Pluto Archives

March 2, 2009December 24, 2015 by Anne Minard

Pluto’s Atmosphere Boasts Methane, Warmer Temps

Artist’s impression of how the surface of Pluto might look, if patches of pure methane rest on the surface. At the distance of Pluto, the Sun appears about 1,000 times fainter than on Earth. Credit: ESO

Pluto is certainly frigid, but new research has revealed its atmosphere is a bit warmer.

Astronomers using the European Southern Observatory’s Very Large Telescope have found unexpectedly large amounts of methane in Pluto’s atmosphere, which evidently helps it stay about 40 degrees warmer than the dwarf planet’s surface. The atmosphere warms to -180 degrees Celsius (-356 degrees Fahrenheit), compared to a surface that’s usually -220 degrees Celsius (-428 degrees Fahrenheit).

“With lots of methane in the atmosphere, it becomes clear why Pluto’s atmosphere is so warm,” said Emmanuel Lellouch of the Observatoire de Paris in France. Lellouch is lead author of the paper reporting the results, which is in press at the journal Astronomy and Astrophysics.

Pluto, which is about a fifth the size of Earth, is composed primarily of rock and ice and orbits about 40 times further from the Sun than the Earth.

It has been known since the 1980s that Pluto also has a thin, tenuous atmosphere. Abundant nitrogen, along with traces of methane and probably carbon monoxide, are held to the surface by an atmospheric pressure only about one hundred thousandth of that on Earth, or about 0.015 millibars. As Pluto moves away from the Sun, during its 248 year-long orbit, its atmosphere gradually freezes and falls to the ground. In periods when it is closer to the Sun — as it is now — the temperature of Pluto’s solid surface increases, causing the ice to sublimate into gas.

Until recently, only the upper parts of the atmosphere of Pluto could be studied. By observing stellar occultations, a phenomenon that occurs when a Solar System body blocks the light from a background star, astronomers were able to demonstrate that Pluto’s upper atmosphere was some 50 degrees warmer than the surface. Those observations couldn’t shed any light on the atmospheric temperature and pressure near Pluto’s surface. But unique, new observations made with the CRyogenic InfraRed Echelle Spectrograph (CRIRES), attached to ESO’s Very Large Telescope, have now revealed that the atmosphere as a whole, not just the upper atmosphere, has a mean temperature much less frigid than the surface.

Usually, air near the surface of the Earth is warmer than the air above it, largely because the atmosphere is heated from below as solar radiation warms the Earth’s surface, which, in turn, warms the layer of the atmosphere directly above it. Under certain conditions, this situation is inverted so that the air is colder near the surface of the Earth. Meteorologists call this an inversion layer, and it can cause smog build-up.

Most, if not all, of Pluto’s atmosphere is thus undergoing a temperature inversion: the temperature is higher, the higher in the atmosphere you look. The change is about 3 to 15 degrees per kilometer (.62 miles). On Earth, under normal circumstances, the temperature decreases through the atmosphere by about 6 degrees per kilometer.

The reason why Pluto’s surface is so cold is linked to the existence of Pluto’s atmosphere, and is due to the sublimation of the surface ice; much like sweat cools the body as it evaporates from the surface of the skin, this sublimation has a cooling effect on the surface of Pluto.

The CRIRES observations also indicate that methane is the second most common gas in Pluto’s atmosphere, representing half a percent of the molecules. “We were able to show that these quantities of methane play a crucial role in the heating processes in the atmosphere and can explain the elevated atmospheric temperature,” said Lellouch.

Two different models can explain the properties of Pluto’s atmosphere. In the first, the astronomers assume that Pluto’s surface is covered with a thin layer of methane, which will inhibit the sublimation of the nitrogen frost. The second scenario invokes the existence of pure methane patches on the surface.

“Discriminating between the two will require further study of Pluto as it moves away from the Sun,” says Lellouch. “And of course, NASA’s New Horizons space probe will also provide us with more clues when it reaches the dwarf planet in 2015.”

LEAD IMAGE CAPTION: Artist’s impression of how the surface of Pluto might look, if patches of pure methane rest on the surface. At the distance of Pluto, the Sun appears about 1,000 times fainter than on Earth. Credit: ESO

Source: ESO

January 17, 2009December 24, 2015 by Ian O'Neill

Naming Pluto (Review)

Naming Pluto promotional poster (© Father Films)

[/caption]Naming Pluto explores the chain of events that lead to Pluto’s naming and in 2007 sees Venetia Phair viewing Pluto for the very first time through a telescope, on her 89th birthday, 77 years after Pluto’s discovery. A wonderful, intimate look into the story behind how Pluto got its name. A review of the short film directed and produced by Ginita Jimenez, distributed by Father Films.

In recent years, Pluto has seen its status change from being a planet to what many people view as a planetary underclass. The reasons behind this have been set out by the International Astronomical Union (IAU) to cater for the increasing number of Solar System bodies being discovered; the traditional nine planets have had to make room for a growing minor planet population. Unfortunately, Pluto was at the front line as it inhabits a region of space dominated by the gas giant Neptune, plus thousands of other Kuiper belt objects. Although the mysterious body lost its planetary status (as it does not have the ability to “clear its own orbit”), it has taken the title of “dwarf planet” and now has an entire class of object named in its honour: “Plutoids”.

