Tag Archives: Pluto

Frozen pond on Pluto

Cool image time! The New Horizons’ science team on Thursday released a new image, showing a remarkable frozen pond on Pluto. As they note:

“In addition to this possible former lake, we also see evidence of channels that may also have carried liquids in Pluto’s past,” said Alan Stern, Southwest Research Institute, Boulder, Colorado—principal investigator of New Horizons and lead author of a scientific paper on the topic submitted to the journal Icarus.

This feature appears to be a frozen, former lake of liquid nitrogen, located in a mountain range just north of Pluto’s informally named Sputnik Planum. Captured by the New Horizons’ Long Range Reconnaissance Imager (LORRI) as the spacecraft flew past Pluto on July 14, 2015, the image shows details as small as about 430 feet (130 meters). At its widest point the possible lake appears to be about 20 miles (30 kilometers) across.

I have not posted the image here, because I have already posted this image on Behind the Black, back on October 6, 2015, in which I wrote in part,

The image shows what looks like an enclosed lake of some material, probably nitrogen, with the bedrock entrapping it solid ice. In addition, as you move away from the shore and head uphill it looks like you travel across several geological layers made of different materials. Figuring out how they formed in this way could probably keep a geologist busy for his or her entire life.

I had also then noted how I expected the scientists would be “drooling” over this image, and that I expected a full press release on it at some point. It took six months, but here we are.


Pluto 8 months after fly-by

The New Horizons science team today published five papers summarizing what they have so far learned from the data obtained during last year’s July 14 fly-by and since downloaded.

Two of the many discoveries are to me the most interesting: The first illustrates Pluto’s strange and very active geology:

Age-dating of Pluto’s surface through crater counts has revealed that Pluto has been geologically active throughout the past 4 billion years. Further, the surface of Pluto’s informally named Sputnik Planum, a massive ice plain larger than Texas, is devoid of any detectable craters and estimated to be geologically young – no more than 10 million years old.

Moreover, the materials that cause Pluto to be geologically active are much more complicated than anything on Earth:

Scientists studying Pluto’s composition say the diversity of the planet’s landscape stems from eons of interaction between highly volatile and mobile methane, nitrogen and carbon monoxide ices with inert and sturdy water ice. “We see variations in the distribution of Pluto’s volatile ices that point to fascinating cycles of evaporation and condensation,” said Will Grundy, from Lowell Observatory in Flagstaff, Arizona, and lead author of the composition paper. “These cycles are a lot richer than on Earth, where there’s really only one material that condenses and evaporates – water. On Pluto, there are least three materials, and while they interact in ways we don’t yet fully understand, we definitely see their effects all across Pluto’s surface.”

The second discovery that fascinates me has to do with the formation of Pluto and all its moons:

The high albedos (reflectiveness) of Pluto’s small satellites are entirely different from the much lower albedos of the small bodies in the general Kuiper Belt population (which range from about 5 to 20 percent). This difference lends further support to the idea that these satellites were not captured from the general Kuiper Belt population, but instead formed by agglomeration in a disk of material produced in the aftermath of the giant collision that created the entire Pluto satellite system.

In other words, Pluto and its moons are not a collection of different Kuiper Belt objects brought together over time. Instead, they formed together.


Clouds on Pluto?

A report from New Scientist today claims that the New Horizons science team has possibly seen individual clouds in some images.

Grundy had spotted features in the haze on the edge – or “limb” – of Pluto that seemed to stand out from the distinct layers. But more intriguingly, he had also seen a bright feature crossing different parts of the landscape, suggesting it was hovering above. The email kicked off a discussion as to whether the clouds were real, because it was difficult to see whether they cast shadows on the ground. The team also deliberated over the exact distinction between clouds and hazes. “One way to think of it is that clouds are discrete features, hazes widespread,” wrote Alan Stern, who heads up the New Horizons mission.

There has been no public mention of the clouds, suggesting that the team isn’t sure about the detection.


