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TOPIC: 2003UB313 / The Tenth Planet


L

Posts: 131433
Date:
Dysnomia
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The satellite, now called Dysnomia, is named for Eris's daughter, the goddess of lawlessness — a tribute, says Brown, to the actress who played Xena, Warrior Princess: Lucy Lawless. But Brown is quick to point out that the moon also follows another tradition for "dwarf planet" satellite names: Pluto's moon Charon was discovered in 1978 by James W. Christy, and the first syllable in Charon matches the first syllable in Christy's wife's name, Charlene. Brown's wife's name is Diane.

"We're going to call the moon Di" - Michael E. Brown.

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Posts: 131433
Date:
(136199) Eris
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2003 UB313 (aka Xena) is now officially named (136199) Eris.
The moon, Gabrielle is now called Dysnomia.

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RE: 10th Planet
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Ephemeris:  	

2003 UB313 a,e,i = 67.71, 0.44, 44 q = 37.808
Date UT R.A. (J2000) Decl. Delta r El. Ph. V Sky Motion
h m s "/min P.A.
2006 08 25 000000 01 39 32.1 -05 08 56 96.219 96.858 129.0 0.5 18.7 0.016 235.4
2006 08 26 000000 01 39 30.9 -05 09 09 96.207 96.858 129.9 0.5 18.7 0.016 235.9
2006 08 27 000000 01 39 29.6 -05 09 22 96.194 96.858 130.8 0.5 18.7 0.016 236.4
2006 08 28 000000 01 39 28.3 -05 09 35 96.182 96.857 131.7 0.4 18.7 0.017 236.9
2006 08 29 000000 01 39 26.9 -05 09 48 96.171 96.857 132.6 0.4 18.7 0.017 237.4
2006 08 30 000000 01 39 25.5 -05 10 01 96.159 96.857 133.5 0.4 18.7 0.017 237.8
2006 08 31 000000 01 39 24.1 -05 10 14 96.147 96.857 134.4 0.4 18.7 0.017 238.2
2006 09 01 000000 01 39 22.7 -05 10 28 96.136 96.857 135.4 0.4 18.7 0.018 238.7
2006 09 02 000000 01 39 21.2 -05 10 41 96.125 96.857 136.3 0.4 18.7 0.018 239.1
2006 09 03 000000 01 39 19.7 -05 10 54 96.114 96.857 137.2 0.4 18.7 0.018 239.5
2006 09 04 000000 01 39 18.2 -05 11 08 96.104 96.856 138.1 0.4 18.7 0.019 239.8
2006 09 05 000000 01 39 16.6 -05 11 21 96.093 96.856 139.0 0.4 18.7 0.019 240.2
2006 09 06 000000 01 39 15.0 -05 11 34 96.083 96.856 139.9 0.4 18.7 0.019 240.6
2006 09 07 000000 01 39 13.4 -05 11 48 96.073 96.856 140.8 0.4 18.7 0.019 240.9
2006 09 08 000000 01 39 11.8 -05 12 01 96.063 96.856 141.7 0.4 18.7 0.020 241.3
2006 09 09 000000 01 39 10.1 -05 12 15 96.054 96.856 142.6 0.4 18.7 0.020 241.6
2006 09 10 000000 01 39 08.4 -05 12 28 96.045 96.856 143.5 0.4 18.7 0.020 241.9
2006 09 11 000000 01 39 06.7 -05 12 42 96.036 96.856 144.4 0.3 18.7 0.020 242.3
2006 09 12 000000 01 39 05.0 -05 12 56 96.027 96.855 145.2 0.3 18.7 0.020 242.6
2006 09 13 000000 01 39 03.2 -05 13 09 96.018 96.855 146.1 0.3 18.7 0.021 242.9
2006 09 14 000000 01 39 01.4 -05 13 23 96.010 96.855 147.0 0.3 18.7 0.021 243.2


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L

Posts: 131433
Date:
2003 UB313
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On August 24th 2006 the word "planet" was given its first-ever scientific definition by a vote of the International Astronomical Union. With the raising of a few yellow cards in Prague Pluto was demoted from full-fledged planet to "dwarf planet." The object 2003 UB313, sometimes called Xena, sometimes called the "10th planet," which in many ways precipitated this final debate, becomes the largest known dwarf planet. Unless astronomers revisit this issue at some point in the future, it is unlikely that there will ever be more than eight planets.

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L

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RE: 10th Planet
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The International Astronomical Union (IAU) today downgraded the status of Pluto to that of a "dwarf planet," a designation that will also be applied to the spherical body discovered last year by California Institute of Technology planetary scientist Mike Brown and his colleagues. The decision means that only the rocky worlds of the inner solar system and the gas giants of the outer system will hereafter be designated as planets.

