We’ve only had blurry images of Pluto up until New Horizons. So what did we learn when we got up close and personal with Pluto and its moons?
Clyde Tombaugh first discovered Pluto in 1930. He saw only see a single speck of light moving slowly in front of the background stars as he flipped photographic plates back and forth. Sadly, this was the best anyone could do for decades. Even the mighty Hubble, the most sensitive instrument ever focused on Pluto, could only resolve a few grainy pixels.
It’s because Pluto is really really far away: 7.5 billion kilometers. Just the light alone from there takes over 4 hours to reach us. In order to get any more information, humanity needed to reach out and send a spacecraft to Pluto, and photograph it, up close and personal.
In 1989, Alan Stern and a group of planetary scientists began working on a mission. Their work culminated in NASA’s New Horizons spacecraft, launched in 2006, beginning a 9 and a half year journey. And unless you’ve been living in a lunar lava tube, you know that New Horizons finally reached its destination in mid July 2015, passing a narrow 12,472 kilometers above the surface.
For the very first time in human history, we saw a member of the Kuiper Belt right up in it’s business. And now I retire these old low quality images Pluto! Begone artist’s illustrations!
From here on out, we’re all about sick high def photos of the surface and its moons. I for one am going to revel in them for a while.
So fashion shoots aside, what did we actually learn about Pluto? The primary mission was to map the geography of Pluto and its biggest moon, Charon. It would study the surface chemistry of these icy worlds, and measure their atmospheres, if they even exist at all.
The mission had a few other objectives, and of course, planetary scientists knew that the spacecraft would just surprise us with stuff we never expected. Kuiper Belt objects like Pluto and Charon are ancient; geologists expected them to be pockmarked with craters, large and small.
Views of Pluto during New Horizons’ approach. Credit: NASA/Damian Peach
Surprisingly, New Horizons showed relatively smooth surfaces on both worlds. Pluto has a Texas-sized region newly named Sputnik Planum, where exotic ices flow like glaciers. Frozen nitrogen, carbon dioxide and methane ices act just like the ones we have here on Earth. We can see from the relative lack of craters that this process is still happening.
Pluto has mountains. Mountains! Close ups show a young range with peaks as high as 11,000 feet, or 3,500 meters. Here’s the crazy part. Those exotic chemicals that act like snow and ice? They’re not hard enough to make mountain peaks like this.
At extreme cold temperatures, water ice becomes as hard as rock. These mountains are made of ice, and they’re very young, probably less than 100 million years old. There could be plate tectonics on Pluto, but with ice, not rock. My mind is blown.
Pluto’s moon Charon has a huge chasm longer and deeper than the Grand Canyon in Arizona and although scientists hoped to see an atmosphere, the reality was beyond anyone’s expectations.
Backlit by the sun, Pluto’s atmosphere rings its silhouette like a luminous halo in this image taken by NASA’s New Horizons spacecraft around midnight EDT on July 15. This global portrait of the atmosphere was captured when the spacecraft was about 1.25 million miles (2 million kilometers) from Pluto and shows structures as small as 12 miles across. The image, delivered to Earth on July 23, is displayed with north at the top of the frame. Credits: NASA/JHUAPL/SwRI
New Horizons detected a thin nitrogen atmosphere at Pluto. It could be snowing nitrogen on Pluto right now. There could be faint winds, since there are regions on Pluto that look like they might have undergone weathering.
Take a look at this photograph as New Horizons zipped away. You can see the atmosphere clearly surrounding the dwarf planet, interacting with the solar wind and creating a tail that stretches away from the Sun.
Here’s my favorite thing we learned. Pluto is about 80 km larger than previous estimates, which makes it the largest Kuiper Belt Object found so far. Even bigger than Eris, which is still a little more massive. So maybe it’s time to revisit that Pluto planethood debate again. I’m just messing with you. No good will ever come from having that debate. It will only end in tears.
Interestingly, the data connection between Earth and New Horizons is tenuous. Possibly the worst internet since AOL. It can only transmit back about 1kb of data per second, which means that we’ll need to wait about 16 months for the photographs and data to be sent home during the first few days of the flyby.
As an extra bonus, this isn’t the last we’re going to hear from New Horizons. Because it’s so far away, as the spacecraft can only trickle data back to Earth. It’s going to take almost 2 years for all the images and measurements it gathered during its flyby to get back to Earth for scientists to study. Expect many more discoveries and announcements over the coming years, and more videos from us.
Now that Pluto has finally been explored, where do you think we should go next in the Solar System? Tell us in the comments below.
Highest resolution mosaic of ‘Tombaugh Regio’ shows the heart-shaped region on Pluto focusing on ice flows and plains of ‘Sputnik Planum’ at top and icy mountain ranges of ‘Hillary Montes’ and ‘Norgay Montes’ below. This new mosaic combines the seven highest resolution images captured by NASA’s New Horizons LORRI imager during history making closest approach flyby on July 14, 2015. Inset at right shows global view of Pluto with location of mosaic and huge heart-shaped region in context. Annotated with place names. Credit: NASA/JHUAPL/SWRI/ Marco Di Lorenzo/Ken Kremer/kenkremer.com
Highest resolution mosaic of ‘Tombaugh Regio’ shows the heart-shaped region on Pluto focusing on ice flows and plains of ‘Sputnik Planum’ at top and icy mountain ranges of ‘Hillary Montes’ and ‘Norgay Montes’ below. This new mosaic combines the seven highest resolution images captured by NASA’s New Horizons LORRI imager during history making closest approach flyby on July 14, 2015. Inset at right shows global view of Pluto with location of mosaic and huge heart-shaped region in context. Annotated with place names. Credit: NASA/JHUAPL/SWRI/ Marco Di Lorenzo/Ken Kremer/kenkremer.com
Unannotated version below[/caption]
Now the last explored planetary system in our solar system is being revealed for the first time in history to human eyes, piece by piece, in the form of the highest resolution flyover mosaics and movies of the alien surface ever available, now and for decades to come.
With the resoundingly successful close flyby completed and the piano shaped New Horizons probe now looking in the rear view mirror, the scientific booty is raining down on receivers back on Earth. However it will take about 16 months to send all the flyby science data back to Earth due to limited bandwidth.
The first series of seven breathtaking high resolution surface images focusing on Pluto’s bright heart-shaped region, informally named ‘Tombaugh Regio’, has been stitched together into our new and wider view mosaic, shown above and below, by the image processing team of Marco Di Lorenzo and Ken Kremer.
Furthermore the New Horizons team has created a spectacular simulated flyover movie centered in the heart of Pluto’s huge ‘Heart’ at ‘Tombaugh Regio’, showing the stunning views including the incredibly recent ice flows and plains of ‘Sputnik Planum’ and monumental icy mountain ranges of ‘Norgay Montes’ and newly discovered ‘Hillary Montes.’
The mosaic and movie are compiled from the seven highest resolution images captured by NASA’s New Horizons LORRI imager during the history making closest approach flyby.
The LORRI images were taken from a distance of 48,000 miles (77,000 kilometers) from the surface of the planet about 1.5 hours prior to the closest approach at 7:49 a.m. EDT on July 14. The images easily resolve structures smaller than a mile across.
New Horizon’s unveiled Pluto as a surprising vibrant and geologically active “icy world of wonders” as it barreled past the Pluto-Charon double planet system on July 14 at over 31,000 mph (49,600 kph) and collected unprecedented high resolution imagery and spectral measurements of the utterly alien worlds.
This annotated image of the southern region of Sputnik Planum illustrates its complexity, including the polygonal shapes of Pluto’s icy plains, its two mountain ranges, and a region where it appears that ancient, heavily-cratered terrain has been invaded by much newer icy deposits. The large crater highlighted in the image is about 30 miles (50 kilometers) wide, approximately the size of the greater Washington, DC area. Credits: NASA/JHUAPL/SwRI
The newly-discovered mountain range has been informally named Hillary Montes (Hillary Mountains) for Sir Edmund Hillary, who first summited Mount Everest with Tenzing Norgay in 1953. They rise about one mile (1.6 kilometers) above the surrounding plains, similar to the height of the Appalachian Mountains in the United States.