Methane ice on Pluto’s mountain peaks

New images from New Horizons of the dark Cthulhu region have revealed white-capped mountain peaks, thought to be methane ice.

Scientists think this bright material could be predominantly methane that has 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 from Space Telescope Science Institute, Baltimore, Maryland.

We as humans are attracted to features on other worlds that remind us of Earth, mainly because this allows us to quickly understand what we are seeing. It is important however to remind ourselves continually that Pluto is not Earth, and is in fact a very alien place. Many things we think we recognize are really very different than what we assume. For example, the methane ice here is coating mountains made of water ice that is as stable as granite in Pluto’s super cold environment.

One more thing: It appears that at this point, seven months after New Horizons flew past Pluto, they have still only downloaded less than half the data obtained. This is not a problem, as this is how things were planned, but it does mean that there are likely many more discoveries yet for us to see.


A frozen underground ocean on Charon?

Data from New Horizons of the surface of Pluto’s moon Charon now suggests that the satellite once had an underground ocean that is now frozen.

Charon’s outer layer is primarily water ice. When the moon was young this layer was warmed by the decay of radioactive elements, as well as Charon’s own internal heat of formation. Scientists say Charon could have been warm enough to cause the water ice to melt deep down, creating a subsurface ocean. But as Charon cooled over time, this ocean would have frozen and expanded (as happens when water freezes), pushing the surface outward and producing the massive chasms we see today.


The first geology map of Pluto

Geology map of Pluto

The New Horizons science team has now released the first geology map of a portion of Pluto, seen by the spacecraft during its fly-by last year.

It is definitely worth your while to take a look at the full image, along with the legend explaining the different surface features. Most of the geological terms are merely descriptive, but the careful breakdown still provides a much deeper understanding of what is there.


The floating mountains of Pluto

Pluto's floating mountains

The New Horizons science team has released a new image of Pluto’s smooth heart-shaped area, dubbed Sputnik Planum, focusing this time on the mountains of water ice that pop up through the plain and are apparently floating on the nitrogen sea, having broken off from the shoreline.

Because water ice is less dense than nitrogen-dominated ice, scientists believe these water ice hills are floating in a sea of frozen nitrogen and move over time like icebergs in Earth’s Arctic Ocean. The hills are likely fragments of the rugged uplands that have broken away and are being carried by the nitrogen glaciers into Sputnik Planum. ‘Chains’ of the drifting hills are formed along the flow paths of the glaciers. When the hills enter the cellular terrain of central Sputnik Planum, they become subject to the convective motions of the nitrogen ice, and are pushed to the edges of the cells, where the hills cluster in groups reaching up to 12 miles (20 kilometers) across.

I have significantly cropped the image to show it here. Be sure and check out the full version, because there is a wealth of fascinating details in it.


Water ice on Pluto’s surface

The uncertainty of science: An analysis of data from New Horizons suggests that water ice is more widespread on Pluto’s surface than previously believed.

The new map shows exposed water ice to be considerably more widespread across Pluto’s surface than was previously known — an important discovery. But despite its much greater sensitivity, the map still 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 (far north on the encounter hemisphere). This indicates that at least in these regions, Pluto’s icy bedrock is well hidden beneath a thick blanket of other ices such as methane, nitrogen and carbon monoxide.

As the press release notes, water ice is actually “Pluto’s crustal ‘bedrock'”, so there really is plenty there. It is just buried below a surface of methane, nitrogen, and carbon monoxide “topsoil”.


New spectacular images of Pluto

Pluto's mountainous shoreline

Many cool images! The New Horizons science team has today released new images from the spacecraft’s close fly-by of Pluto.

These latest pictures are part of a sequence taken near New Horizons’ closest approach to Pluto, with 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 planet. In these new images, New Horizons captured a wide variety of spectacular, cratered, mountainous and glacial terrains.