The ruling effectively settles a year-long controversy about whether the spherical body announced last year and informally named "Xena" would rise to planetary status. Somewhat larger than Pluto, the body has been informally known as Xena since the formal announcement of its discovery on July 29, 2005, by Brown and his co-discoverers, Chad Trujillo of the Gemini Observatory and David Rabinowitz of Yale University. Xena will now be known as the largest dwarf planet.

"I'm of course disappointed that Xena will not be the tenth planet, but I definitely support the IAU in this difficult and courageous decision. It is scientifically the right thing to do, and is a great step forward in astronomy. Pluto would never be considered a planet if it were discovered today, and I think the fact that we've now found one Kuiper-belt object bigger than Pluto underscores its shaky status" - Mike Brown.

Pluto was discovered in 1930. Because of its size and distance from Earth, astronomers had no idea of its composition or other characteristics at the time. But having no reason to think that many other similar bodies would eventually be found in the outer reaches of the solar system--or that a new type of body even existed in the region--they assumed that designating the new discover as the ninth planet was a scientifically accurate decision.
However, about two decades later, the famed astronomer Gerard Kuiper postulated that a region in the outer solar system could house a gigantic number of comet-like objects too faint to be seen with the telescopes of the day. The Kuiper belt, as it came to be called, was demonstrated to exist in the 1990s, and astronomers have been finding objects of varying size in the region ever since.
Few if any astronomers had previously called for the Kuiper-belt objects to be called planets, because most were significantly smaller than Pluto. But the announcement of Xena's discovery raised a new need for a more precise definition of which objects are planets and which are not.
According to Brown, the decision will pose a difficulty for a public that has been accustomed to thinking for the last 75 years that the solar system has nine planets.

"It's going to be a difficult thing to accept at first, but we will accept it eventually, and that's the right scientific and cultural thing to do" - Mike Brown .

In fact, the public has had some experience with the demotion of a planet in the past, although not in living memory. Astronomers discovered the asteroid Ceres on January 1, 1801--literally at the turn of the 19th century. Having no reason to suspect that a new class of celestial object had been found, scientists designated it the eighth planet (Uranus having been discovered some 20 years earlier).
Soon several other asteroids were discovered, and these, too, were summarily designated as newly found planets. But when astronomers continued finding numerous other asteroids in the region (there are thought to be hundreds of thousands), the astronomical community in the early 1850s demoted Ceres and the others and coined the new term "asteroid."

Xena was discovered on January 8, 2005, at Palomar Observatory with the NASA-funded 48-inch Samuel Oschin Telescope. Xena is about 2,400 kilometres in diameter. A Kuiper-belt object like Pluto, but slightly less reddish-yellow, Xena is currently visible in the constellation Cetus to anyone with a top-quality amateur telescope.
Brown and his colleagues in late September announced that Xena has at least one moon. This body has been nicknamed Gabrielle, after Xena's sidekick on the television series.
Xena is currently about 97 astronomical units from the sun (an astronomical unit is the distance between the sun and Earth), which means that it is some nine billion miles away at present. Xena is on a highly elliptical 560-year orbit, sweeping in as close to the sun as 38 astronomical units. Currently, however, it is nearly as far away as it ever gets.

Pluto's own elliptical orbit takes it as far away as 50 astronomical units from the sun during its 250-year revolution. This means that Xena is sometimes much closer to Earth than Pluto--although never closer than Neptune.
Gabrielle is about 250 kilometres in diameter and reflects only about 1 percent of the sunlight that its parent reflects. Because of its small size, Gabrielle could be oddly shaped.
Brown says that the study of Gabrielle's orbit around Xena hasn't yet been fully completed. But once it is, the researchers will be able to derive the mass of Xena itself from Gabrielle's orbit. This information will lead to new insights on Xena's composition.
Based on spectral data, the researchers think Xena is covered with a layer of methane that has seeped from the interior and frozen on the surface. As in the case of Pluto, the methane has undergone chemical transformations, probably due to the faint solar radiation, that have caused the methane layer to redden. But the methane surface on Xena is somewhat more yellowish than the reddish-yellow surface of Pluto, perhaps because Xena is farther from the sun.

Brown and Trujillo first photographed Xena with the 48-inch Samuel Oschin Telescope on October 31, 2003. However, the object was so far away that its motion was not detected until they reanalysed the data in January of 2005.

Source

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L

Posts: 131433
Date:
Definition of a Planet
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Draft Resolution 5 for GA-XXVI: Definition of a Planet

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L

Posts: 131433
Date:
Xena
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According to the new draft definition, by the International Astronomical Union (IAU), two conditions must be satisfied for an object to be called a "planet." First, the object must be in orbit around a star, while not being itself a star. Second, the object must be large enough (or more technically correct, massive enough) for its own gravity to pull it into a nearly spherical shape. The shape of objects with mass above 5 x 10^20 kg and diameter greater than 800 km would normally be determined by self-gravity, but all borderline cases would have to be established by observation.