However, the recent tumultuous history of the traditional “9th planet” has not impacted the fascination we have for Pluto. It has, and always will be, viewed with intrigue and wonder.

The key to Pluto’s romantic tale begins in the year 1930 when a mysterious heavenly was discovered by Clyde Tombaugh, a 23 year-old astronomer working at the Lowell Observatory in Flagstaff, Arizona. However, the honour of naming Pluto didn’t rest on Tombaugh’s shoulders. Over 5000 miles away in Oxford (UK) an 11 year old girl was having breakfast with her grandfather, wondering what this newly discovered planet should be called…

The Pluto system seen from the surface of Hydra (NASA)

Naming Pluto starts out with some stunning visuals from 2006 of NASA’s New Horizons Pluto mission launching from Cape Canaveral. Throughout the opening tour of the Solar System, we can hear the voice of Venetia Burney as she is interviewed by NASA Public Affairs officer Edward Goldstein during the launch.

When Goldstein asks whether she had ever seen Pluto through a telescope, the clear and articulate voice of Venetia replies, “I don’t think I have. I’ve just seen a photograph.” And so the journey begins, where Venetia explains her fascination with Pluto and a number of experts (including the enigmatic Sir Patrick Moore) help to explain the facts behind the discovery of Pluto to the scientific endeavour of the search for “Planet X”.

One of the key moments is when Venetia is describing when she decided on the name for the heavenly body. At age 11, had an acute interest in ancient mythology, so she chose the name because Pluto is the Roman god of the underworld; a fitting name considering the cold, dark nature of Pluto’s 248 year orbit. In a fortuitous chain of events, her grandfather, a former librarian of Oxford University’s Bodleian Library, passed the suggestion via letter to Professor Herbert Hall Turner saying that his granddaughter had chosen a “thoroughly suitable name: PLUTO.” Hall Turner, thrilled with the candidate name, sent Venetia’s idea to colleagues in the USA, at the Lowell Observatory.

Venetia talks about her relationship with Pluto. A model of NASA's New Horizons probe is also in view (© Father Films)

Pouring a cup of tea, Venetia recounts that historic day in 1930. “It was about 8 o’clock and I was having breakfast with my mother and my grandfather,” she says very matter of factually. “My grandfather, as usual, opened the paper, The Times, and in it he read that a new planet had been discovered. He wondered what it should be called. We all wondered. And then I said, “why not call it Pluto?” And the whole thing stemmed from that.”

A special delight is when Venetia visits St. Anne’s Primary School in Surrey to participate in their class project all about Pluto. It goes to show that even young school children have fallen under Pluto’s spell. One 9 year-old pupil, Katie, shares her concerns about Pluto’s demotion, “Some people say that Pluto isn’t a real planet, so I’m looking forward to Venetia coming because I want to find out if that’s true.”

Sir Patrick Moore shares his views on Pluto (© Father Films)

Legendary astronomer Sir Patrick Moore enthusiastically gives his views on Pluto too, having co-authored a 1980 book with discoverer Tombaugh called Out of the Darkness: The Planet Pluto, he is the ideal character to defend the demotion from planet to dwarf planet by the IAU saying, “It’s not demoted! […] you can call it whatever you like. It’s there!” I have been a huge fan of Sir Patrick’s writing, and his regular BBC program The Sky at Night is essential astronomy watching, and has been for the last 50 years!

Other guests on the film uncover the various attributes of Pluto’s discovery, delving into the history and future of the planetary lightweight on the outermost reaches of the Solar System.

Venetia meets Patrick at his home for the second time (© Father Films)

The Naming Pluto adventure culminates in 2006 when Venetia and Sir Patrick meet (for the second time) at his West Sussex home to make an attempt at observing Pluto through the telescope in his garden. Patrick was overjoyed to see Venetia again and chuckles as he introduces her to the camera crew, “The lady who named Pluto!”

“Yes, indeed,” the ever gracious Venetia replies, smiling.

Unfortunately, the UK summer weather conspired against the possibility of clear skies, and any chance of Patrick’s 15″ reflector of spying Pluto was lost. However, there is a fantastic twist in the tale, bringing the whole film to a wonderfully emotional ending.

All in all, Naming Pluto is a fabulous tribute, not only to Venetia, but to the astronomical process. Although Pluto has undergone a change in status these last few years, it remains an important, permanent feature of the Solar System. This well-crafted story gives the viewer an excellent overview of Pluto’s discovery, naming and the magic it holds today for the 9 year-olds at St. Anne’s to Venetia who named the planet nearly 80 years ago…

For more information about Pluto, check out the Guide to Space: Pluto »

A big thank you goes to writer, director and producer Ginita Jimenez for sharing this magnificent production with me. My copy will have pride of place with my growing collection of space science DVDs, a timeless memento of a historic time for astronomy.

If you want your own copy, or want to buy it as a gift, contact Ginita at: [email protected]

Naming Pluto is currently on the international film festival circuit so if you’d prefer watching it on the big screen, and are in the area, please see below. There will also be a blog and updates on www.fatherfilms.com.