I have cropped and lowered the resolution of the image above to fit it here. Make sure you click on the link to see it and the other images. As they note,

In this highest-resolution image from NASA’s New Horizons spacecraft, 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. Several sheer faces appear to show crustal layering, perhaps related to the layers seen in some of Pluto’s crater walls. Other materials appear crushed between the mountains, as if these great blocks of water ice, some standing as much as 1.5 miles high, were jostled back and forth. The mountains end abruptly at the shoreline of the informally named Sputnik Planum, where the soft, nitrogen-rich ices of the plain form a nearly level surface, broken only by the fine trace work of striking, cellular boundaries and the textured surface of the plain’s ices (which is possibly related to sunlight-driven ice sublimation).

Today’s release also includes a short animation of a faint distant Kuiper Belt object, assembled by four images taken by New Horizons. The images don’t show much more than a streak of light, but the feat of imaging this object by a spacecraft billions of miles away in this manner is breath-taking.


Ice volcanoes, spinning moons, and more proof of geologic activity

The New Horizons science team has released more results from the spacecraft’s July 14 fly-by, revealing the existence of what look like two giant ice volcanoes on Pluto, data that suggests the smaller moons spin like tops, and a census of Pluto’s craters that show them distributed very unevenly across the planet’s surface, suggesting that large parts of Pluto’s surface have been resurfaced and thus have been geologically active.

One discovery gleaned from the crater counts also challenges the most popular theory about the formation of objects in the Kuiper Belt.

Crater counts are giving the New Horizons team insight into the structure of the Kuiper Belt itself. The dearth of smaller craters across Pluto and its large moon Charon indicate that the Kuiper Belt likely had fewer smaller objects than some models had predicted. This leads New Horizons scientists to doubt a longstanding model that all Kuiper Belt objects formed by accumulating much smaller objects of less than a mile wide. The absence of small craters on Pluto and Charon support other models theorizing that Kuiper Belt objects tens of miles across may have formed directly, at their current—or close to current—size.

In fact, the evidence that many Kuiper Belt objects could have been “born large” has scientists excited that New Horizons’ next potential target – the 30-mile-wide (40-50 kilometer wide) KBO named 2014 MU69 – which may offer the first detailed look at just such a pristine, ancient building block of the solar system.

As always, the results here are significantly uncertain. They are giving us a glimpse into the geology of rocky planets far from stars, but only a glimpse. I guarantee that any theories formed from this data will be incomplete and will likely be proven wrong.


Pluto’s meandering canyons

canyons of Pluto

Cool image time! In scrolling through the new raw images downloaded from New Horizons today I came across an image, one of several, that showed what clearly appeared to be meandering canyons carved by flowing liquid.

To show it here, I have cropped it and reduced its size somewhat, highlighting the most interesting features. As you can see, the largest canyon not only appears to have a dark floor, it cuts right through an older crater. Smaller canyons do the same thing. In addition, many of the craters seem to be ponded with the same dark material that floors the canyons, while some of the smaller canyons show tributaries that come together, just like rivers. Are these flows of liquid nitrogen?

I eagerly await the conclusions of the scientists, who are probably only slightly less baffled by these features as I am.

Be sure and check out the full image, as well as the other raw images. The data continue to come in from New Horizons, but the science team is no longer under the same kind of public pressure to make announcements or hold press conferences. There are gems hidden there that are worth looking at, even if they are not as yet accompanied by any scientific analysis.


Pluto in 3D

The New Horizons science team has released its first 3D image of the surface of Pluto.

You need red/blue stereo glasses to view it.

The image shows an ancient, heavily cratered region of Pluto, dotted with low hills and cut by deep fractures, which indicate extension of Pluto’s crust. Analysis of these stereo images shows that the steep fracture in the upper left of the image is about 1 mile (1.6 kilometers) deep, and the craters in the lower right part of the image are up to 1.3 miles (2.1 km) deep. Smallest visible details are about 0.4 miles (0.6 kilometers) across.