They are located nearby and somewhat north of another mountain range discovered first and named Norgay Montes (Norgay Mountains).
“For many years, we referred to Pluto as the Everest of planetary exploration,” said New Horizons Principal Investigator Alan Stern of the Southwest Research Institute, Boulder, Colorado.
“It’s fitting that the two climbers who first summited Earth’s highest mountain, Edmund Hillary and Tenzing Norgay, now have their names on this new Everest.”
Watch this flyover above Pluto’s icy plains at Sputnik Planum and Hillary Montes:
Video caption: This simulated flyover of two regions on Pluto, northwestern Sputnik Planum (Sputnik Plain) and Hillary Montes (Hillary Mountains), was created from New Horizons close-approach images. Sputnik Planum has been informally named for Earth’s first artificial satellite, launched in 1957. Hillary Montes have been informally named for Sir Edmund Hillary, one of the first two humans to reach the summit of Mount Everest in 1953. The images were acquired by the Long Range Reconnaissance Imager (LORRI) on July 14 from a distance of 48,000 miles (77,000 kilometers). Features as small as one-half mile (1 kilometer) across are visible. Credit: NASA/JHUAPL/SwRI
The LORRI images show “extensive evidence of exotic ices flowing across Pluto’s surface and revealing signs of recent geologic activity, something scientists hoped to find but didn’t expect.”
Sputnik Planum is a Texas-sized plain, which lies on the western, left half of Pluto’s bilobed and bright heart-shaped feature, known as Tombaugh Regio.
The new imagery and spectral evidence from the Ralph instrument appears to show the flow of nitrogen ices in geologically recent times across a vast region. They appear to flow similar to glaciers on Earth. There are also carbon monoxide and methane ices mixed in with the water ices.
“At Pluto’s temperatures of minus-390 degrees Fahrenheit, these ices can flow like a glacier,” said Bill McKinnon, deputy leader of the New Horizons Geology, Geophysics and Imaging team at Washington University in St. Louis.
“In the southernmost region of the heart, adjacent to the dark equatorial region, it appears that ancient, heavily-cratered terrain has been invaded by much newer icy deposits.”
“We see the flow of viscous ice that looks like glacial flow.”
Highest resolution mosaic of ‘Tombaugh Regio’ shows the heart-shaped region on Pluto focusing on ice flows and plains of ‘Sputnik Planum’ at top and icy mountain ranges of ‘Hillary Montes’ and ‘Norgay Montes’ below. This new mosaic combines the seven highest resolution images captured by NASA’s New Horizons LORRI imager during history making closest approach flyby on July 14, 2015. Inset at right shows global view of Pluto with location of mosaic and huge heart-shaped region in context. Credit: NASA/JHUAPL/SWRI/Marco Di Lorenzo/Ken Kremer/kenkremer.com
As of today, July 26, New Horizons is 12 days past the Pluto flyby and already over 15 million kilometers beyond Pluto and continuing its journey into the Kuiper Belt, the third realm of worlds in our solar system.
New Horizons discovered that Pluto is the largest known body beyond Neptune – and thus reigns as the “King of the Kuiper Belt!”
The science team plans to target New Horizons to fly by another smaller Kuiper Belt Object (KBO) as soon as 2018.
Watch for Ken’s continuing coverage of the Pluto flyby. He was onsite reporting live on the flyby and media briefings for Universe Today from the Johns Hopkins University Applied Physics Laboratory (APL), in Laurel, Md.
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
Four images from New Horizons’ Long Range Reconnaissance Imager (LORRI) were combined with color data from the Ralph instrument to create this enhanced color global view of Pluto. (The lower right edge of Pluto in this view currently lacks high-resolution color coverage.) The images, taken when the spacecraft was 280,000 miles (450,000 kilometers) away, show features as small as 1.4 miles (2.2 kilometers), twice the resolution of the single-image view taken on July 13. Credits: NASA/JHUAPL/SwRI
Hi Res mosaic of ‘Tombaugh Regio’ shows the heart-shaped region on Pluto and focuses on icy mountain ranges of ‘Norgay Montes’ and ice plains of ‘Sputnik Planum.’ The new mosaic combines highest resolution imagery captured by NASA’s New Horizons LORRI imager during history making closest approach flyby on July 14, 2015, draped over a wider, lower resolution view of Tombaugh Regio. Inset at left shows possible wind streaks. Inset at right shows global view of Pluto with location of huge heart-shaped region in context. Annotated with place names. Credit: NASA/JHUAPL/SWRI/ Marco Di Lorenzo/Ken Kremer/kenkremer.com
APPLIED PHYSICS LABORATORY, LAUREL, MD – The highest resolution images ever taken of Pluto by humanity’s first spacecraft ever to visit the last planet in our solar system revealed unanticipated new discoveries of ice mountains as tall as the Rockies and vast craterless plains spanning hundreds of miles (kilometers) across – are now shown in our newly created context mosaic (featured above and below) of the heart-shaped ‘Tombaugh Regio’ area that dominates the alien planet’s surface.
This first high resolution surface mosaic was created from a newly unveiled series of black and white images centered in the Heart of Pluto’s huge ‘Heart, including the ice mountains of ‘Sputnik Planum’ and icy plains of ‘Norgay Montes.’
They were captured by New Horizons’ high resolution Long Range Reconnaissance Imager (LORRI) on July 14 as the probe barreled past the Pluto-Charon binary planet system only four days ago on Tuesday, July 14, at over 31,000 mph (49,600 kph).
These highest resolution LORRI images focused on the “Heart of the Heart” of Pluto have now been stitched into a mosaic by the image processing team of Marco Di Lorenzo and Ken Kremer.
Pluto’s bright heart-shaped region has now been informally renamed “Tombaugh Regio,’ announced John Spencer, New Horizons science team co-investigator at the post flyby media briefing on July 15.
The mosaic of Pluto’s ‘Tombaugh Regio’ is based on the initial imagery released so far as of July 17.
This annotated view of a portion of Pluto’s Sputnik Planum (Sputnik Plain), named for Earth’s first artificial satellite, shows an array of enigmatic features. The surface appears to be divided into irregularly shaped segments that are ringed by narrow troughs, some of which contain darker materials. Features that appear to be groups of mounds and fields of small pits are also visible. This image was acquired by the Long Range Reconnaissance Imager (LORRI) on July 14 from a distance of 48,000 miles (77,000 kilometers). Features as small as a half-mile (1 kilometer) across are visible. Credits: NASA/JHUAPL/SWRI
A pair of high resolution LORRI images was aimed at areas now informally named Norgay Montes (Norgay Mountains) and Sputnik Planum (Sputnik Plain).
Norgay Montes is informally named for Tenzing Norgay, one of the first two humans to reach the summit of Mount Everest, along with Sir Edmund Hillary. Sputnik Planum is informally named for Earth’s first artificial satellite launched by the Soviet Union in 1957.
The two LORRI images are draped over a wider, lower resolution view of Tombaugh Regio – in annotated and unannotated versions. This is highest resolution currently available.
To the left of the mosaic are two small inserts showing possible “wind streaks” say the researchers.
To the right of the mosaic is a global view of Pluto showing the location of Tombaugh Regio and also outlined to show the precise location of the high resolution LORRI mosaic.