THROUGH WOMEN’S EYES – USA
WWW.THROUGHWOMENSEYES.COM
30TH & 31ST JANUARY 2009

JAIPUR INTERNATIONAL FILM FESTIVAL – INDIA
WWW.JIFFINDIA.ORG
FEB/MARCH 2009

SEBASTOPOL DOCUMENTARY FILM FESTIVAL – USA
WWW.SEBASTOPOLFILMFESTIVAL.ORG
MARCH 6-8, 2009

CINEQUEST FILM FESTIVAL – USA
WWW.CINEQUEST.ORG
FEB 25-MAR 08 2009
OFFICIAL SELECTION FOR BEST SHORT FILM AWARD

Details of the film:

Title: Naming Pluto
DVD: 16:9 (FHA) (Colour)
Audio: Stereo & 5.1 Dolby
Duration: 13mins
Language: English
Website: fatherfilms.com

November 10, 2008December 24, 2015 by Ian O'Neill

Plutoid Eris is Changing… But We Don’t Know Why

The mysterious Eris and moons. Credit: NASA

[/caption]Eris, the largest dwarf planet beyond Neptune, is currently at its furthest point in its orbit from the Sun (an aphelion of nearly 100 AU). At this distance Eris doesn’t receive very much sunlight and any heating of the Plutoid will be at a minimum. However, two recent observations of Eris have shown a rapid change in the surface composition of the body. Spectroscopic analysis suggests the concentration of frozen nitrogen has dramatically altered during the two years Eris had been at this furthest point from the Sun. This is very unexpected, there should be very little change in nitrogen concentration at this point in its 557 year orbit.

So what is going on with this strange Plutoid? Is there a mystery mechanism affecting the surface conditions of this frozen moon? Could there be some cryovolcanic process erupting? Or is the explanation a little more mundane?

“We’re really scratching our heads,” says Stephen Tegler of Northern Arizona University in Flagstaff, author of the new Eris research (to be published in the journal Icarus). Tegler and his team analysed spectroscopic data from the 6.5 metre MMT observatory in Arizona and compared their 2007 results with a similar observation campaign by the 4.2 metre William Herschel Telescope in Spain two years earlier in 2005.

During that two year period, the scientists wouldn’t have thought there would be much difference in the two datasets. After all, the reflected sunlight off the surface of Eris should reveal a similar surface composition, right? Actually, the results couldn’t be more surprising. It would appear that within two years, having not changed its distance from the Sun significantly, the surface composition has changed a lot. Normally, this would be expected if a planetary body approaches or travels away from the Sun; the increase or decrease in solar energy would change the weather conditions on the surface. But this situation does not apply to Eris, there is little chance that the Sun could influence the weather on the surface of Eris to any degree (or, indeed, if Eris even has “weather”).

//neo.jpl.nasa.gov/orbits/2003ub313.html'>NASA's Near Earth Program</a>

So what have the researchers deduced from the comparison of the 2005/2007 data? It would appear the spectroscopic methane lines have become diluted by an increased quantity of nitrogen. This means that the 2005 results showed a higher concentration of nitrogen near the surface, whereas the 2007 results show a higher concentration below the surface. For a dwarf planet to demonstrate a very fast change in surface composition appears to show some very dynamic process is at work.

So what could have caused this change? In the case of a dynamic weather process, “it’s very hard to imagine that something that dramatic would be happening on a relatively short time scale,” says Mike Brown of Caltech, a scientist not involved with the research. Another possibility is that 2003ub313 is a cryovolcanic body. Cryovolcanoes can erupt on icy moons or bodies in the Kuiper belt, but rather than spewing molten rock (magma), they erupt volatiles like ammonia, water or (in this case) nitrogen and methane. The ejected cryomagma then condenses into a solid, thus changing the surface composition of the icy body.

But it is not known whether Eris is warm enough for such a process to work. More information on trans-Neptunian object (TNO) cryovolcanism will be examined when NASA’s New Horizons mission reaches Eris’ smaller cousin Pluto in 2015. “If a shrimpy little body like Pluto can do it, Eris can too,” said co-author William Grundy of Lowell Observatory in Flagstaff, Arizona.

However, there is a possibility that the surface composition of Eris hasn’t changed at all. The 2005 and 2007 observations may have been analysing two different regions on the dwarf planet, thus the difference in surface composition (after all, the Plutoid has a rotation period of 26 hours, they would have almost definitely have seen different parts of Eris). So the next step for the researchers is to carry out an extended campaign throughout an “Eris day” to see if the surface composition is in fact patchy, which would be an interesting discovery in itself.