My impression of the image, using the glasses, makes me wonder if they have exaggerated the vertical depth so that it would stand out. The craters look more like pits than craters. And if they didn’t exaggerate the vertical depth, then that means that impacts on Pluto produce craters that are very different than those seen in the inner solar system.


Another Pluto Moon revealed


The uncertainty of science: The New Horizons science team has released their best image of Pluto’s moon Kerberos, finding it to be nothing like what they expected.

Before the New Horizons encounter with Pluto, researchers had used Hubble Space Telescope images to “weigh” Kerberos by measuring its gravitational influence on its neighboring moons. That influence was surprisingly strong, considering how faint Kerberos was. They theorized that Kerberos was relatively large and massive, appearing faint only because its surface was covered in dark material. But the small, bright-surfaced, Kerberos now revealed by these new images show that that idea was incorrect, for reasons that are not yet understood.

Instead, Kerberos is much smaller than expected, and its surface is bright, suggesting it is covered by relatively clean ice. It is also double lobed, kind of like Comet 67P/C-G.


Ice and blue skies on Pluto

New data downloaded from New Horizons has confirmed the presence of ice on the planet’s surface, as well as suggesting that the planet’s sky might actually be colored blue.

The haze particles themselves are likely gray or red, but the way they scatter blue light has gotten the attention of the New Horizons science team. “That striking blue tint tells us about the size and composition of the haze particles,” said science team researcher Carly Howett, also of SwRI. “A blue sky often results from scattering of sunlight by very small particles. On Earth, those particles are very tiny nitrogen molecules. On Pluto they appear to be larger — but still relatively small — soot-like particles we call tholins.”

Scientists believe the tholin particles form high in the atmosphere, where ultraviolet sunlight breaks apart and ionizes nitrogen and methane molecules and allows them to react with each other to form more and more complex negatively and positively charged ions. When they recombine, they form very complex macromolecules, a process first found to occur in the upper atmosphere of Saturn’s moon Titan. The more complex molecules continue to combine and grow until they become small particles; volatile gases condense and coat their surfaces with ice frost before they have time to fall through the atmosphere to the surface, where they add to Pluto’s red coloring.


Guess where?

Pluto lake

I found the image on the right while trolling about on the various raw image sites for NASA’s planetary missions. No press release yet, and maybe there never will be one. I do know the scientists involved in this particular mission are right now drooling over the details available in the full resolution image, which I have cropped and reduced to fit on the right. Take a look and you will drool as well.

Want to know where this is? I bet you have already guessed, but if you need help, click on the “read more” link below, where I have also added some comments.
» Read more


Charon in color


The New Horizons science team has released new high resolution images of Pluto’s moon Charon, including the global enhanced color view on the right.

High-resolution images of the Pluto-facing hemisphere of Charon, taken by New Horizons as the spacecraft sped through the Pluto system on July 14, and transmitted to Earth on Sept. 21, reveal details of a belt of fractures and canyons just north of the moon’s equator. This great canyon system stretches across the entire face of Charon, more than a thousand miles, and probably around onto Charon’s far side. Four times as long as the Grand Canyon, and twice as deep in places, these faults and canyons indicate a titanic geological upheaval in Charon’s past. “It looks like the entire crust of Charon has been split open,” said John Spencer, deputy lead for GGI at the Southwest Research Institute in Boulder, Colorado. “In respect to its size relative to Charon, this feature is much like the vast Valles Marineris canyon system on Mars.”

The team has also discovered that the plains south of the canyon, informally referred to as Vulcan Planum, have fewer large craters than the regions to the north, indicating that they are noticeably younger. The smoothness of the plains, as well as their grooves and faint ridges, are clear signs of wide-scale resurfacing.

In many ways these images remind me of an upside-down Mars, with the smooth lower plains in the south instead of the north. Obviously, the causes on Charon are going to be significantly different than those on Mars.