Hi Res mosaic of ‘Tombaugh Regio’ shows the heart-shaped region on Pluto and focuses on icy mountain ranges of ‘Norgay Montes’ and ice plains of ‘Sputnik Planum.’ The new mosaic combines highest resolution imagery captured by NASA’s New Horizons LORRI imager during history making closest approach flyby on July 14, 2015. Inset at left shows possible wind streaks. Inset at right shows global view of Pluto with location of huge heart-shaped region in context. Credit: NASA/JHUAPL/SWRI/ Marco Di Lorenzo/Ken Kremer/kenkremer.com
The LORRI images were taken from a distance of 48,000 miles (77,000 kilometers) from the surface of the planet about 1.5 hours prior to the closest approach at 7:49 a.m. EDT on July 14. The images easily resolve structures smaller than a mile across.
The frozen region of Norgay Montes is situated north of Pluto’s icy mountain range at Sputnik Planum.
“This terrain is not easy to explain,” said Jeff Moore, leader of the New Horizons Geology, Geophysics and Imaging Team (GGI) at NASA’s Ames Research Center in Moffett Field, California.
“The discovery of vast, craterless, very young plains on Pluto exceeds all pre-flyby expectations.”
“The landscape is astoundingly amazing. There are a few ancient impact craters on Pluto. But other areas like “Tombaugh Regio” show no craters. The landform change processes are occurring into current geologic times.”
“There are no impact craters in a frozen area north of Pluto’s icy mountains we are now informally calling ‘Sputnik Planum’ after Earth’s first artificial satellite.”
New close-up images of a region near Pluto’s equator reveal a giant surprise — a range of youthful mountains rising as high as 11,000 feet (3,500 meters) above the surface of the icy body. Credits: NASA/JHU APL/SwRI
‘Sputnik Planum’ is composed of a broken surface of irregularly-shaped segments. The polygonal shaped areas are roughly 12 miles (20 kilometers) across, bordered by what appear to be shallow troughs based on a quick look at the data.
The mountain ranges height rival those of the Rockies, says Moore.
The new LORRI close-ups show the icy mountain range has peaks jutting as high as 11,000 feet (3,500 meters) above the surface, announced John Spencer, New Horizons science team co-investigator at the media briefing.
“It’s a very young surface, probably formed less than 100 million years old,’ said Spencer. “It may be active now.”
New Horizons science team co-investigator John Spencer examines print of the newest Pluto image taken on July 13, 2015 after the successful Pluto flyby. Credit: Ken Kremer/kenkremer.com
“Judging from the absence of impact craters, it’s clear that Sputnik Planum couldn’t possibly be more than 100 million years old, and possibly is still being shaped to this day by geologic processes,” noted Moore. “This could be only a week old for all we know.”
During the fast flyby encounter, the New Horizons spacecraft pointed its suite of seven science instruments exclusively on all the bodies in the Pluto system, to maximize the capture of scientific data, as quickly as possible, and store it onto its two solid state digital recorders for later playback.
A major challenge for the mission is the rather slow “downlink” transmission of data back to Mission Control on Earth. Since the average “downlink” is only about 2 kilobits per second via its two transmitters, it will take about 16 months to send all the flyby data back to Earth.
Therefore the team has carefully selected just a few of the highest resolution images and other key instrument data for quick playback. The remaining flyby data will be prioritized for streaming.
“Over 50 gigabits of data were collected during the encounter and flyby periods,” New Horizons principal investigator Alan Stern of the Southwest Research Institute, Boulder, Colorado, said during the July 17 media briefing.
“So far less than 1 gigabit of data has been returned.”
New Horizons 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.
If the spacecraft remains healthy as expected, the science team plans to target New Horizons to fly by another smaller Kuiper Belt Object (KBO) as soon as 2018.
Pluto Explored at Last. The New Horizons mission team celebrates successful flyby of Pluto in the moments after closest approach at 7:49 a.m. EDT on July 14, 2015. New Horizons Principal Investigator Alan Stern of Southwest Research Institute (SwRI), Boulder, CO., left, Johns Hopkins University Applied Physics Laboratory (APL) Director Ralph Semmel, center, and New Horizons Co-Investigator Will Grundy Lowell Observatory hold an enlarged print of an U.S. stamp with their suggested update after Pluto became the final planet in our solar system to be explored by an American space probe (crossing out the words ‘not yet’) – at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. Credit: Ken Kremer/kenkremer.com
Watch for Ken’s continuing coverage of the Pluto flyby. He was onsite reporting live on the flyby and media briefings for Universe Today from the Johns Hopkins University Applied Physics Laboratory (APL), in Laurel, Md.
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
NASA Associate Administrator for the Science Mission Directorate John Grunsfeld, left, New Horizons Principal Investigator Alan Stern of Southwest Research Institute (SwRI), Boulder, CO, second from left, New Horizons Mission Operations Manager Alice Bowman of the Johns Hopkins University Applied Physics Laboratory (APL), second from right, and New Horizons Project Manager Glen Fountain of APL, right, are seen at the conclusion of a press conference after the team received confirmation from the spacecraft that it has completed the flyby of Pluto, Tuesday, July 14, 2015 at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. Credit: Ken Kremer/kenkremer.com
This annotated view of a portion of Pluto’s Sputnik Planum (Sputnik Plain), named for Earth’s first artificial satellite, shows an array of enigmatic features. The surface appears to be divided into irregularly shaped segments that are ringed by narrow troughs, some of which contain darker materials. Features that appear to be groups of mounds and fields of small pits are also visible. This image was acquired by the Long Range Reconnaissance Imager (LORRI) on July 14 from a distance of 48,000 miles (77,000 kilometers). Features as small as a half-mile (1 kilometer) across are visible. Credits: NASA/JHUAPL/SWRI
This annotated view of a portion of Pluto’s Sputnik Planum (Sputnik Plain), named for Earth’s first artificial satellite, shows an array of enigmatic features. The surface appears to be divided into irregularly shaped segments that are ringed by narrow troughs, some of which contain darker materials. Features that appear to be groups of mounds and fields of small pits are also visible. This image was acquired by the Long Range Reconnaissance Imager (LORRI) on July 14 from a distance of 48,000 miles (77,000 kilometers). Features as small as a half-mile (1 kilometer) across are visible. Credits: NASA/JHUAPL/SWRI
See 3 image mosaic below[/caption]
The jaw dropping new imagery of young plains of water ice was publicly released today, July 17, by NASA and scientists leading the New Horizons mission during a media briefing, and has already resulted in ground breaking new scientific discoveries at the last planet in our solar system to be visited by a spacecraft from Earth.
“We have now visited every planet in our solar system with American spacecraft,” said NASA Administrator Charles Bolden. “These findings are already causing us to rethink the dynamics of interior geologic processes.”
New data and dazzling imagery are now from streaming back some 3 billion miles across interplanetary space to mission control on Earth and researchers eagerly awaiting the fruits of more than two decades of hard labor to get to this once-in-a-lifetime opportunity.
“I can’t wait for the new discoveries!” exclaimed Bolden at today’s media briefing.
“Over 50 gigabits of data were collected during the encounter and flyby periods,” New Horizons principal investigator Alan Stern of the Southwest Research Institute, Boulder, Colorado, said during the media briefing.
“So far less than 1 gigabit of data has been returned.”
It will take some 16 months for all the Pluto flyby data to be transmitted back to Earth.
And the team has not been disappointed because the results so far shows Pluto to possess tremendously varied terrain that “far exceed our expectations.”
Video Caption: In the center left of Pluto’s vast heart-shaped feature – informally named “Tombaugh Regio” – lies a vast, craterless plain that appears to be no more than 100 million years old, and is possibly still being shaped by geologic processes. This frozen region is north of Pluto’s icy mountains and has been informally named Sputnik Planum (Sputnik Plain), after Earth’s first artificial satellite. Credits: NASA/JHUAPL/SWRI
Two new high resolution images captured by the probes Long Range Reconnaissance Imager (LORRI) on July 14 were released today and taken from a distance of 48,000 miles (77,000 kilometers). Features as small as one-half mile (1 kilometer) across are visible in the images – shown above and below.