If the proposed Resolution is passed, there will be 12 planets in our Solar System; Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Charon and 2003 UB313. The name 2003 UB313 is provisional, as a "real" name has not yet been assigned to this object. A decision and announcement of a new name are likely not to be made during the IAU General Assembly in Prague, but at a later time. The naming procedures depend on the outcome of the Resolution vote. There will most likely be more planets announced by the IAU in the future. Currently a dozen "candidate planets" are listed on IAU's "watchlist" which keeps changing as new objects are found and the physics of the existing candidates becomes better known.

The draft "Planet Definition" Resolution will be discussed and refined during the General Assembly and then it (plus four other Resolutions) will be presented for voting at the 2nd session of the GA 24 August between 14:00 and 17:30 CEST.

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Posts: 131433
Date:
RE: 10th Planet
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Officials with the National Astronomical Observatories of Chinese Academy of Sciences (NAOC) revealed that the International Astronomical Union (IAU) General Assembly is to be held in Czech Republic in August this year and will give answers to whether or not there is a 10th planet in the solar system and whether or not Pluto, the 9th planet, belongs to the solar system, which are two fiercely debated issues in the astronomical community in recent years. During the meeting, over 2,000 astronomers from all over the world, including China will cast votes on a complete scientific definition of "planet" which is closely related to the family membership of the solar system.

Li Jing, a researcher in NAOC said in an interview that Mike Brown, an American scientist discovered a celestial body on the verge of the solar system in 2003 and declared it is the 10th planet in the solar system in 2005. The announcement sparked off heated debates over the existence of the 10th planet and the validity of Pluto's membership in the solar system, which has reasonably become the discussion topic for this year's IAU General Assembly. A subcommittee of IAU will prepare a formula for the definition of planet. The formula will be handed to the conference, and discussed and approved by the astronomers through voting. The astronomers' decision will give clear answers to how to define a "planet" and how many planets there are in the solar system.

According to Li Jing, most of Chinese astronomers and part of their foreign counterparts do not think the so-called 10th planet "Xena" and even Pluto are true planets. These two celestial bodies do not follow the rules of planet. Instead they are objects inside the Kuiper Belt that is vast population of ice bodies extending beyond the orbit of Neptune. Thus in fact, the solar system contains only 8 planets. But in as early as 1930, Pluto was put into textbooks as the 9th planet in the solar system. For this historical reason, it is very unlikely that Pluto will be deprived of its membership in the solar system family. But those celestial bodies discovered recently or to be found in the future inside the solar system will not be called planets by any name if they do not fit the scientific definition of "planet". Nevertheless, some astronomers think that "Xena" is the largest object found beyond the orbit of Pluto and qualifies as the 10th planet because of its size.

Source People's Daily

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L

Posts: 131433
Date:
Xena
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Astronomers are expected to add at least one new planet to the nine already known to exist in our solar system.

The new body, provisionally named Xena, is nine billion miles from the Sun, about 100 times more distant than the Earth and well beyond Pluto.
Its diameter is 1,490 miles, 70 miles greater than that of Pluto, the smallest and most distant planet, which may qualify it for planetary status.
The decision will be taken next month at a meeting of the International Astronomical Union (IAU) in Prague when 2,000 astronomers will be asked to vote on the “expansion” of the solar system.

Xena is the largest of many similar bodies recently found in orbits beyond Pluto. Some astronomers argue that declaring them all planets will devalue the term. Others warn that a scientifically “purist” approach would mean stripping Pluto of its planetary status — which could be deeply unpopular with the public.

"We have been seeking a compromise solution" - Iwan Williams, professor of mathematics and astronomy at Queen Mary, University of London, who chairs a committee set up by the IAU to define what a planet is.

Its report will be presented to the IAU next month. Williams has not disclosed his precise proposals but said:

"We had to decide whether to stick to a purely scientific approach or to consider other aspects such as culture and history"

Some astronomers believe that the term “planet”should be limited to the four rocky orbs, Mercury, Venus, Earth and Mars, and the four gas giants, Jupiter, Saturn, Uranus and Neptune.
Pluto was accepted as the ninth planet only because Clyde Tombaugh, who discovered it in 1930, misjudged its size, claiming that it was larger than Earth. Its actual mass is 400 times less.
By the time the mistake had been corrected, Pluto had entered the textbooks as the only planet to have been discovered by an American. Any attempt to question its status since then has been fiercely opposed by American scientists.
Professor Brian Marsden, a Briton who directs the minor planet centre at the Harvard Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, says US astronomers threatened to throw him into a hotel swimming pool after a 1980 conference where he called for Pluto to be reclassified as an asteroid.

"This issue has been overlooked for far too long. The term planet should have a proper scientific definition" - Professor Brian Marsden.