New Pluto images

thumbnail of Pluto closeup

Cool image time! The New Horizons team has released some new images. A thumbnail of what I think is the most interesting image is shown on the right. Be sure to look at the full resolution image. It shows a flat plain of what look like frozen polygon plates with a thin layer of what appear to be dunes. In the center some rocks poke out like islands, with what looks like a wind-swept wake to the right. The wake could be caused by Pluto’s very thin atmosphere. Or maybe there are currents that slowly push the frozen plates past the harder rocks (which probably are ice, which in Pluto’s very cold environment has the structural strength of granite).

These images were posted on the New Horizons website with no accompanying press release. I think the science team has decided it will just upload them, and reserve press releases for when they have accumulated enough data to announce some intelligent conclusions. Right now, they can only speculate as wildly as I from these images. It is reasonable to give them the time to assess the data more closely before announcing any explanations. At the same time, we should also congratulate them for posting the images immediately so that others can see them.

Update: a press release was released, though it really doesn’t add much except review the images.


New images from Pluto

Mountains and glaciers on Pluto

Cool image time! As expected, the New Horizons team has made its weekly press announcement, though on Thursday instead of Friday, releasing new images taken by the spacecraft during its July 14 flyby.

The image above has been cropped and reduced by me to fit. Make sure you look at the full resolution image.

Just 15 minutes after its closest approach to Pluto on July 14, 2015, NASA’s New Horizons spacecraft looked back toward the sun and captured a near-sunset view of the rugged, icy mountains and flat ice plains extending to Pluto’s horizon. 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. The image was taken from a distance of 11,000 miles (18,000 kilometers) to Pluto; the scene is 230 miles (380 kilometers) across.

The mountains are made of ice, the glacier flows of nitrogen.

The main takeaway so far is that Pluto might have a “hydrological” cycle like Earth’s, but instead of water cycling from ice to water to gas to rain, it appears it is nitrogen and other strange materials.


Rivers and lakes on Pluto?

Cool image time! Though the New Horizons science team will likely not issue their next press release until Friday, they appear to be posting new images on their website on a daily basis. From those images I pulled out the one below, which to fit I have cropped and reduced slightly in size. Be sure to go to the full image.

Do you see what I see? It appears that there are meandering braided dry streambeds on Pluto, draining into what appears to be a large basin.

Rivers and lakes on Pluto?

Assuming my guess of what this is is correct, this is obviously not a streambed created by water. Earlier images showed nitrogen ice flows and glacier-like geology. It is possible this new image is observing evidence of past nitrogen riverbeds and nitrogen lakes.

Expect a very interesting press release from New Horizons later this week.


The first sharp pictures of Pluto’s moon Nix

Link here.

I am on the road so it is presently difficult to post images. Go to the link. Emily Lakdawalla does a fine job taking the New Horizon images and enhancing them to bring out the detals. And trust me, the details are really strange and cool. Nix looks like a chunk of a planet that got ripped apart.


New Pluto images!

Chaos region

Cool image time! The first of what will likely be weekly image releases for the next few months from New Horizons was made public today, and shows Pluto’s surface to be incredibly complex and confusing.

New close-up images of Pluto from NASA’s New Horizons spacecraft reveal a bewildering variety of surface features that have scientists reeling because of their range and complexity. “Pluto is showing us a diversity of landforms and complexity of processes that rival anything we’ve seen in the solar system,” said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute (SwRI), Boulder, Colorado. “If an artist had painted this Pluto before our flyby, I probably would have called it over the top — but that’s what is actually there.”

The image above only shows one cropped section. Make sure you look at the full image. In the section I’ve cropped we can see nitrogen ice flowing around chunks of some darker harder material, probably water ice. On the left, near the small crater, is what appears to be a canyon formed by flowing liquid. Other images show what appear to be dunes!

It appears, as is typical of scientific exploration, that we are going to be left with more questions from the New Horizons’ data than we had before the fly-by occurred.


Data from New Horizons does not match what is seen from Earth

The uncertainty of science: Planetary geologists are presently baffled by a conflict in the atmospheric data between New Horizons and data gathered from Earth.