Publication: arXiv:0811.0825v1 [astro-ph]
Original source: New Scientist

October 30, 2008December 24, 2015 by Nancy Atkinson

Charon Imaged by Amateur Astronomers

Pluto and Charon. Credit: Antonello Medugno and Daniele Gasparri

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This past summer, a group of seven amateur astronomers from Italy worked on an observation campaign of Pluto, with hopes of capturing an image of its moon, Charon. “Imaging Charon is very difficult and nobody has spotted it with amateur equipment, so far,” said Daniele Gasparri, one of the members of the group. The team made several attempts, and finally, one member of the group, Antonello Medugno, took this interesting image. “After many calculations,” said Gasparri, “we are sure that this image shows clearly Pluto and Charon, for the first time with amateur equipment.” Comparing the image to the graphic which shows the position of Pluto and Charon on the same date, it’s obvious, they nailed it! This is quite a feat considering their equipment was an “amateur” 14-inch telescope! Also, as The Bad Astronomers points out, Charon wasn’t discovered until 1978, and then a 61-inch telescope was used!

Compare their image to one taken by Hubble:

Hubble image of Pluto and Charon. Credit: NASA

Not bad!!

Gasparri is an astronomy student, and a contributor to the Italian astronomy magazine Coelum. With the support of the magazine, he coordinated the effort to image Charon. Medugno used an 14″ Schmidt-Cassegrain telescope, a Starlight Xpress SXV-H9 CCD camera and a R-IR passband filter.

The image was processed using the Lucy-Richardson Algorithm of the RAW image, composed of 21 frames of 6 seconds of exposure each, with a focal of 8900mm. “All data confirm the image: the magnitude, separation, and position angle,” said Gasparri. Nice work! Check out Gasparri’s website of more astronomical images he has taken.

September 12, 2008December 24, 2015 by Nancy Atkinson

Pluto Spacecraft Gets Brain Transplant

Artist rendition of New Horizons in the Kuiper Belt. Credit: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)

[/caption]

Still seven years away from its rendezvous with Pluto, the New Horizons spacecraft was awoken from hibernation for the second annual checkout of all systems. The spacecraft and its team back on Earth will also undergo three months of operations as the New Horizons will make observations of Uranus, Neptune, and Pluto. But the first order of business was uploading an upgraded version of the software that runs the spacecraftâ€™s Command and Data Handling system. â€œOur â€˜brain transplantâ€™ was a success,â€ says New Horizons Principal Investigator Alan Stern. â€œThe new software â€“ which guides how New Horizons carries out commands and collects and stores data â€“ is now on the spacecraftâ€™s main computer and operating, over a billion miles from home!â€

The mission ops team at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, radioed the software load and the commands to start it earlier this week through NASAâ€™s Deep Space Network of antennas to the spacecraft, now just more than 1.01 billion miles (1.62 billion kilometers) from Earth. In the next 10 days the team will beam up additional new software for both the spacecraftâ€™s Autonomy and Guidance and Control systems.

Space Science Mission Operations Center at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.

Alice Bowman, New Horizons mission operations manager at APL, says the spacecraft and its computers are healthy. â€œThe new software fixes a few bugs and enhances the way these systems operate, based on what weâ€™ve learned in running the spacecraft in the nearly three years since launch,â€ she says. â€œThey also configure the onboard systems to be ready to support the Pluto-Charon encounter rehearsals scheduled for next summer.â€

New Horizons is more than 200 million miles beyond Saturnâ€™s orbit and more than 11 astronomical units (1.02 billion miles) from the Sun, flying about a million miles per day toward Pluto. Annual Checkout 2 (ACO-2) continues through mid-December; follow its progress through frequent updates on the New Horizons Twitter page.

Source: New Horizons Press Release

August 14, 2008December 24, 2015 by Nancy Atkinson

Tyson and Sykes Duke Out the Great Planet Debate; Flatow Almost Flattened

A debate today between astronomer Neil deGrasse Tyson and planetary scientist Mark Sykes, moderated by NPR’s Ira Flatow, addressed the issue of Pluto’s planetary status. There was lots of arm-waving and finger-pointing, endless interruptions, disagreements on details big and small, and battling one-liners. The two scientists sat at a table with the moderator between them and Flatow was often obscured by Tyson and Sykes getting in each other’s faces in eye-to-eye confrontation. At one point, Flatow was hit by Tyson’s ebullient arm motions. Yes, it was heated. But it was fun, too. It ended up being not so much a debate between the Pluto-huggers and the Pluto-haters as a disagreement over the lexicon of astronomy and planetary science and, primarily, the definition of a planet. Pluto’s planetary status was definitely not decided here, and the debate concluded with an amicable agree-to-disagree concurrence that the scientific process is an ongoing, evolving practice. But it wasn’t without fireworks.

At the start of the Great Planet Debate, Flatow laid down the ground rules, which included no throwing of perishable items, but that was about the only rule that didn’t get disregarded. Tyson, director of the Hayden Planetarium in New York and host of Nova ScienceNow, and who is in the camp that Pluto is not a planet, began his opening statements with “It’s simple. The word ‘planet’ has lost all scientific value.” He went on, saying “planet” doesn’t tell you much and you have to ask all sorts of questions such as is it big or small, rocky or gaseous, in the habitable zone or not, etc. “If you have to ask twenty questions after I say I’ve discovered a planet, the word has lost its utility.” Tyson said “planet” had utility far back in time when there wasn’t much else we knew about, but we know so much more now. “If we’re going rely on one word and put them all in one pot, what are we doing as scientists and educators? The time has come to discard the useless words and invent a whole new system to respect the level of science we have achievedâ€¦We’re in desperate need of a new lexicon to accommodate this knowledge,” he said.