They were snapped from frozen region lying north of Pluto’s icy mountains, in the center-left of the heart feature, informally named “Tombaugh Regio” (Tombaugh Region) after Clyde Tombaugh, who discovered Pluto in 1930.
“This terrain is not easy to explain,” said Jeff Moore, leader of the New Horizons Geology, Geophysics and Imaging Team (GGI) at NASA’s Ames Research Center in Moffett Field, California.
“The discovery of vast, craterless, very young plains on Pluto exceeds all pre-flyby expectations.”
“The landscape is astounding. There are a few ancient impact craters on Pluto. But other areas like “Tombaugh Regio” show no craters. The landform change processes are occurring into current geologic times.”
“There are no impact craters in a frozen area north of Pluto’s icy mountains we are now informally calling ‘Sputnik Planum’ after Earth’s first artificial satellite.”
‘Sputnik Planum’ is composed of a broken surface of irregularly-shaped segments. The polygonal shaped areas are roughly 12 miles (20 kilometers) across, bordered by what appear to be shallow troughs based on a quick look at the data.
Notably, some of the clumps are filled with mysterious darker material. Hills are also visible in some areas, which may have been pushed up. Etched areas on the surface may have been formed by sublimation process where the water ice turns directly from the solid to the gas phase due to the extremely negligible atmosphere pressure.
In some places there are also streaks that may have formed from windblown processes and pitted areas.
Three image mosaic of ‘Tombaugh Regio,’ Pluto’s heart-shaped region, combining highest resolution imagery captured by NASA’s New Horizons LORRI imager during closest approach flyby on July 14, 2015. Credits: NASA/JHUAPL/SWRI. Additional processing Ken Kremer/Marco Di Lorenzo
“It’s just pure coincidence that we got the highest resolution data at Sputnik Planum which is of the most interest scientifically,” Moore noted.
Moore indicated that the team is working on a pair of theories as to how these polygonal segments were formed.
“The irregular shapes may be the result of the contraction of surface materials, similar to what happens when mud dries. Alternatively, they may be a product of convection, similar to wax rising in a lava lamp. On Pluto, convection would occur within a surface layer of frozen carbon monoxide, methane and nitrogen, driven by the scant warmth of Pluto’s interior,” Moore explained.
Pluto’s polygons look remarkably similar to the Martian polygons upon which NASA’s Phoenix lander touched down on in 2008 and dug into. Perhaps they were formed by similar mechanisms or difference ones, contraction or convection, Moore told me during the briefing.
As of yesterday, New Horizons spacecraft completed and exited the Pluto encounter phase, said Stern. “We are now collecting departure science.”
New Horizons is already over 3 million miles beyond Pluto and heading to its next yet to be determined target in the Kuiper Belt.
“With the flyby in the rearview mirror, a decade-long journey to Pluto is over –but, the science payoff is only beginning,” said Jim Green, director of Planetary Science at NASA Headquarters in Washington.
“Data from New Horizons will continue to fuel discovery for years to come.”
Counting down to less than 3 minutes from New Horizons closest approach to Pluto, Jim Green, NASA Planetary Science Division Director, addresses the team, guests and media on Tuesday, July 14, 2015 at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. Credit: Ken Kremer/kenkremer.com
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
Pluto Explored at Last
The New Horizons mission team celebrates successful flyby of Pluto in the moments after closest approach at 7:49 a.m. EDT on July 14, 2015. New Horizons Principal Investigator Alan Stern of Southwest Research Institute (SwRI), Boulder, CO., left, Johns Hopkins University Applied Physics Laboratory (APL) Director Ralph Semmel, center, and New Horizons Co-Investigator Will Grundy Lowell Observatory hold an enlarged print of an U.S. stamp with their suggested update after Pluto became the final planet in our solar system to be explored by an American space probe (crossing out the words ‘not yet’) – at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. Credit: Ken Kremer/kenkremer.comIn the center left of Pluto’s vast heart-shaped feature – informally named “Tombaugh Regio” – lies a vast, craterless plain that appears to be no more than 100 million years old, and is possibly still being shaped by geologic processes. This frozen region is north of Pluto’s icy mountains and has been informally named Sputnik Planum (Sputnik Plain), after Earth’s first artificial satellite. The surface appears to be divided into irregularly-shaped segments that are ringed by narrow troughs. Features that appear to be groups of mounds and fields of small pits are also visible. This image was acquired by the Long Range Reconnaissance Imager (LORRI) on July 14 from a distance of 48,000 miles (77,000 kilometers). Features as small as one-half mile (1 kilometer) across are visible. Credits: NASA/JHUAPL/SWRI
A portrait from the final approach. Pluto and Charon display striking color and brightness contrast in this composite image from July 11, showing high-resolution black-and-white LORRI images colorized with Ralph data collected from the last rotation of Pluto. Color data being returned by the spacecraft now will update these images, bringing color contrast into sharper focus. Credits: NASA-JHUAPL-SWRI
Measurements by New Horizons gathered just in the past few days as the spacecraft barrels towards the Pluto planetary system now confirm that Pluto is indeed the biggest object in the vast region beyond the orbit of Neptune known as the Kuiper Belt.
Pluto is thus the undisputed King of the Kuiper Belt!
Pluto measures 1,473 miles (2,370 kilometers) in diameter, which is at the higher end of the range of previous estimates.
The big news was announced today, by New Horizons principal investigator Alan Stern of the Southwest Research Institute, Boulder, Colorado, during a live media briefing at Pluto mission control at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland.
“This settles the debate about the largest object in the Kuiper Belt,” Stern noted.
New Horizons will 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 during closest approach at approximately 7:49 a.m. EDT (11:49 UTC) on July 14.
The new and definitive measurement of Pluto’s size is based on images taken by the high resolution Long Range Reconnaissance Imager (LORRI) to make this determination.
“The size of Pluto has been debated since its discovery in 1930. We are excited to finally lay this question to rest,” said mission scientist Bill McKinnon, Washington University, St. Louis.
Pluto was the first planet discovered by an American, Clyde Tombaugh.
Pluto’s “Heart” is seen in this new image from New Horizons’ Long Range Reconnaissance Imager (LORRI) received on July 8, 2015 after normal science operations resumed following the scary July 4 safe mode anomaly that briefing shut down all science operations. The LORRI image has been combined with lower-resolution color information from the Ralph instrument. Credits: NASA-JHUAPL-SWRI
Pluto is bigger than Eris, another big Kuiper Belt object discovered in 2005 by Mike Brown of Caltech, which is much further out from the Sun than Pluto. The discovery of Eris further fueled the controversial debate about the status of Pluto’s planethood.
Eris comes in second in size in the Kuiper Belt at only 1,445 miles (2,326 km) in diameter.
On July 11, 2015, New Horizons captured a world that is growing more fascinating by the day. For the first time on Pluto, this view reveals linear features that may be cliffs, as well as a circular feature that could be an impact crater. Rotating into view is the bright heart-shaped feature that will be seen in more detail during New Horizons’ closest approach on July 14. The annotated version includes a diagram indicating Pluto’s north pole, equator, and central meridian. Credits: NASA/JHUAPL/SWRI
Stern also noted that because Pluto is slight bigger than the average of previous estimates, its density is slightly lower than previously thought. Therefore the fraction of ice in its interior is slightly higher and the fraction of rock is slightly lower. But further data is required to pin the density down more precisely.
The uncertainty in Pluto’s size has persisted for decades and was due to the fact that Pluto has a very tenuous atmosphere composed of nitrogen.
Furthermore Pluto’s lowest atmospheric layer called the troposphere, is shallower than previously believed.
On the other hand, its largest moon Charon with which it forms a double planet, lacks a substantial atmosphere and its size was known with near certainty based on ground-based telescopic observation.
New Horizons LORRI imagery has confirmed that Charon measures 751 miles (1208 km) kilometers) across.
