronomers Find Theoretical Evidence for Distant Gas Giant Planet in Our Solar System”

“X” Marks the Spot of Convective Churning on Hot Pluto

“X” marks the spot in this image transmitted to Earth on Dec. 24, 2015 from the Long Range Reconnaissance Imager (LORRI) from NASA’s New Horizons’ showing the highest-resolution swath of Pluto at the center of Sputnik Planum, the informally named plain that forms the left side of Pluto’s “heart.” The pattern of polygonal cells stems from the slow thermal convection of the nitrogen-dominated ices. Also visible is a a dirty block of water ice “floating” in denser solid nitrogen. Credits: NASA/JHUAPL/SwRI

“X” marks the spot that’s illustrative of “convective churning” resulting from subsurface planetary heating, as seen in a fascinating new super high resolution image received from NASA’s New Horizons spacecraft on Christmas Eve, Dec. 24, 2015. Its situated at the very center of the left ventricle of Pluto’s huge “heart” – an icy flow plain that’s informally named “Sputnik Planum.”

The “X” feature – see image above – is located in an area of intersecting cells, shaped like polygons, on the plains of “Sputnik Planum” which are mostly comprised of frozen nitrogen ices.

Continue reading ““X” Marks the Spot of Convective Churning on Hot Pluto”

Our Highest Resolution Views Yet of Pluto’s Surface

The Mountainous Shoreline of Sputnik Planum on Pluto. Great blocks of Pluto’s water-ice crust appear jammed together in the informally named al-Idrisi mountains. Some mountain sides appear coated in dark material, while other sides are bright. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
The Mountainous Shoreline of Sputnik Planum on Pluto. Great blocks of Pluto’s water-ice crust appear jammed together in the informally named al-Idrisi mountains. Some mountain sides appear coated in dark material, while other sides are bright. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

The New Horizons spacecraft has been slowly sending back all the images and data it gathered during its July flyby of the Pluto system. The latest batch of images to arrive here on Earth contains some of the highest resolution views yet that it captured of Pluto’s surface, taken during the spacecraft’s closest approach.

The images show a wide variety of spectacular craters, mountains and glaciers. The New Horizons team said the images have resolutions of about 250-280 feet (77-85 meters) per pixel – revealing features less than half the size of a city block on the diverse surface of the distant dwarf planet. The images are six times better than the resolution of the global Pluto map New Horizons obtained.
Continue reading “Our Highest Resolution Views Yet of Pluto’s Surface”

New Horizons Takes Closest Image Ever of a Kuiper Belt Object

New Horizons’ Long Range Reconnaissance Imager (LORRI) took this image on Nov. 2, 2015 of a 90-mile (150-kilometer)-wide ancient Kuiper Belt Object named 1994 JR1, moving against a background of stars. Credit: NASA/JHUAPL/SwRI
New Horizons’ Long Range Reconnaissance Imager (LORRI) took this image on Nov. 2, 2015 of a 90-mile (150-kilometer)-wide ancient Kuiper Belt Object named 1994 JR1, moving against a background of stars. Credit: NASA/JHUAPL/SwRI

The New Horizons spacecraft is already 209,437,000 km (130,138,000 miles) past Pluto (as of Dec. 4, 2015), making it 5,226,950,000 km (3,247,880,000 miles) from Earth. So, yes, it’s way out there. Recently, it took the closest images ever of a distant Kuiper Belt object, setting a record by a factor of at least 15, according to NASA. The team says this image demonstrates the spacecraft’s ability to observe numerous similar bodies over the next several years.
Continue reading “New Horizons Takes Closest Image Ever of a Kuiper Belt Object”

See Daytime Views of Pluto and Charon’s Rotation

On approach in July 2015, the cameras on NASA's New Horizons spacecraft captured Pluto rotating over the course of a full "Pluto day." The best available images of each side of Pluto taken during approach have been combined to create this view of a full rotation. Credit: NASA/JHUAPL/SwRI.

A day on Pluto is 6.4 Earth days (6 days 9 hours and 36 minutes) long. That’s a lengthy, cold, and rather dark day. But this new image released by the New Horizons spacecraft team gives us a better idea of what a day on Pluto might be like. This montage of images shows Pluto rotating over the course of a full Pluto day.

It is interesting to note that Pluto’s moon Charon is tidally locked around Pluto, so this means that Charon takes 6.4 Earth days to orbit around Pluto – the same amount of time as a day on Pluto. If you were standing on Pluto, Charon would always be at the same place in the sky, or you wouldn’t be able to see it at all. And vise versa if you were on Charon.

New Horizons also captured a full day rotation for Charon, too, which you can see below.

On approach to the Pluto system in July 2015, the cameras on NASA's New Horizons spacecraft captured images of the largest of Pluto's five moons, Charon, rotating over the course of a full day. The best currently available images of each side of Charon taken during approach have been combined to create this view of a full rotation of the moon. Credit: NASA/JHUAPL/SwRI.
On approach to the Pluto system in July 2015, the cameras on NASA’s New Horizons spacecraft captured images of the largest of Pluto’s five moons, Charon, rotating over the course of a full day. The best currently available images of each side of Charon taken during approach have been combined to create this view of a full rotation of the moon. Credit: NASA/JHUAPL/SwRI.

The images were taken by the Long Range Reconnaissance Imager (LORRI) and the Ralph/Multispectral Visible Imaging Camera as New Horizons zoomed toward the Pluto system, and in the various images the distance between New Horizons and Pluto decreased from 5 million miles (8 million kilometers) on July 7 to 400,000 miles (about 645,000 kilometers) on July 13, 2015.

The science team explained that in the Pluto montage, the more distant images are at the 12 to 3 o’clock position, and so these are the best views we have of the peculiar “bumps” or impact craters on the far side. The side New Horizons saw in most detail – what the mission team calls the “encounter hemisphere” – is at the 6 o’clock position. The most prevalent feature there is the heart-shaped, “Tombaugh Regio” area that made us all love Pluto even more.

The odd shape of Pluto in the 12 and 1 o’clock position images aren’t lumps and deformities, but just artifacts from the way the images were combined to create these composites.

For the Charon montage, the images at the 9 o’clock position were taken from the greatest distance, with few of the signature surface features visible, such as the cratered uplands, canyons, or rolling plains of the region informally named Vulcan Planum. The side New Horizons saw in most detail, during closest approach on July 14, 2015, is at the 12 o’clock position.

As a comparison, below is a timelapse view of the Pluto-Charon orbital dance, which was taken by New Horizons back in January 2015. Pluto and Charon were observed for an entire rotation of each body, the same 6 days 9 hours and 36 minutes.

Pluto and Charon were observed by the New Horizons spacecraft for an entire rotation of each body; a “day” on Pluto and Charon is 6.4, which is  Earth days. The first of the images was taken when New Horizons was about 3 billion miles from Earth, but just 126 million miles (203 million kilometers) from Pluto, on Jan. 25-31, 2015. NASA/APL/Southwest Research Institute.
Pluto and Charon were observed by the New Horizons spacecraft for an entire rotation of each body; a “day” on Pluto and Charon is 6.4, which is Earth days. The first of the images was taken when New Horizons was about 3 billion miles from Earth, but just 126 million miles (203 million kilometers) from Pluto, on Jan. 25-31, 2015. NASA/APL/Southwest Research Institute.

Source: New Horizons