Sykes, director of the Planetary Science Institute, and who believes Pluto should be reinstated as a planet, began, “How we categorize things is part of the science process. It is natural for humans to group things together with common characteristics as a tool to better understand and how they work. This applies to biology and astronomy as well.” He continued that we have discovered planets around other stars and continue to find Kuiper Belt objects that will need to be classified, so classifying objects is not a useless task. The IAU (International Astronomical Union) bit the bullet and decided on a classification, but unfortunately, Sykes said, what they came up with was not very useful.

That was the end of decorum, as Tyson interrupted with, “You wanted a definition. They gave you a definition and now you’re complaining about it!”

“Absolutely,” said Sykes, wanting to continue, but Tyson quickly chimed in, “And let me addâ€¦”, where Sykes butted in with “You have to let me start before you add!”

Flatow looked around and said, “I think I’m in a danger zone here.”

Thus began the debate.

Sykes said that any definition has to have a reason, or a purpose. According to the IAU’s definition, planets have to orbit the sun, they have to be round, and they have to have cleared their orbits, among other things. There was immediate confusion with this definition, which Sykes said was a little “goofy.” In order to be a planet, an object has be bigger the farther away it is from the sun, and it ignores the physical characteristics. He believes it’s useful to group things together that are similar and then have subcategories. So, you have planets, under which are terrestrial, gas giants, ice planets, etc.

Tyson said that even for him, the IAU’s definition falls short of taking the total amount of information to task. “If you only want to call round things planets, that puts Pluto in the same class as Jupiter. I happen to like round things. But what other lexicon might be available to group similar things together?”

“That’s why god made subcategories,” said Sykes. “It’s good to have a good general starting point for classifying things.”

Tyson humorously pointed out this debate is big only in the US, which he attributed to Disney’s creation of the lovable, dimwitted cartoon bloodhound named Pluto. School kids, grownups, op-ed writers all say Pluto is their favorite planet. “I am certain that the word ‘plutocracy’ is traceable to what Disney has done, so it’s hard to extricate the sentiment we have for the planet from the dog.”

Sykes said the IAU didn’t expand our perspective on planets, but narrow it. “The planet count went down, and what was the justification of that? The proponents have never given a good explanation of what was motivating that perspective.”

Tyson said numbers aren’t important, but words and definitions are, and we definitely need new ones.

Both scientists gave good arguments for their cause, and since I’m decidedly on the fence with this issue, I found myself leaning towards one option or the other, as each one spoke. Sykes, who wants to see Pluto reinstated as a planet, wants to take what we have and make it better, while Tyson, who thinks Pluto is a comet, wants to start over with new and better words and definitions.

It was an entertaining and educational debate with two well-spoken and intelligent scientists who sometimes weren’t very polite, however. (Sykes said, “When were’ not fighting we get along fine.”) The most important thing, they both agreed though, was that scientists are actually talking about this issue in the public eye and people are interested. But more importantly, the public is seeing the scientific process in action. They said this debate shouldn’t be about making things easy, or worrying about “not confusing the public.” Learning science shouldn’t be rote memorization of lists of objects, but a discussion of how objects are similar and different. “My recommendation to school teachers,” said Tyson “is to get the notion of counting things out of your system and comb the solar system for the richness of objects. Ask about different ways to combine the different objects in our solar system and have a discussion about their different properties.”

The debate will be available online, and we’ll post a link to it here when it is.

Sykes ended with his closing argument: “We both have issues with what happened with the IAU, its part of an ongoing presentation, but the important things is that the public gets to see the debate, and it’s not a battle over what list and what numbers you have, but the debate of the issues. That’s more important whether either of us have convinced you of one perspective. Science in this country is too much memorizing lists promulgated by those in authority. This is helping to expose the messy side of science. This debate is good and positive.”

Tyson ended by saying how charmed he is at the level of public interest in this subject. “How many sciences get to have their issues debated in the op-ed pages and comics?” He said he was happy with the word “planet” until all the data started pouring in from our explorations. “There should be a way to celebrate a new way to think about things. There ought to be a way to capture that” he said.

Obviously, this is not the last word on the subject from either scientist, or either side of the debate.

But that’s a good thing.

For more info on the Great Planet Debate.