Stern also confirmed that frigid Pluto also has a polar cap composed of methane and nitrogen ices based on measurements from the Alice instrument.
LORRI has also zoomed in on two of Pluto’s smaller moons, Nix and Hydra.
“We knew from the time we designed our flyby that we would only be able to study the small moons in detail for just a few days before closest approach,” said Stern. “Now, deep inside Pluto’s sphere of influence, that time has come.”
The approximate sizes of Pluto’s moons Nix and Hydra compared to Denver, Colorado. While Nix and Hydra are illustrated as circles in this diagram, mission scientists anticipate that future observations by New Horizons will show that they are irregular in shape. Credits: JHUAPL/Google
But because they are so small, accurate measurement with LORRI could only be made in the final week prior to the July 14 flyby.
Nix is estimated to be about 20 miles (about 35 kilometers) across, while Hydra is roughly 30 miles (roughly 45 kilometers) across. These sizes lead mission scientists to conclude that their surfaces are quite bright, possibly due to the presence of ice.
Determinations about Pluto’s two smallest moons, Kerberos and Styx, will be made later at some point during the 16-month long playback of data after the July 14 encounter.
It has been three decades since we last visited planetary bodies at the outer reaches of our solar system when Voyager 2 flew past Uranus and Neptune in 1986 and 1989.
New Horizons’ last look at Pluto’s Charon-facing hemisphere reveals the highest resolution view of four intriguing darks spots for decades to come. This image, taken early the morning of July 11, 2015, shows newly-resolved linear features above the equatorial region that intersect, suggestive of polygonal shapes. This image was captured when the spacecraft was 2.5 million miles (4 million kilometers) from Pluto. Credit: NASA/JHUAPL/SWRI
New Horizons is closing in fast on its quarry at a whopping 31,000 mph (49,600 kph) after a nine year interplanetary voyage and is now less than half a million miles away, in the final hours before closest approach.
The New Frontiers spacecraft was built by a team led by Stern and included researchers from SwRI and the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. APL also operates the New Horizons spacecraft and manages the mission.
Watch for Ken’s continuing onsite coverage of the Pluto flyby on July 14 from the Johns Hopkins University Applied Physics Laboratory (APL).
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
Graphic showing New Horizons' busy schedule before and during the flyby. Credit: NASA
Countdown to discovery! Not since Voyager 2’s flyby of Neptune in 1989 have we flung a probe into the frozen outskirts of the Solar System. Speeding along at 30,800 miles per hour New Horizons will pierce the Pluto system like a smartly aimed arrow.
Newest view of Pluto seen from New Horizons on July 11, 2015 shows a world that continues to grow more fascinating and look stranger every day. See annotated version below. Credits: NASA/JHUAPL/SWRIFor the first time on Pluto, this view reveals linear features that may be cliffs, as well as a circular feature that could be an impact crater. Rotating into view is the bright heart-shaped feature that will be seen in more detail during New Horizons’ closest approach on July 14. The annotated version includes a diagram indicating Pluto’s north pole, equator, and central meridian. Credits: NASA/JHUAPL/SWRI
Edging within 7,800 miles of its surface at 7:49 a.m. EDT, the spacecraft’s long-range telescopic camera will resolve features as small as 230 feet (70 meters). Fourteen minutes later, it will zip within 17,930 miles of Charon as well as image Pluto’s four smaller satellites — Hydra, Styx, Nix and Kerberos.
This image shows New Horizons’ current position (3 p.m. EDT July 12) along its planned Pluto flyby trajectory. The green segment of the line shows where New Horizons has traveled; the red indicates the spacecraft’s future path. The Pluto system is tilted on end because the planet’s axis is tipped 123° to the plane of its orbit. Credit: NASA/JHUAPL/SWRI
After zooming past, the craft will turn to photograph Pluto eclipsing the Sun as it looks for the faint glow of rings or dust sheets illuminated by backlight. At the same time, sunlight reflecting off Charon will faintly illuminate Pluto’s backside. What could be more romantic than Charonshine?
Six other science instruments will build thermal maps of the Pluto-Charon pair, measure the composition of the surface and atmosphere and observe Pluto’s interaction with the solar wind. All of this will happen autopilot. It has to. There’s just no time to send a change instructions because of the nearly 9-hour lag in round-trip communications between Earth and probe.
Instruments New Horizons will use to characterize Pluto are REX (atmospheric composition and temperature); PEPSSI (composition of plasma escaping Pluto’s atmosphere); SWAP (solar wind studies); LORRI (close up camera for mapping, geological data); Star Dust Counter (student experiment measuring space dust during the voyage); Ralph (visible and IR imager/spectrometer for surface composition and thermal maps) and Alice (composition of atmosphere and search for atmosphere around Charon). Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Want to go along for the ride? Download and install NASA’s interactive app Eyes on Pluto and then click the launch button on the website. You’ll be shown several options including a live view and preview. Click preview and sit back to watch the next few days of the mission unfold before your eyes.
American astronomer Clyde Tombaugh discovered Pluto in 1930 from Lowell Observatory. Tombaugh died in 1997, but an ounce of his ashes, affixed to the spacecraft in a 2-inch aluminum container. “Interned herein are remains of American Clyde W. Tombaugh, discoverer of Pluto and the solar system’s ‘third zone.’ Adelle and Muron’s boy, Patricia’s husband, Annette and Alden’s father, astronomer, teacher, punster, and friend: Clyde Tombaugh (1906-1997)”
Like me, you’ve probably wondered how daylight on Pluto compares to that on Earth. From 3 billion miles away, the Sun’s too small to see as a disk with the naked eye but still wildly bright. With NASA’s Pluto Time, select your city on an interactive mapand get the time of day when the two are equal. For my city, daylight on Pluto equals the gentle light of early evening twilight six minutes after sunset. An ideal time for walking, but step lightly. In Pluto’s gentle gravity, you only weigh 1/15 as much as on Earth.
Pluto and its inclined orbit are highlighted among the hundreds of thousands of icy asteroids in the Kuiper Belt beyond Neptune. Credit: NASA
New Horizons is the first mission to the Kuiper Belt, a gigantic zone of icy bodies and mysterious small objects orbiting beyond Neptune. This region also is known as the “third” zone of our solar system, beyond the inner rocky planets and outer gas giants. Pluto is its most famous member, though not necessarily the largest. Eris, first observed in 2003, is nearly identical in size. It’s estimated there are hundreds of thousands of icy asteroids larger than 61 miles (100 km) across along with a trillion comets in the Belt, which begins at 30 a.u. (30 times Earth’s distance from the Sun) and reaches to 55 a.u.
During its fleeting flyby, New Horizons will slice across the Pluto system, turning this way and that to photograph and gather data on everything it can. Crucial occultations are shown that will be used to determine the structure and composition of Pluto’s (and possibly Charon’s) atmosphere. Sunlight reflected from Charon will also faintly illuminate Pluto’s backside. Credit: NASA with additions by the author
Below you’ll find a schedule of events in Eastern Time. (Subtract one hour for Central, 2 hours for Mountain and 3 hours for Pacific). Keep in mind the probe will be busy shooting photos and gathering data during the flyby, so we’ll have to wait until Wednesday July 15 to see the the detailed close ups of Pluto and its moons. Even then, New Horizons’ recorders will be so jammed with data and images, it’ll take months to beam it all back to Earth.
A new photo of Charon, too! Chasms, craters, and a dark north polar region are revealed in this image of Pluto’s largest moon taken by New Horizons on July 11, 2015. The annotated version includes a diagram showing Charon’s north pole, equator, and central meridian, with the features highlighted. The prominent crater is about 60 miles (96 km) across; the chasms appear to be geological faults. Credits: NASA/JHUAPL/SWRI
Fasten your seat belts — we’re in for an exciting ride.
