New 'planet' is larger than Pluto

[Celebration]

http://www.physorg.com/news10451.html

Claims that the Solar System has a tenth planet are bolstered by the finding by a group lead by Bonn astrophysicists that this alleged planet, announced last summer and tentatively named 2003 UB313, is bigger than Pluto. By measuring its thermal emission, the scientists were able to determine a diameter of about 3000 km, which makes it 700 km larger than Pluto and thereby marks it as the largest solar system object found since the discovery of Neptune in 1846 (Nature, 2 February 2006).


Like Pluto, 2003 UB313 is one of the icy bodies in the so-called Kuiper belt that exists beyond Neptune. It is the most distant object ever seen in the Solar System. Its very elongated orbit takes it up to 97 times farther from the Sun than is the Earth - almost twice as far as the most distant point of Pluto's orbit - so that it takes twice as long as Pluto to orbit the Sun. When it was first seen, UB313 appeared to be at least as big as Pluto. But an accurate estimate of its size was not possible without knowing how reflective it is. A team lead by Prof. Frank Bertoldi from the University of Bonn and the Max Planck Institute for Radio Astronomy (MPIfR) and the MPIfR's Dr. Wilhelm Altenhoff has now resolved this problem by using measurements of the amount of heat UB313 radiates to determine its size, which when combined with the optical observations also allowed them to determine its reflectivity. "Since UB313 is decidedly larger than Pluto," Frank Bertoldi remarks, "it is now increasingly hard to justify calling Pluto a planet if UB313 is not also given this status."


To detect the very faint millimeter wavelength emission from UB313, the Bonn group used the IRAM 30-m telescope on Pico Veleta in the south of Spain, and the very sensitive heat sensor MAMBO-2, which was developed and built at the MPIfR in Bonn by the group of Dr. Ernst Kreysa. The Institute for Radio Astronomy at Millimeter wavelengths (IRAM) is supported jointly by the German Max Planck Society, the French Centre National de Recherche Scientifique (CNRS) and the Spanish Instituto Geográfico Nacional. Image: Max Planck Institute for Radio Astronomy


UB313 was discovered in January 2005 by Prof. Mike Brown and his colleagues from the Californian Institute of Technology in a sky survey using a wide field digital camera that searches for distant minor planets at visible wavelengths. They discovered a slowly moving, spatially unresolved source, the apparent speed of which allowed them to determine its distance and orbital shape. However, they were not able to determine the size of the object, although from its optical brightness it was believed to be larger than Pluto.

[Richardo]

1. What isn't?

It's an interesting article, but the headline could use some work. :)

[ArbustoBuster]

2. Well, I'm not larger than Pluto.

And President Chimpy's brain is certainly not larger than Pluto.

Many things are smaller than Pluto!

(Extra credit if you read my post as if it was a children's science show.) :)

[mainegreen]

3. So, will this explain the Kuiper belt cliff?

Or do will still need to keep looking?