August 10, 2008December 24, 2015 by Ian O'Neill

The Pluto Revolt: Leading Astronomers Want the Plutoid to be Reinstated as a Planet

Artist impression of Pluto and Charon (NASA)

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If you thought Pluto was going quietly and giving up its planetary status without a fight, think again. Leading astronomers have spoken out against the International Astronomical Union (IAU) decision to classify the dwarf planet as a “Plutoid,” described by some critics as a “celestial underclass.” The IAU decision was made after it was deemed that Pluto cannot be called a “planet.” Although the spherical rocky body can tick most attributes of being a “planet,” the IAU pointed out that Pluto is too small to be capable of gravitationally clearing its own orbit (plus it periodically crosses the path of Neptune’s orbit); it should therefore be called a “dwarf planet.” Back in June however, the IAU gloriously announced that Pluto should be now be re-classified as a “Plutoid” and any other Pluto-like planets should follow suit. But on Thursday, at a major conference in Maryland, leading astronomers will refute the Plutoid classification saying the IAU re-naming is confusing and unworkable…

It may be ~~the smallest planet in the Solar System~~ a Plutoid, but this little spherical rock is causing a lot of noise down here on Earth. In 2006, the IAU re-classified the definition of a planet to distinguish between the differences between the larger known planets with the smaller rocky bodies (such as the increasing number of observed Kuiper Belt objects). There are three defining characteristics of what a planet should be:

It is in orbit around the Sun.
It has sufficient mass so that it assumes a hydrostatic equilibrium (nearly round) shape.
It has “cleared the neighbourhood” around its orbit.

Pluto fulfils #1 and #2, but fails on #3, it is simply too small to gravitationally clear its own orbit. So Pluto was caught right in the middle of the “planetary classification debate ’06” and incidentally failed on one count. If any object fulfils the first two planetary criteria, but fails on the last, the IAU would classify the celestial body as a “dwarf planet.” To complicate matters, Pluto also travels inside the orbit of the gas giant Neptune periodically, giving it the extra classification of being a Trans-Neptunian Object (TNO). Although Pluto is a “dwarf” by Solar System standards, it is one of the largest Kuiper Belt Objects (KBO) in the outer Solar System; a true King amongst dwarfs.

Pluto has had a hard few months after getting kicked out of the planetary club.

So, for two years, Pluto was stuck in no-man’s land. It had been re-classified as a dwarf planet and astronomy teachers had to re-write their teaching material. Websites like NinePlanets.org had to scrub the 9 and replace it with an 8; but also had the foresight to buy “EightPlanets.org.” Times were a little messy for Pluto. Then, in June this year, the IAU seemed to want Pluto to feel a little better. Not only was it the King of the Kuiper Belt, it would have an entire army of Pluto-like dwarf planets named after it. The IAU created the “Plutoid,” and as if to avoid any more confusion, it gave the classification a no-nonsense definition:

Plutoids are celestial bodies in orbit around the Sun at a semi major axis greater than that of Neptune that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (near-spherical) shape, and that have not cleared the neighbourhood around their orbit. Satellites of plutoids are not plutoids themselves. – The IAU definition of a Plutoid (June 11th 2008).

Got that? Good. But not everyone was happy, least of all Pluto. T-shirts have even been printed with the quote: “It’s okay Pluto, I’m not a planet either” (and yes, I have one), for anyone wanting to show their support for the struggling rocky body.

So this Thursday, some very prominent astronomers will take their case to the “The Great Planet Debate: Science as Process” conference at The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. To cut a long story short, they want Pluto to be reinstated as a planet, thereby abandoning the term “Plutoid.”

Dr David Morrison, director of the NASA Lunar Science Institute in California, makes the point that if the largest planets in our Solar System can be called Gas “Giants” then it should be fine to call Pluto a “Dwarf” Planet. But in the current IAU classification, Pluto cannot be called a planet.

“It has never before been necessary for any organisation to define a word that has been in common every day use so I see no reason why it was necessary on this occasion. Astronomers use adjectives such as giant and dwarf to describe different subclasses of objects like planets, stars and galaxies, so why could Pluto not remain as a dwarf planet just as Jupiter is a giant planet. Also, around 90 per cent of the planets we know now are outside our solar system, but under the International Astronomical Unionâ€™s definition, they cannot be classed as planets.” – Dr David Morrison

So it would seem the classification of “planet” will remain a very exclusive club of eight under the IAU rules; only Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune will have this honour unless the scientists at the Great Planet Debate conference can convince the IAU otherwise. Mark Sykes, from the Planetary Science Institute, argues that only #2 of the IAU planet definition need be applied; it is therefore the shape, or roundness, of the object that defines whether it can be called a planet or not. If this definition were applied, the Solar System would expand to include 12 planets. This worries some traditional thinkers at the IAU. As our observational techniques improve, more planet candidates will be discovered, therefore making the Solar System wildly different than what it is now.

But if there are more “planets” out there, why shouldn’t more planets be added to the official eight we currently have? It sounds like the Pluto debate is far from over and it will be interesting to hear what the delegates have to say on Thursday…

Source: Telegraph

June 19, 2008December 24, 2015 by Ian O'Neill

2012: Planet X is not Nibiru

The Solar System’s outer reaches still contain many minor planets yet to be discovered. Ever since the search for Planet X began in the early 20th Century, the possibility of a hypothetical planet orbiting the Sun beyond the Kuiper Belt has fuelled many Doomsday theories and speculation that Planet X is actually the Sun’s long lost binary sibling. But why the fear about the Planet X/Doomsday combination? Surely Planet X is just an unknown, hypothetical object and nothing sinister?

Related 2012 articles:

As I’ve previously discussed in “2012: No Planet X“, doomsayers have linked the modern day search for Planet X, the ancient Mayan 2012 Prophecy and the Sumerian mythical planet Nibiru, culminating in bad news for December 21st 2012. However, the astronomical evidence for these links is seriously flawed.