We’ll be reporting on results and sharing photos from the flyby here at Universe Today, but you’ll also want to check out NASA’s live coverage on NASA TV, its website and social media.
Monday, July 13
10:30 a.m. to noon – Media briefing on mission status and what to expect broadcast live on NASA TV
Tuesday, July 14
7:30 to 8 a.m. – Arrival at Pluto! Countdown program on NASA TV
At approximately 7:49 a.m., New Horizons is scheduled to be as close as the spacecraft will get to Pluto, approximately 7,800 miles (12,500 km) above the surface, after a journey of more than 9 years and 3 billion miles. For much of the day, New Horizons will be out of communication with mission control as it gathers data about Pluto and its moons.
The moment of closest approach will be marked during a live NASA TV broadcast that includes a countdown and discussion of what’s expected next as New Horizons makes its way past Pluto and potentially dangerous debris.
8 to 9 a.m. – Media briefing, image release on NASA TV
Wednesday, July 15
3 to 4 p.m. – Media Briefing: Seeing Pluto in a New Light; live on NASA TV and release of close-up images of Pluto’s surface and moons, along with initial science team reactions.
We’ll have the latest Pluto photos for you, but you can also check these excellent sites:
ILLUSTRATION IS RESERVED - DO NOT USE. The eight planets of the Solar System and the dwarf planet Pluto. For many astronomers and planetary scientists Pluto's status remains an open question. Redefining what is a planet could return Pluto to the fold - 9 planets and also open the door for many more. Insets from upper left, clockwise: Clyde Tombaugh, Mike Brown, Alan Stern, Gerard Kuiper.(Credit: NASA, Judy Schmidt, Björn Jónsson)
A storm is brewing, a battle of words and a war of the worlds. The Earth is not at risk. It is mostly a civil dispute, but it has the potential to influence the path of careers. In 2014, a Harvard led debate was undertaken on the question: Is Pluto a planet. The impact of the definition of planet and everything else is far reaching – to the ends of the Universe.
It could mean a count of trillions of planets in our galaxy alone or it means leaving the planet Pluto out of the count – designation, just a dwarf planet. This is a question of how to classify non-stellar objects. What is a planet, asteroid, comet, planetoid or dwarf planet? Does our Solar System have 8 planets or some other number? Even the count of planets in our Milky Way galaxy is at stake.
“Dawn arising.” The latest image of Ceres – February 12, 2015 – by the Dawn spacecraft from 80,000 km. With icy deposits pock marking its surface, a possible reservoir of water below its surface, is Ceres a planet, dwarf planet, an asteroid or all three? (Credit: NASA/Dawn)
Not to dwell on the Harvard debate, let it be known that if given their way, the debates outcome would reset the Solar System to nine planets. For over eight years, the solar system has had eight planets. During the period 1807 to 1845, our Solar System had eleven planets. Neptune was discovered in 1846 and astronomers began to discover many more asteroids. They were eliminated from the club. This is very similar to what is now happening to Pluto-like objects – Plutoids. So from 1846 to 1930, there were 8 planets – the ones as defined today.
The discoverer of Pluto – Clyde Tombaugh in the 1930s and again with homebuilt telescope in the 1990s that earned him an assignment at Lowell Observatory – discover Planet X. The cremated remains of Clyde are attached to the New Horizons space probe that is now approaching the dwarf planet Pluto.
In 1930, a Kansas farm boy, Clyde Tombaugh, hired by Lowell Observatory discovered Pluto and for 76 years there were 9 planets. In the year 2006, the International Astronomical Union (IAU) took up a debate using a “democratic process” to accept a new definition of planet, define a new type – dwarf planet and then set everything else as “Small Bodies.” If your head is spinning with planets, you are not alone.
All two body systems have a barycenter, the shared point in space around which they orbit. Pluto and Charon’s happens to be between both bodies due to their proximity and similar mass. (Credit: NASA/New Horizons)
Two NASA missions were launched immediately before and after the IAU announcement took affect. The Dawn mission suddenly was to be launched to an asteroid and a dwarf planet and the New Horizons had rather embarked on a nine year journey to a planet belittled to a dwarf planet – Pluto. Principal Investigator, Dr. Alan Stern was upset. Furthermore, from the discoveries of the Kuiper mission and other discoveries, we now know that there are hundreds of billions of planets in our Milky Way galaxy; possibly trillions. The present definition excludes hundreds of billions of bodies from planethood status.
The presently known largest trans-Neptunian objects (TSO) – are likely to be surpassed by future discoveries. Which of these trans-Neptunian objects (TSO) would you call planets and which “dwarf planets”? (Illustration Credit: Larry McNish, Data: M.Brown)
There are two main camps with de facto leaders. One camp has Dr. Mike Brown of Caltech and the other, Dr. Stern of the Southwest Research Institute (SWRI) as leading figures. A primary focus of Dr. Brown’s research is the study of trans-Neptunian objects while Dr. Sterns’s activities are many but specifically, the New Horizons mission which is 6 months away from its flyby of Pluto. Consider first the IAU Resolution 5A that its members approved:
(1) A “planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.
(2) A “dwarf planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape2, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
(3) All other objects, except satellites, orbiting the Sun shall be referred to collectively as “Small Solar System Bodies”.
This is our starting point – planet, dwarf planet, everything else. Consider “everything else”. This broad category includes meteoroids, asteroids, comets and planetesimals. Perhaps other small body types will arise as we look more closely at the Universe. Within the category, there is now a question of what is an asteroid and what is a comet. NASA’s flybys of comets and now ESA’s Rosetta at 67P/Churyumov–Gerasimenko are making the delineation between the two types difficult. The difference between a meteoroid and an asteroid is simply defined as less than or greater than one meter in size, respectively. So the Chelyabinsk event absolutely involved a small asteroid – about 20 meters in diameter. Planetesimals are small bodies in a solar nebula that are the building blocks of planets but they could lead to the creation of all the other types of small bodies.
Dr. Alan Stern, project scientist for New Horizons and Neil deGrasse Tyson discuss the New Horizons spacecraft in the mission operations center at JHU/APL. The interview was for a NOVA special (12/14/2011), the Pluto Files, about a Kansas farm boy, a missing planet and the 70 years of astronomical discoveries leading to the present day. (Credit: JHU/APL,PBS)
Putting aside the question of “Small Bodies” and its sub-classes, what should be the definition of planet and dwarf planet? These are the two terms that demoted Pluto and raised Ceres to dwarf planet. It is also interesting to note how Resolution 5A is meant exclusively for our Solar System. In 2006, there were not thousands of exo-planets but just a few dozen extreme cases but nevertheless, the IAU did not choose to extend the definition to “stars” but rather just in reference to our pretty well known star, the Sun.
Recall Tim Allen’s movie, “The Santa Clause”. Clauses can cause a heap of trouble. The IAU has such a clause – Clause C which has caused much of the present controversy around the definition of planets. Clause (c) of Resolution 5A: “has cleared the neighborhood around its orbit.” This is the Pluto killer-clause which demoted it to dwarf planet status and reduced the number of planets in our solar system to eight. In a sense, the IAU chose to cauterize a wound, a weakness in the definitions, that if left unchanged, would have led to who knows how many planets in our Solar System.
The question of what is Pluto is open for public discussion so armed with enough knowledge to be dangerous, the following is my proposed alternative to the IAU’s that are arguably an improvement. The present challenge to Pluto’s status lies in the Kuiper Belt and Oort Cloud. Such belts or clouds are probably not uncommon throughout the galaxy. Plutoids are the 500 lb gorilla in the room.
