The mysterious Eris and moon Dysnomia (NASA)
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?
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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:
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This object is a stowaway on board New Horizons. Credit: JHU/APL
The New Horizons spacecraft has now spent over 1,000 days wending its way to Pluto and the Kuiper Belt. To celebrate the milestone, the New Horizons team decided to reveal the secret stowaways on board the spacecraft. Nine objects (can you guess why there are nine?!) were attached and sent along on the ten-year journey to the outer reaches of our solar system. Believe it or not, included in the items are one actual person, and parts of several thousands of other people…
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Artist rendition of New Horizons in the Kuiper Belt. Credit: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)
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 spacecraft’s Command and Data Handling system. “Our ‘brain transplant’ was a success,†says New Horizons Principal Investigator Alan Stern. “The new software – which guides how New Horizons carries out commands and collects and stores data – is now on the spacecraft’s main computer and operating, over a billion miles from home!â€
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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.
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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…
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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…
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Question: Why do some scientists consider Pluto to Not Be a Planet?
Answer: Since its discovery in 1930 until 2006, Pluto was considered a planet, just like the others in the Solar System. But in 2005, Caltech researcher Mike Brown announced that he had discovered a new object which was more distant, but larger in the Solar System.
This object was originally named 2003 UB313, but then was given the official designation of Eris, after the Greek God of strife and discord. It briefly had the nickname Xena - yes, after the TV show.
With the discovery of Eris, astronomers had to reconsider their definition of a planet. Since Eris is larger than Pluto, the number of planets in the Solar System would need to be expanded to 10. And who knows how much larger it would become with future discoveries.
The International Astronomical Union met in Prague in 2006 to make a final decision. They decided that a planet must fulfill three criteria:
It's this 3rd part where Pluto falls down. Pluto has only a fraction of the mass of the rest of the objects in its orbit, while the rest of the planets have essentially cleared theirs out completely. Does Pluto have moons? It does, but even with the mass of its moons, Pluto still doesn't dominate its orbit.
Pluto, Eris and the Asteroid Ceres were given the new designation of "dwarf planet".
I go into this in much more detail with the article, Why is Pluto Not a Planet?
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This has got to be be one of the most heartbreaking questions I get asked, "Why Isn't Pluto a Planet". And I get it a lot. I was expecting that a few years after the International Astronomical Union's controversial decision, the debate would have settled down and people would finally accept it. But no, it's still a sore point for many people - Pluto is not a planet (let that sink in). In this article, I'll explain the events that led up to the decision, the current state of planetary definition, and any hope Pluto has for the future. Let's find out why Pluto is no longer considered a planet.
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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?
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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
Or subscribe to: astronomycast.com/podcast.xml with your podcatching software.
Go here if you'd like some Pluto pictures.
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It's only been a few months since the discovery of ice geysers on Saturn's moon Enceladus, and now this dynamic process is turning up all over the Solar System. Astronomers think they've found a similar phenomenon on one of the strangest places: welling up from the surface of Pluto's moon Charon.
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For those of you hoping that Pluto the dwarf planet would get its full planethood status restored again, the news isn't looking good. The most recent observations peg the newly discovered dwarf planet Eris as being 27% more massive. And if Pluto is a planet again, shouldn't the even larger Eris get to be a planet too? Should we have 8 planets, or 10 or 20? Oh, it's madness.
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Although its primary target will be Pluto, NASA's New Horizons spacecraft is taking the time to do a little science along the way. During its recent Jupiter flyby, the spacecraft was able to test out its scientific instruments as a dress rehearsal for its final Pluto encounter. NASA held a big press conference this week, and released dozens of new images and scientific findings gathered by New Horizons.
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Even though New Horizon's Jupiter flyby happened weeks ago, scientists are only just starting to crunch through the data sent back. They're revealing better and better images of Jupiter, taken by the spacecraft's powerful instruments. The image attached to this story was taken using New Horizon's LEISA infrared camera. It's a false colour photograph - not what you'd actually see if you were looking at Jupiter - but the fine details in the image are impressive.
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While NASA's New Horizon spacecraft was making its gravity assisted flyby past Jupiter, some friends back at home were watching to help give the science some perspective. NASA's Hubble Space Telescope and the Chandra X-Ray Observatory gathered images of Jupiter for several days before the flyby, and the combined photographs were released today.
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Take a look at this photograph. See Pluto? It's that little orange speck. This photograph was taken by the Pluto-bound New Horizons spacecraft. Although Pluto is just a tiny dot today, it's going to get a lot bigger over the next 10 years when the spacecraft makes its close encounter in 2015. New Horizons used its Long Range Reconnaissance Imager (LORRI) to capture images of Pluto's region of space over several days. Scientists then analyzed the images, looking for an object moving at the right speed across several frames.
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Pluto. It's a planet, then it's not. This week we review Pluto's history, from discovery to demotion by the International Astronomical Union. Learn the 3 characteristics that make up a planet, and why Pluto now fails to make the grade.
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Although New Horizons is still more than 9 years away from reaching Pluto, it's ready to do some science along the way. The spacecraft passed an important milestone this week when it opened the protective cover on its Long Range Reconnaissance Imager (LORRI) and took a photograph of the Messier 7 star cluster. Stars were visible in this cluster down to 12th magnitude, which matches the instrument's pre-launch calibration. New Horizons will start imaging Jupiter with LORRI as it approaches a Feb. 28, 2007 flyby.