Yesterday (Wednesday, June 18th), Japanese researchers announced news that their theoretical search for a large mass in the outer Solar System has produced results. From their calculations, there might just be a planet, possibly a bit bigger than a Plutoid but certainly smaller than Earth orbiting beyond 100 AU from the Sun. But before we get carried away, this is not Nibiru, this is not proof of the end of the world in 2012; it is a new and very exciting development in the search for minor planets beyond the Kuiper Belt…

In a new theoretical simulation, two researchers have deduced that the outermost reaches of the Solar System may contain an undiscovered planet. Patryk Lykawka and Tadashi Mukai of Kobe University have published a paper in the Astrophysical Journal detailing a minor planet that they believe may be interacting with the mysterious Kuiper Belt.

Kuiper Belt Objects (KBOs)

The Kuiper Belt occupies a huge region of space, approximately 30-50 AU from the Sun. It contains a vast number of rocky and metallic objects, the largest known body being the dwarf planet (or “Plutoid”) Eris. It has been known for many years that the Kuiper Belt has a few strange characteristics that may signal the presence of another large planetary body orbiting the Sun beyond the Kuiper Belt. One such feature is the aptly named “Kuiper Cliff” that occurs at 50 AU. This is an abrupt end to the Kuiper Belt, very few Kuiper Belt objects (or KBOs) have been observed beyond this point. This cliff cannot be attributed to orbital resonances with massive planets such as Neptune, and there doesn’t appear to be any obvious observational error. Many astronomers believe that such a sharp cut-off in KBO population may be due to an as-yet to be discovered planet, possibly as large as Earth. This is an object Lykawka and Mukai believe they have calculated to exist.

This research predicts a large object, 30-70% the mass of the Earth, orbiting at a distance of around 100-200 AU from the Sun. This object may also help explain why some KBOs and tran-Neptunian objects (TNOs) have some strange orbital characteristics (such as Sedna).

Ever since Pluto was discovered in 1930, astronomers have been looking for another more massive body that could explain the orbital perturbations observed in the orbits of Neptune and Uranus. This search became known as the “search for Planet X”, which literally meant the “search for an as yet unidentified planet.” In the 1980’s these perturbations were put down to observational error. Therefore, the modern-day scientific search for Planet X is the search for a large KBO or a minor planet beyond. Although Planet X may not be larger than the mass of the Earth, researchers are still very excited about finding more KBOs, possibly the size of a Plutoid, possibly a little bigger, but not much bigger.

“The interesting thing for me is the suggestion of the kinds of very interesting objects that may yet await discovery in the outer solar system. We are still scratching the edges of that region of the solar system, and I expect many surprises await us with the future deeper surveys.” – Mark Sykes, Director of the Planetary Science Institute in Arizona.

Planet X is not scary

So where does Nibiru come in? Back in 1976 a controversial book called “The Twelfth Planet” was written by Zecharia Sitchin. Sitchin had interpreted some ancient Sumerian cuneiform texts (the earliest known form of writing) as a literal translation of the origin of humankind. These 6000 year old texts apparently reveal that an alien race known as the Annunaki travelled to Earth on a planet called Nibiru. It’s a long and involved story, but in a nutshell, the Anunnaki genetically modified primates on Earth to create homo sapiens to be their slaves. (I just worked out where the storyline for Kurt Russell’s 1994 movie Stargate probably came from…)

When the Anunnaki left Earth, they let us rule the planet until they return. All this may seem a little fantastical, and perhaps a little too detailed when considering it is a literal translation from 6000 year old texts. Sitchin’s work has been disregarded by the scientific community as many of his methods of interpretation are considered imaginative at best. Nevertheless, many people have taken Sitchin’s work literally, and believe Nibiru (in its highly eccentric orbit around the Sun) will be returning, possibly as soon as 2012 to cause all sorts of terror and destruction here on Earth. It is important to note here that I am not calling into question any archaeological, spiritual or historic evidence for Nibiru, I am simply pointing out the link between the 2012 Doomsday Planet X theory is based on very dubious astronomical “discoveries”; if this is the case, how can Planet X be considered to be the embodiment of Nibiru?

Then there’s the IRAS “discovery of a brown dwarf in the outer Solar System” in 1984 and the “NASA announcement of a 4-8 Earth mass planet travelling toward Earth” in 1993. Doomsayers (often with a book to sell) cling on to these astronomical discoveries as proof that Nibiru is in fact the Planet X astronomers have been searching for over the last century. Not only that, by manipulating the facts about these scientific studies, they “prove” that Nibiru is travelling toward us, and by 2012, this massive body will pass through the inner Solar System, causing all sorts of gravitational damage. For more information on this topic, see “2012: No Planet X.”

In its purest form, Planet X is an unknown, theoretically possible planet orbiting peacefully beyond the Kuiper Belt. If yesterday’s announcement does lead to the observation of a planet or Plutoid, it will be an incredible discovery that will help to shed some light on the evolution and characteristics of the mysterious outer reaches of the Solar System.