Two spacecraft, Dawn and New Horizon will reach their final objectives in 2015 – Dwarf Planets – Ceres and Pluto. (Credit: NASA, Illustration – T.Reyes)
This year, as touted by the likes of Planetary Society, Universe Today and elsewhere, is the year of the dwarf planet. How remarkable and surprising will the study of Ceres, Pluto and Charon by NASA spacecraft be? There is a strong possibility that after the celestial dust clears and data analysis is published, the IAU will take on the challenge again to better define what is a planet and everything else. It is impossible to imagine that the definitions can remain unchanged for long. Even now, there is sufficient information to independently assess the definitions and weigh in on the approaching debate. Anyone or any group – from grade schools to astronomical societies – can take on the challenge.
To encourage a debate and educate the public on the incredible universe that space probes and advanced telescopes are revealing, what follows is one proposed solution to what is a planet and everything else.
planet: is a celestial body that a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium – nearly round shape, b) has a differentiated interior as a result of its formation c) has insufficient mass to fuse hydrogen in its core, d) does not match the definition of a moon.
minor planet: is a planet with a mass less than one Pluto mass and does not match the definition of a moon.
inter-Stellar (minor) planet: is a (minor) planet that is not gravitationally bound to a stellar object.
binary (minor) planet: is a celestial body that is orbiting another (minor) planet for which the system’s barycenter resides above the surface of both bodies.
These definitions solve some hairy dilemmas. For one, planets orbit around the majority of most stars in the Universe, not just the Sun as Resolution 5A was only intended. Planets can also exist gravitationally not bound to a star – the result of it own molecular cloud collapse without a star or expulsion from a stellar system. One could specify gravitational expulsion however, it is possible that explosive events occur that cause the disintegration of a star and its binding gravity or creates such an impulse that a planet is thrusted out of a stellar system. Having an atmosphere certainly doesn’t work. Astronomers are already anticipating Mars or Earth-sized objects deep in the Oort cloud that could have no atmosphere – frozen out and also despite their size, not be able to “clear their neighborhood.”
An animation (above) of Kepler mission planet candidates compiled by Jeff Thorpe. Kepler and other exoplanet projects are revealing that the properties of planets – orbits, size, temperature, makeup – are all extreme. Does Pluto represent one of those extremes – the smallest of planets? (Credit: NASA/Kepler, Jeff Thorp)
The need to create a lower-end limit to what is a planet reached a near fever pitch with the discovery of a Trans-Nepturnian Object (TNO) in 2005 that is bigger than Pluto – Eris. Dr. Michael Brown of Caltech and his team led in the discovery of bright large KBOs. There was not just Eris but many of nearly the same size as Pluto. So without clause (c), one would be left with a definition for planet that could allow the count of planets in our Solar System to rise into the hundreds maybe even thousands. This would become a rather unmanageable problem; the number of planets rising year after year and never settled and with no means to make reasonable comparisons between planetary systems throughout our galaxy and even the Universe.
The book that tells the story of discovery – trans-Neptunian objects (TNO) that led to the downfall of Pluto from full planethood to that of a dwarf. The 2006 IAU decision was a pre-emptive strike to stave off a proliferation of planets in our system. It worked but “killed” Pluto. Did it have it coming? Dr. Brown also agrees that the present definition of planet is flawed and incomplete. (Photo Credits: Caltech/M.Brown)
Two more celestial body types follow that are proposed to round out the set.
moon: is a celestial body that a) orbits a (minor) planet and b) for which the barycenter of its orbit is below the surface of its parent (minor) planet.
This creates the possibility of a planet-moon system such that its barycenter is above the surface of the larger body. Pluto and Charon are the most prominent case in our Solar System. In such cases, if one body meets the criteria of a (minor)planet, then the other body can also be assessed to determine if it is also a (minor) planet and the pair as binary (minor) planets. If the primary body was a minor planet, it is possible that the barycenter could be above its surface but the secondary body does not meet all the criteria of a minor planet, specifically “differentiated interior”.
The definition of moon is compounded by the existence of, for example, asteroids with moons. For such objects, the smaller object is defined as a satellite.
Satellite: is a celestial body that a) orbits another celestial body, b) whose parent body is not a (minor) planet.
Another permissible term is moonlet which could be used to describe both very small moons such as those found in the Jovian and Saturn systems or a small body orbiting an asteroid or comet. Moonlet could replace satellite.
The discriminator between planet and moon is not mass but simply whether the celestial body orbits a (minor) planet and the barycenter resides inside the larger body. The definition of moon excludes the possibility of a planet orbiting another planet except in the special case of binary (minor) planet.
Defining a lower size limit to “Planet” is necessary to compare stellar systems and classify. A limit based on the body’s average surface pressure and temperature or the surface gravity could define a limit. While they could, they are not practical because of the extremes and diverse combinations of conditions. Strange objects would fall through the cracks.
Removing clause (c) – “has cleared the neighborhood around its orbit” – will avoid a future conflict such as a very low mass star with a plutoid-sized object or smaller, in a close orbit that has cleared its neighborhood.
Additionally, choosing to declare that Pluto becomes the “standard weight” that differentiates minor planet from planet sets a precedent. In an era in which computers measure and tally the state of our existence, setting this limit to include Pluto and return it as the ninth planet of our Solar System, is, in a small but significant way, a re-declaration of our humanity. Soon we will be challenged by artificial intelligence greater than ours; we are already have. Where will we stand our ground?
Forget about Pluto for a moment. Should Eris be our tenth planet? Like Pluto it has a prominent moon- Dysnomia. Human perception and conceptions of the Universe have shaped our view of the Solar System. The Ptolemaic system (Earth centered), Kepler’s Harmonic Spheres, even the fact that ten digits reside on our hands impact our impression of the Solar System (Photo Credits:NASA/ESA and M. Brown / Caltech)
The consequences of this proposed set of definitions, makes Ceres a minor planet and no longer an asteroid. Many trans-Neptunian objects discovered in this century become minor planets. Of the known TNOs only Pluto and Eris meets the criteria of planet.The dwarf planet Eris would become the tenth planet. Makemake, Sedna, Quaoar, Orcus, Haumea would be minor planets. By keeping Pluto a planet and defining it as the standard bearer, only one new planet must be declared. Surely, more will be found, very distant, in odd elliptical and tilted orbits. The count of planets in our solar system could rise by 10, 20 maybe 50 and perhaps this would make the definition untenable but maybe not. So be it. New Horizons will fly by a dwarf planet in July but this should mark the beginning of the end of the present set of definitions.
Three perspectives of a ten planet Solar System. No longer Earth centered, or with harmonic spheres but now with planets outside the ecliptic plane and growing. How many planets would be too many? (Credits: Wikimedia, T.Reyes)
This set of definitions defines a set of celestial bodies that consistently covers the spectrum of known bodies. There is the potential of exotic celestial objects that are spawned from cataclysmic events or from the unique conditions during the early epochs of the Universe or from remnants of old or dying stellar objects. Their discovery will likely trigger new or revised definitions but these definitions are a good working set for the time being. Ultimately, it is the decision of the IAU but the sharing of knowledge and the democratic processes that we cherish permits anyone to question and evaluate such definitions or proclamations.To all that share an interest in Pluto as or as not a planet raise your hand and be heard.
A video from 2014 by Kurz Gesagt describing the Pluto-Charon system. Is this a binary planet system or one of the “dwarf” variety?
My condolences to the friends and family of Tammy Plotner, the first regular contributing writer to Universe Today. Can’t we all relate to what drew Tammy to write about the Universe? She wrote outstanding articles for U.T.
The path of New Horizons through Pluto's growing family. (Image Credit: NASA/ESA/A. Field STScl).
As reported here on Universe Today last week, the SETI Institute has invited the public to vote on the names of Pluto’s 4th and 5th moons. Discovered in 2011 and 2012 respectively, researcher and co-discoverer Mark Showalter will take these names before the International Astronomical Union (IAU) after voting closes on February 25th, 2013.
But days after the polling opened, a curious twist in the tale occurred that Star Trek’s Mr. Spock would only describe as “Fascinating.”