On 29 June, a few weeks before the fly-by, Young organized astronomers across New Zealand and Australia to watch Pluto as it passed in front of a distant star. Tracking how the star’s light faded during the passage provided information on how much gas is in Pluto’s atmosphere. Using the same method, planetary scientists have seen the atmosphere grow denser since 1988 — and analysis of the 29 June observations shows that the trend remains intact. Young calculates that the current atmospheric pressure at Pluto’s surface is 22 microbars (0.022 pascals), or 22-millionths the pressure at sea level on Earth.

But on 14 July, New Horizons measured Pluto’s surface pressure as much lower than that ­— just 5 microbars. “How we link the two, we’re still working on,” says Cathy Olkin, a deputy project scientist for New Horizons at SwRI.

The difference could simply be that Pluto’s atmosphere is not smooth, that some regions are dense while others are thin, and New Horizons happened to look at a thin place. The Earth observations don’t have the resolution to separate the two.

There are other proposals to explain the problem. Regardless, the answer is likely hidden in the data from New Horizons that has still not been downloaded back to Earth. In a few months, all might very well become clear.

Or not, as is the natural state of science.


New Horizons team picks its next Kuiper Belt target

The New Horizons science team has picked its next Kuiper Belt fly-by target beyond Pluto.

New Horizons will perform a series of four maneuvers in late October and early November to set its course toward 2014 MU69 – nicknamed “PT1” (for “Potential Target 1”) – which it expects to reach on January 1, 2019. Any delays from those dates would cost precious fuel and add mission risk. “2014 MU69 is a great choice because it is just the kind of ancient KBO, formed where it orbits now, that the Decadal Survey desired us to fly by,” said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute (SwRI) in Boulder, Colorado. “Moreover, this KBO costs less fuel to reach [than other candidate targets], leaving more fuel for the flyby, for ancillary science, and greater fuel reserves to protect against the unforeseen.”

The press release includes some silly gobbly-gook about how the science team can’t announce this as its official target because they still have to write up a proposal to submit to NASA, which then must ponder their decision and decree it valid. We all know this is ridiculous. Will NASA sit and ponder and make them miss their target? I doubt it.

The fly-by itself will be really exciting, because this object will truly be the most unusual we will have ever gotten a close look at, as it has spent its entire existence far out in the dim reaches of the solar system.


IAU balks at some Pluto names picked by New Horizons team

Irritated that the New Horizons team did not consult with the International Astronomical Union (IAU) before it announced its proposed names for many Pluto features, IAU officials are now threatening to reject them once submitted.

“Frankly, we would have preferred that the New Horizons team had approached us before putting all these informal names everywhere,” said Rosaly Lopes, a senior research scientist at NASA’s Jet Propulsion Laboratory who is a member of the IAU’s Working Group for Planetary System Nomenclature.

The group’s chair, Rita Schulz of the European Space Agency, said the New Horizons team has not yet submitted a formal proposal for naming features on Pluto and its moons. “Usually, there are always some features for which this process goes rather fast, some for which more checks and balances are required (which then takes a bit longer) and there are usually also some names or descriptors that cannot be approved and need to be replaced by others,” she told GeekWire in an email.

There has been a conflict between the IAU and the principal investigator for New Horizons, Alan Stern, for years now. Stern also runs the private company Uwingu, which offers citizens the ability to name unnamed craters on Mars for a fee, without asking the IAU. Stern, like myself, believes that the IAU’s claim that it is the only authority that can approve names for every object not on Earth is hogwash. Stern also strongly objects to the IAU’s decision to demote Pluto’s planetary status to a dwarf planet.

These comments by IAU officials suggest that they are being somewhat petty and are threatening to reject the New Horizons names to get back at Stern.


Where is Pluto’s nitrogen coming from?

As New Horizons’ engineers download data and plan future maneuvers to fly past one of two candidate Kuiper Belt objects, the science team today outlined the background mystery of Pluto’s nitrogen.