But as I write, I can guarantee that doomsayers are adapting this new research to be used as support for their nonsensical theories that Planet X is in fact Nibiru, and it’s coming in our direction by 20 12 2012. Why do I get the feeling we’ll still be here in the year 2013?

Leading image credits: MIT (supernova simulation), NASA (Pluto and Charon). Effects and editing: myself.

February 26, 2008December 26, 2015 by Ian O'Neill

Pluto’s Moons, Nix and Hydra, may have been Adopted

The discovery images of Nix (and Hydra) obtained by the Hubble Space Telescope. Credit: NASA, ESA, H. Weaver (JHU/APL), A. Stern (SwRI)

How many moons does Pluto have? The mini-moons of Pluto, Nix and Hydra, were discovered in 2005 (but named in 2006) during an observation campaign by the Hubble Space Telescope. The discovery of these mini-moons increase the number of natural satellites orbiting Pluto to three (including larger moon Charon). But where did these satellites come from? The current accepted theory on the formation on the large moon, Charon, is much like the theory supporting the creation of Earth’s Moon. It is thought that a large impact between two Large Kuiper Belt Objects chipped Charon away from a proto-Pluto, putting the chunk of Pluto mass into orbit. Over the years, tidal forces slowed the pair and Charon was allowed to settle into its present-day orbit. Recent theory suggests that Nix and Hydra are a by product of this collision, merely shattered fragments of the huge impact. But there are problems with this idea. Could Nix and Hydra have come from somewhere other than the Pluto-Charon impact?

The small moons that orbit the Large Kuiper Belt Object (formerly classified as a planet) can be found about 48,700 kilometers and 64,800 kilometers from the surface of Pluto. The closest moon is called Nix and the farthest, Hydra. Nix has an orbital resonance of 4:1 with Charons orbit and the larger moon Hydra has a resonance of 6:1 (i.e. Nix will orbit Pluto once for every four of Charons orbits; Hydra will orbit Pluto once for every six of Charons orbits).

The reasons behind these mini-moon orbits are only just beginning to be understood, but it is known that their resonances with Charons orbit is rooted way back during the Pluto-system evolution. If we assume Hydra and Nix were formed from a massive Kuiper Belt Object collision, the easiest explanation is to assume they are whole fragments from the impact caught in the gravity of the Pluto-Charon system. However, due to the highly eccentric orbits that would have resulted from this collision, it is not possible that the two little moons could have evolved into a near-circular orbit, in near-corotational resonance with Charon.

So, could it be possible that the moons may have formed from the dust and debris resulting from the initial collision? If there was enough material produced, and if the material collided frequently, then perhaps Nix and Hydra were born from a cold disk of debris (rather than being whole pieces of rock), eventually coalescing and forming sizeable rocky moons. As there may have been a disk of debris, collisions with the orbiting Nix and Hydra would have also reduced any eccentricity in their orbits.

But there is a big problem with this theory. From impact simulations, the post-impact disk of debris surrounding Pluto would have been very compact. The disk could not have reached as far as the present-day orbits of the moons.

One more theory suggests that perhaps the moons were created in a post-impact disk, but very close to Pluto, and then through gravitational interactions with Charon, the orbits of Nix and Hydra were pulled outward, allowing them to orbit far from the Pluto-Charon post-impact disk. According to recent computer simulations, this doesn’t seem to be possible either.

To find an answer, work by Yoram Lithwick and Yanqin Wu (University of Toronto) suggest we must look beyond the Pluto-Charon system for a source of material for Nix and Hydra. From simulations, the above theories on the creation of the small moons being started by material ejected from a large collision between two Large Kuiper Belt Objects (creating Pluto and Charon) are extremely problematic. They do not correctly answer how the highly eccentric orbits Nix and Hydra would have from a collision could evolve into the near-circular ones they have today.

Lithwick and Wu go on to say that the circular, corotational resonant orbits of the two moons could be created from a Plutocentric disk of small bits of rock scooped up during Plutoâ€™s orbit around the Sun. Therefore Nix and Hydra may have been formed from the rocky debris left over from the development of the Solar System, and not from a collision event creating Charon. This may hold true for the countless other Kuiper Belt Objects in orbit in the far reaches of the Solar System, no impact is necessary for the creation of the tiny moons now thought to be their satellites.

It is hoped that the New Horizons mission (launched January 21st, 2006) to the far reaches of the Solar System will reveal some of the questions that remain unanswered in the depths of our mysterious Kuiper Belt. Hopefully we will also find out whether Nix and Hydra are children of Pluto and Charon… or whether they were adopted.

Source: arXiv

November 26, 2007December 26, 2015 by Astronomy Cast

Podcast: Pluto and the Icy Outer Solar System

It’s been a long journey, 64 episodes, but now we’re back where we began: Pluto. Last time we talked about how Pluto lost its planethood status, so we won’t go over all that again. This time we’re going to talk about Pluto, its moons, the Kuiper belt, and the other icy objects that inhabit the outer Solar System.
Click here to download the episode

Pluto and the Icy Outer Solar System – Show notes and transcript

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Go here if you’d like some Pluto pictures.