Source

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L

Posts: 131433
Date:
Ephemeris
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Ephemeris:


2003 UB313 a,e,i = 67.71, 0.44, 44 q = 37.808
Date TT R. A. (2000) Decl. Delta r Elong. Phase V
2005 07 29 01 39.38 -05 19.3 96.681 96.939 104.4 0.6 18.9
2005 08 08 01 39.30 -05 21.0 96.526 96.937 113.7 0.5 18.9
2005 08 18 01 39.16 -05 22.9 96.382 96.936 122.9 0.5 18.9
2005 08 28 01 38.97 -05 25.0 96.254 96.934 132.1 0.4 18.8
2005 09 07 01 38.72 -05 27.3 96.146 96.933 141.2 0.4 18.8
2005 09 17 01 38.42 -05 29.5 96.061 96.932 149.9 0.3 18.8
2005 09 27 01 38.10 -05 31.8 96.001 96.930 157.9 0.2 18.8
2005 10 07 01 37.74 -05 33.9 95.968 96.929 163.9 0.2 18.8
2005 10 17 01 37.37 -05 35.8 95.965 96.928 165.0 0.2 18.8
2005 10 27 01 37.00 -05 37.4 95.990 96.926 160.3 0.2 18.8
2005 11 06 01 36.64 -05 38.7 96.043 96.925 152.7 0.3 18.8
2005 11 16 01 36.30 -05 39.6 96.124 96.924 143.8 0.3 18.8
2005 11 26 01 35.99 -05 40.1 96.229 96.922 134.4 0.4 18.8
2005 12 06 01 35.72 -05 40.1 96.355 96.921 124.8 0.5 18.8
2005 12 16 01 35.50 -05 39.6 96.499 96.919 115.0 0.5 18.9
2005 12 26 01 35.34 -05 38.7 96.656 96.918 105.2 0.6 18.9
2006 01 05 01 35.25 -05 37.3 96.821 96.917 95.3 0.6 18.9
2006 01 15 01 35.22 -05 35.4 96.988 96.915 85.4 0.6 18.9
2006 01 25 01 35.26 -05 33.2 97.154 96.914 75.6 0.6 18.9
2006 02 04 01 35.36 -05 30.7 97.311 96.913 65.9 0.5 18.9
2006 02 14 01 35.53 -05 27.9 97.457 96.911 56.2 0.5 18.9
2006 02 24 01 35.75 -05 25.0 97.586 96.910 46.7 0.4 18.9
2006 03 06 01 36.03 -05 21.9 97.694 96.908 37.5 0.4 18.9
2006 02 27 01 35 49.9 -05 24 03 97.594 96.882 43.9 0.4 18.8
2006 02 28 01 35 51.5 -05 23 45 97.605 96.882 43.0 0.4 18.8
2006 03 01 01 35 53.2 -05 23 26 97.616 96.882 42.0 0.4 18.8
2006 03 02 01 35 54.9 -05 23 08 97.626 96.882 41.1 0.4 18.8
2006 03 03 01 35 56.6 -05 22 49 97.637 96.882 40.2 0.4 18.8
2006 03 04 01 35 58.3 -05 22 31 97.647 96.882 39.3 0.4 18.8
2006 03 05 01 36 00.0 -05 22 12 97.657 96.882 38.4 0.4 18.8
2006 03 06 01 36 01.8 -05 21 54 97.667 96.881 37.5 0.4 18.8
2006 03 07 01 36 03.6 -05 21 35 97.677 96.881 36.6 0.3 18.8
2006 03 08 01 36 05.4 -05 21 17 97.686 96.881 35.7 0.3 18.8
2006 03 09 01 36 07.3 -05 20 58 97.695 96.881 34.8 0.3 18.8
2006 03 10 01 36 09.2 -05 20 40 97.704 96.881 33.9 0.3 18.8
2006 03 11 01 36 11.1 -05 20 21 97.713 96.881 33.0 0.3 18.8
2006 03 12 01 36 13.0 -05 20 03 97.721 96.881 32.1 0.3 18.8
2006 03 13 01 36 14.9 -05 19 44 97.729 96.881 31.2 0.3 18.8
2006 03 14 01 36 16.9 -05 19 26 97.737 96.880 30.4 0.3 18.8
2006 03 15 01 36 18.9 -05 19 07 97.744 96.880 29.5 0.3 18.8
2006 03 16 01 36 20.9 -05 18 49 97.752 96.880 28.7 0.3 18.8
2006 03 17 01 36 22.9 -05 18 30 97.759 96.880 27.8 0.3 18.8
2006 03 18 01 36 25.0 -05 18 12 97.766 96.880 27.0 0.3 18.7
2006 03 19 01 36 27.0 -05 17 54 97.772 96.880 26.2 0.3 18.7


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