Pluto’s atmosphere is similar to Earth’s in that it is predominantly composed of nitrogen (N). But Pluto’s atmosphere is ~98% N, while Earth’s is only ~78% N. Pluto’s atmosphere is also considerably thinner than Earth’s with ~10,000 times lower pressure at the surface.

The nitrogen in Pluto’s atmosphere (in the form of N2 gas) is actually flowing away and escaping the planet at an estimated rate of hundreds of tons per hour. We also see what looks like flowing ice on Pluto’s surface in high resolution images made by New Horizons. The water ice (H2O) that we are familiar with on Earth would be completely rigid and stiff at Pluto’s surface temperatures, but ice made out of N2 would be able to flow like a glacier. So where does all of this nitrogen come from?

They have rejected comets as a source, and have predicted that geologic activity on Pluto itself could dredge the nitrogen up from the planet’s interior. (This prediction by the way was made before the New Horizons’ flyby, which has proved it likely.)

If their theory ends up the answer, then they will also prove that Pluto is losing mass, albeit slowly. Nitrogen from within is being processed out of the interior, into the atmosphere as gas, and then into space because Pluto’s gravity is too small to hold it.


Alan Stern gives the IAU a piece of his mind

New Horizons’ principle investigator yesterday told the International Astronomical Union what he thinks of their definition of a planet:

“It’s bulls—,” he told Tech Insider (and said we could quote him on that).

The problem, Stern said, is that the reclassification largely stemmed from the opinions of astronomers, not planetary scientists. His beef here is that astronomers study a large variety of celestial objects and cosmic phenomena, while planetary scientists focus solely on planets, moons, and planetary systems.

“Why would you listen to an astronomer about a planet?” Stern said. He compared it to going to a podiatrist for brain surgery instead of a brain surgeon. “Even though they’re both doctors, they have different expertise,” Stern said. “You really should listen to planetary scientists that know something about this subject. When we look at an object like Pluto, we don’t know what else to call it.”

Stern’s opinion is not unique among planetary scientists. I have interviewed many, and read reports by others, which consistently say that they object strongly to the IAU’s definition. To them, if a object has enough mass to force it into a sphercial shape, it is a planet.


New Pluto data released


Cool image time! During today’s New Horizons’ press conference, principal investigator Alan Stern noted that only 4%-5% of the data has been recovered. They have finished first phase of download and are moving into second phase, which will be dominated by engineering and other data, not images. So, for the next couple of months they will only be able to release images once and awhile. Beginning in September images, however, they will begin downloading images at a much faster pace.

Some results from today:
» Read more


Worlds without end

Last week’s fly-by of Pluto by New Horizons illustrated forcefully once again the power of exploration on the human mind, and how that exploration always carries surprises that delight and invigorate us.

First of all, the images from that fly-by demonstrated clearly that the decision by the International Astronomical Union (IAU) to declare Pluto a non-planet was very much premature. Even project scientist Alan Stern himself enthusiastically noted at the start of Friday press conference that Pluto-Charon was a “double planet system”.

The IAU definition itself was faulty and difficult to apply. The clause that required a planet to have “cleared the neighborhood around its orbit” made little sense in the real universe, as even the Earth has not successfully cleared its orbit after several billion years. Was the IAU suggesting the Earth was not a planet?

New Horizons’s discovery last week that even a small object like Pluto, orbiting the Sun on its own with no gas giant nearby to provide tidal heating, can still exhibit significant and on-going geological activity, shows that our understanding of what defines a planet is at this time quite limited. We simply don’t know enough about planetary evolution and formation to definitively define the term. Nor do we have enough knowledge to determine if Pluto falls into that category, though the data strongly suggests that it does.

Are planets made up of only gas giants, rocky terrestrial planets like the Earth, and dwarf planets like Ceres and Pluto? Or are there numerous other as yet unknown categories?
» Read more

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