When astronomers announced the discovery of UB313, the so-called tenth planet, a little more than a year ago, they had a hunch it might be bigger than Pluto because of its brightness. But despite several attempts to observe more closely the mysterious object orbiting the sun at a distance of more than 14 billion kilometers, accurate estimates of its size remained elusive. Now German astronomers working in Spain have determined that UB313 has a diameter of roughly 3,000 kilometers--roughly 700 kilometers larger than Pluto's. Frank Bertoldi of the University of Bonn in Germany and his colleagues used the IRAM 30-meter telescope in the Sierra Nevada mountains of southern Spain to observe UB313 in the infrared range. Because visual brightness alone is not an accurate indicator of size--it could result from the body's surface being either actually large or mirrorlike--the researchers made observations in wavelengths longer than those of visible light. Outside the range of visible light, the scientists could measure the amount of light the object absorbs and then radiates back as heat. By combining the infrared and visible measurements, they could then determine the object's size and its overall reflectivity, or albedo.

Based on observations made over nine nights in August 2005, the team reports, UB313 appears to have a diameter of between 3,094 and 2,859 kilometers. Even the smallest size in that range would make the candidate planet's diameter more than 500 kilometers larger than Pluto's. These calculations rely on several assumptions, however, such as UB313 lacking an atmosphere that would either reflect more light or trap more heat even though Pluto has such a covering. The astronomers estimate that the planet reflects roughly the same amount of light as Pluto, perhaps thanks to an icy methane surface. Their research appears in today's issue of Nature.

View: Full Article | Source: Scientific American

Just one more place for use to live when the sun becomes a red giant!
There are probably many more such large Kuiper belt objects out there. At least we know that planets, or planet-like objects are not rare!

planet -like is right. there is dispute wether pluto is a planet at all ...so just because this object is larger then pluto doesn't make it a planet

That's why I used both terms. I certainly don't want to join in on the huge pissing contest that astronomers are having over that arguement!

They don't even HAVE a clear-cut definition for a planet. The terrestrial planets are so different from the Jovian planets that an argument could be made that one group or the other are not "true" planets.

The word "planet" is Greek for "Wanderer." Moving across the backdrop of "fixed" stars. By that definition everything that orbits sol is a planet.
Makes my head hurt.

As I understand these "Planetoids" are smaller than Earth's moon , and made of mostly ice and dust. Not much of interest and because of thier odd orbits not practical as a launch platform for Interstellar space.

Um...it's kinda funny that this "new Mystery Planet" happens to be just where the planet
Nibiru, mentioned in Zecharia Sitchin's books, is reported to be.

Show me the documentation where Nimbiru is predicted to be orbiting sol at 14,000,000,000km please...

I always knew there was something bigger than Pluto

It wasn't Uranus was it?

Sorry fella I just couldn't help it!


(This is not an inflammatory attack! I love all of you!)

Seeing that nobody else wants to name it.. i shall name it:

Daniel Land

lol

Interesting... they will have to change all the text books. Surely they cannot stick with the name UB313.

So is this planet bigger than Earth

If I remember correctly the new planet is slightly larger than Pluto and both are smaller than Earth's Moon!

Nibiru the 10th planet orbits our solar system every 3500years and passes Earth .Its been recorded in the Sumerien texts and the Bible The last time Nibiru passed it caused a great gravitational pool on Earth which was probably responsible for the Great flood in Noahs time .Scientists say that Nibiru is orbiting between 2005 -2007 which could explain the abnormal phenomina on Earth like higher temperatures, floods etc.Zacariah Stitchens work on Mesotopanamia persian greek and Egytian cultures all concur around the same ideology of a reptilien cold blooded race who married cross bread and enslaved man because their planet needed gold emeralds and many of Earths resources .I believe that theres a War in Heaven for control of Earth and that we are actually loosing as you see on the Tele so my advice is to follow your hearts and repent of thy works.

I think the Bush administration is behind this.

Then it must have a very high eccentricity more likely found in a cometary orbit than a planet.
Plausible, but many wild theories have at least one fact right. That is what makes them so seductive.
No.Again, plausilbe, same disclaimer.etc is not valid in scienceHow would a cold blooded race (depending on the heat of the sun for life, remember, this planet is roughly Earth's Moon in size, little chance for internal heat, yes Europa is warm but only because of tidal forces r/t Jupiter) evolve, let alone survive on a planet that spends most of it's 3500 year orbit beyond Pluto?

Also, a body the size of the Moon, approaching Perihelion, would be rapidly approaching the brightness of the full Moon, (on approach it would be superior and thus appear "full") where is it? Even if it is still beyond the orbit of Jupiter, it would be visible to the thousands of comet watchers and have a huge proper motion.

People, I too love the thought of mysteries in our universe but how will we ever be given serious consideration if we don't check our facts before proposing something that is so dismissable?