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Last year we had 9 planets. Recently we were informed it would grow to 12. Now we've only got 8. The International Astronomical Union, currently meeting in Prague, voted on August 24, 2006 to demote Pluto down from planethood status. Now Pluto, Charon, Ceres and the newly discovered 2003 UB313 (aka Xena) will merely be known as "dwarf planets". Under the new definition, planets must orbit a star, be spherical in shape, and clear out their neighbourhood of orbital debris. Pluto has failed to fulfill the third requirement, so it's official - Pluto is not a planet.
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The International Astronomical Union, currently meeting in Prague, has announced a proposal that would boost the number of planets in the Solar System to 12. Under their new classification, the asteroid Ceres, Pluto's moon Charon, and the newly discovered UB313 (aka Xena) would join the traditional 9 planets we're familiar with. Any additional large bodies would also be described as planets. The IAU will make a final vote on this proposal on August 24.
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The International Astronomical Union approved new names for Pluto's recently discovered tiny moons. Previously designated S/2005 P 1 and 2, the moons will now bear the names Hydra and Nix. In mythology, Nix is the goddess of darkness and night, while the hydra is a monster with the body of a serpent and nine heads. Although they're faint dots right now, NASA's New Horizons probe will fly pas them in 2015, and map them in much more detail.
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Pluto has been considered a planet since its discovery, but this position has come under threat with the discovery of 2003 UB313 (aka Xena), an object larger than Pluto orbiting out further in the Solar System. The International Astronomical Union will be meeting in August to decide on the fate of Pluto. By September, we could have 8 or 10 planets in the Solar System, but there won't be 9 any more.
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Still a decade away from its final meeting with Pluto, New Horizons tested out its instruments on a relatively nearby asteroid. The spacecraft turned its Multispectral Visible Imaging Camera (MVIC) on asteroid 2002 JF56 at a range of 1.34 to 3.36 million kilometers (about 833,000 to 2.1 million miles). Controllers were happy to see that the camera system was able to track the asteroid while the spacecraft was moving so quickly; it'll need this capability when it reaches Pluto. Its next stop will be Jupiter, which it's due to encounter on February 28, 2007.
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An artist's illustration of Xena with its moon. Image credit: NASA Click to enlarge
The powerful Hubble Space Telescope has finally been brought to bear on the newly discovered 10th planet (aka Xena), to help answer the question: is it really bigger than Pluto? Hubble is the only instrument that can make an actual visible light observation of Xena's diameter. Hubble found that Xena is is about 2400 km (1,490 miles) across, which makes it only 113 km (70 miles) larger than Pluto. This makes the 10th planet unusually bright, probably covered in brilliant white methane snow.
For the first time, NASA's Hubble Space Telescope has seen distinctly the "tenth planet," currently nicknamed "Xena," and has found that it is only slightly larger than Pluto.
Though previous ground-based observations suggested that Xena's diameter was about 30 percent greater than Pluto, Hubble observations taken Dec. 9 and 10, 2005, showed Xena's diameter as 1,490 miles (with an uncertainty of 60 miles). Pluto's diameter, as measured by Hubble, is 1,422 miles.
"Hubble is the only telescope capable of getting a clean visible-light measurement of the actual diameter of Xena," said Mike Brown, planetary scientist at the California Institute of Technology in Pasadena, Calif. Brown's research team discovered Xena, officially cataloged as 2003 UB313, and its results have been accepted for publication in the Astrophysical Journal.
Only a handful of images were required to determine Xena's diameter. Located 10 billion miles from Earth with a diameter a little more than half the width of the United States, the object is 1.5 pixels across in Hubble's view. That's enough to make a precise size measurement.
Because Xena is smaller than previously thought, but comparatively bright, it must be one of the most reflective objects in the solar system. The only object more reflective is Enceladus, a geologically active moon of Saturn whose surface is continuously recoated with highly reflective ice by active geysers.
Xena's bright reflectivity is possibly due to fresh methane frost on its surface. The object may have had an atmosphere when it was closer to the sun, but as it moved to its current location farther away this atmosphere would have "frozen out," settling on the surface as frost.
Another possibility is that Xena leaks methane gas continuously from its warmer interior. When this methane reaches the cold surface, it immediately freezes solid, covering craters and other features to make it uniformly bright to Hubble's telescopic eye.
Xena's takes about 560 years to orbit the sun, and it is now very close to aphelion (the point on its orbit that is farthest from the sun).Brown next plans to use Hubble and other telescopes to study other recently discovered Kuiper Belt objects that are almost as large as Pluto and Xena. The Kuiper Belt is a vast ring of primordial icy comets and larger bodies encircling Neptune's orbit.
Finding that the largest known Kuiper Belt object is a virtual twin to Pluto may only further complicate the debate about whether to categorize the large icy worlds that populate the belt as planets. If Pluto were considered to be the minimum size for a planet, then Xena would fulfill this criterion, too. In time, the International Astronomical Union will designate the official name.
The Hubble Space Telescope is an international cooperative project between NASA and the European Space Agency. The Space Telescope Science Institute in Baltimore conducts Hubble science operations. The Institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington
For electronic images and more Hubble news, visit: http://www.nasa.gov/hubble
Original Source: NASA News Release
Update, Pluto is no longer a planet. Why is Pluto not a planet?
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