Pluto again..

> -----Original Message-----
> From: mpml@yahoogroups.com [mailto:mpml@yahoogroups.com] On
> Behalf Of Ron Baalke
> Sent: Thursday, June 14, 2007 11:59 AM
> To: Minor Planet Mailing List
> Subject: {MPML} The Dwarf Planet Known as Eris is Bigger,
> More Massive than Pluto, New Data Shows
>
>
> Caltech News Release
> Embargoed until 11:00 AM PDT, Thursday, June 14, 2007
>
> The Dwarf Planet Known as Eris is Bigger, More Massive than Pluto,
> New Data Shows
>
> PASADENA, Calif.--Die-hard Pluto fans still seeking redemption for
> their demoted planet have cause for despair this week. New data shows
> that the dwarf planet Eris is 27 percent more massive than Pluto,
> thereby strengthening the decree last year that there are eight
> planets in the solar system and a growing list of dwarf planets.
>
> According to Mike Brown, the discoverer of Eris, and his graduate
> student Emily Schaller, the data confirms that Eris weighs 16.6
> billion trillion kilograms. They know this because of the time it
> takes Eris's moon, Dysnomia, to complete an orbit.
>
> "This was Pluto's last chance to be the biggest thing found so far in
> the Kuiper belt," says Brown, a professor of planetary astronomy at
> the California Institute of Technology. "There was a possibility that
> Pluto and Eris were roughly the same size, but these new results show
> that it's second place at best for Pluto."
>
> Eris was discovered in 2005 with Palomar Observatory's 48-inch Samuel
> Oschin Telescope, an instrument specially adapted to do comprehensive
> searches for objects in the sky.
>
> When it became apparent that Eris was similar in size if not larger
> than Pluto, Brown and others called for the International
> Astronomical Union to rule on its planetary status. The end result
> was demotion of Pluto and the redesignation of it and other
> Kuiper-belt objects as dwarf planets.
>
> Schaller says that the new results, obtained with Hubble Space
> Telescope and Keck Observatory data, indicate that the density of the
> material making up Eris is about two grams per cubic centimeter. This
> means that Eris very likely is made up of ice and rock, and thus is
> very similar in composition to Pluto. Past results from the Hubble
> Space Telescope had already allowed planetary scientists to determine
> that its diameter is 2,400 kilometers, also larger than Pluto's.
>
> "Pluto and Eris are essentially twins--except that Eris is slightly
> the pudgier of the two," says Brown. "And a little colder," adds
> Schaller.
>
> The reason for Eris's blustery surface conditions is its sheer
> distance from the sun. Currently 97 astronomical units from the sun
> (an astronomical unit being the distance between the sun and Earth),
> Eris hovers at temperatures well below 400 degrees Fahrenheit and is
> pretty dark.
>
> However, things get a little better on Eris now and then. Orbiting
> the sun on a highly elliptical 560-year journey, Eris sweeps in as
> close to the sun as 38 astronomical units. But at present 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
> Eris is sometimes much closer to Earth than Pluto, although never
> closer than Neptune.
>
> Based on spectral data, the researchers think Eris 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, causing
> the methane layer to redden. But the methane surface on Eris is
> somewhat more yellowish than the reddish-yellow surface of Pluto,
> perhaps because Eris is farther from the sun.
>
> As for Dysnomia, the tiny satellite remains the only moon discovered
> orbiting Eris so far. Dysnomia is about 150 kilometers in diameter,
> is about 37,000 kilometers from Eris, and has a lunar "month" that
> lasts 16 days.
>
> "But every year is 560 Earth-years," says Brown. "So on Eris they
> have a lot more months in their calendar."
>
> Like the Earth-moon system, Eris-Dysnomia probably formed about 4.5
> billion years ago following a massive collision.
>
> Brown and Schaller are the authors of a paper, "The Mass of Dwarf
> Planet Eris," appearing in the June 15 issue of the journal Science.
>
> The search for new planets and other bodies in the Kuiper belt is
> funded by Caltech and NASA. For more information on the program, see
> the Samuel Oschin Telescope's website at
> http://www.astro.caltech.edu/palomarnew/sot.html.
>
> For more information on Mike Brown's research, see
> http://www.gps.caltech.edu/~mbrown.
>
> To learn more about Eris, see http://www.planeteris.com.
>
> Contact:
> Robert Tindol
> tindol@...
> (626) 395-3631
>
>
>
>
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