William Shatner, James T. Kirk himself, proposed the name Vulcan for one of Pluto’s unnamed moons. Fans and Trekkies worldwide rallied, and as of writing this, Vulcan enjoys a comfortable lead over Cerberus and Styx which are vying for the 2nd place position.
This astronomical horse-race has the propensity to get interesting. In order to be considered, the IAU’s naming convention simply states “Those that share Pluto’s orbital rhythm take the name of underworld deities,” And the named moons of Charon, Nix & Hydra all follow this convention. Shatner’s case for Vulcan does cite the god as “The nephew of Pluto” in Roman mythology, but anyone who had studied Roman and Greek mythos knows that familial relations can be proven between nearly any given god and/or goddess.
Interestingly, Showalter turned down Shatner’s second Star Trek/mythological suggestion of Romulus, citing that Romulus and Remus are already the names of the moons of asteroid 87 Silvia. While the “double naming” of objects in the solar system isn’t unheard of, it may be a definite strike against a proposal. Cerberus, Orpheus, Hypnos & Persephone are all names in the running that are all also assigned to asteroids.
On February 14th, researchers “Opened up the Gates of Hell” a bit further and took more mythological nominations into the running, adding Elysium, Hecate, Melinoe, Orthrus, Sisyphus, Tantalus, Tartarus and Thantos into the fray. You can write-in candidates such as “Donald,” & “Goofy,” but these stand a proverbial snowball’s chance in Hades of being accepted. Perhaps the backing of a starship captain would help, if Adama or Han Solo were available for hire…
Still, one wonders if the name Vulcan will make it past the gate-keepers at the IAU. The IAU has sparked controversy surrounding Pluto before, in its 2006 decision that angered 5th graders everywhere when they demoted Pluto to dwarf planet status. No solar system body currently holds the name of Vulcan, although one hypothetical one once did; the tiny fleeting world that was once thought to be interior to Mercury’s orbit. Several astronomers even claimed to witness transits of the fleeting world across the face of the Sun, and up until the late 19th century, you could still find Vulcan in many astronomy texts. While the idea of Vulcan as a planet interior to Mercury is out (think of how many telescopes, both amateur and professional, now continuously monitor the Sun daily) it’s not out of the question that a small group of asteroids less than 10 kilometres in size tentatively dubbed “Vulcanoids” may still inhabit the space interior to Mercury.
Fans of Pluto unite… could Vulcan spark a repeat protest? (Wikimedia Commons image in the Public Domain).
But if nothing else, the poll is a fun exercise to watch as astronomy fans worldwide delve into mythological lore and dig out the names of obscure gods and goddesses. A similar debate on mythological merits swirled around the naming of the moon of dwarf planet Orcus, ultimately named Vanth in 2009.
While only two names will be selected for P4 & P5, the other denizens of the underworld may just get their day in July 2015 when NASA’s New Horizons spacecraft gives us the first close up look at Pluto and friends. Previous “first flybys” of other planets and asteroids have turned up new moons before, and Pluto may be no different.
“The discovery of so many small moons indirectly tells us that there must be lots of small particles lurking unseen in the Pluto system,” stated Harold Weaver of the Johns Hopkins University of Applied Physics Laboratory. Such debris will be a definite concern as scientists seek to thread the spacecraft’s trajectory past Pluto and its moons.
A young Clyde Tombaugh with one of his famous homemade telescopes. (Credit : NASA/GSFC).
Discovered 83 years ago to the day on February 18th, 1930 by American astronomer Clyde Tombaugh, Pluto remains an uncharted corner of the solar system. Mr. Tombaugh passed away on January 17th, 1997, and an ounce of his ashes are aboard the New Horizons spacecraft which, along with the Pioneer 10 & 11 and Voyager 1 & 2 spacecraft, are escaping the solar system to wander along the galactic plane.
I’ve also got a proposal out in the running. By naming one of Pluto’s moons Alecto, we would honor Clyde with the inclusion of his initials “CT” on a moon. There is precedent for such a clever tribute before; James Christy honored his wife Charlene in the naming of Pluto’s large moon Charon and Mike Brown paid homage to his wife Diane by naming Eris’s moon Dysnomia.
Whatever happens, it’ll be interesting to see what transpires in the final names of P4/P5 are selected. Hopefully it won’t end in a showdown pitting Trekkies against the IAU… but don’t forget, the Trekkies did keep a television series on the air and got a space shuttle re-named!
The Ten Special Commandments for a Would-Be Planet Hunter, according to Clyde Tombaugh. Scan courtesy of Toney Burkhart.
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Back in 1989, amateur astronomer Toney Burkhart found out that Clyde Tombaugh was going to be giving a talk in San Francisco, just a short distance from Burkhart’s home. Trouble was, he found out only about 10 minutes before the presentation was going to start, so he rushed over and arrived just in time to hear Tombaugh’s talk, where he told amusing stories of how he found Pluto, and what he went through with night after night in a cold observatory taking photographs and comparing the glass plates, looking for a planet in the outer solar system. Then Tombaugh shared read his version of the Ten Commandments, called, “Ten Special Commandments for a Would-Be Planet Hunter.”
Afterward, the posters of the Commandments were being sold as a fund raising event.
“Clyde was going around the country to raise money for scholarships for young people to study planetary science,” Burkhart told Universe Today. “There were a lot of people there in the lobby buying posters autographed by Clyde Tombaugh and I wanted one very much.”
However, when Burkhart went to purchase one, he discovered that in his haste to leave his home, he had forgotten his billfold.
“I waited until everything was over and thought that I would at least go over and say hi to Clyde and tell him how much I thought of his hard work and to shake his hand, at least,” Burkhart said, and Tombaugh was more than happy to chat with an fellow astronomy enthusiast.
“While I was chatting with Clyde, I told him that I wish I brought money to buy one of the posters. He looked at me and smiled and said, ‘Well, that’s alright.’” And I said no, I really would have bought one if I had not ran out of the house and forgot my billfold. He was holding his notes and I asked him, what are you going to do with those notes, throw them away?”
Burkhart said Tombaugh smiled and replied that he couldn’t give away his notes, as he had more talks to give, but said he could mail them to Burkhart after his tour was over.
Burkhart offered to send Tombaugh a check later, or at least pay for postage, but Tombaugh looked at him and said, “No, that’s OK, I see you are really into astronomy and it would be my pleasure to give it you.”
Grateful, Burkhart asked if Tombaugh could autograph it, not for Burkhart but for his son Jason. Tombaugh took Burkhart’s address, and true to his word, about a month later Burkhart received Tombaugh’s personal version of the Commandments, with corrections made in pen, (the corrections were made by Tombaugh’s wife, Patricia, Burkhart said) along with his autograph. “I have them in safekeeping to leave to my son to have and hopefully give them to his kids,” Burkhart said.
Here are the the Ten Special Commandments for a Would-Be Planet Hunter, according to Clyde Tombaugh
1. Behold the heavens and the great vastness thereof, for a planet could be anywhere therein.
2. Thou shalt dedicate thy whole being to the search project with infinite patience and perseverance.
3. Though shalt set no other work before thee for the search shall keep thee busy enough.
4. Though shalt take the plates at opposition time lest thou be deceived by asteroids near their stationary positions.
5. Though shalt duplicate the plate of a pair at the same hour angle lest refraction distortions overtake thee.
6. Thou shalt give adequate overlap of adjacent plate regions lest the planet play hide and seek with thee.
7. Thou must not become ill in the dark of the moon lest thou fall behind the opposition point.
8. Thou shalt have no dates except at full moon when long exposure plates cannot be taken at the telescope.
9. Many false planets shall appear before thee, hundreds of them, and thou shalt check every one with a third plate.
10. Thou shalt not engage in any dissipation, that thy years may be many for thou shalt need them to finish the job!
Clyde W. Tombaugh
14 March 1989
Burkhart shared the scan of Tombaugh’s notes on his Facebook page.
