Hindu god points way to 10th solar planet

May 24, 2001

<h3>Hindu god points way to 10th solar planet</h3>

PARIS (AFP) May 23, 2001

A large asteroid, named Varuna after the lord of the cosmos in Hindu mythology, has been spotted in the outer fringes of the Solar System, a discovery which suggests the Sun may have more than nine planets, astronomers say.

Varuna was detected last November by Arizona-based astronomers in the Spacewatch Project, a scheme aimed at scouring the asteroid belts to look, in part, for rogue rocks that could be a potential threat to Earth.

The spherical object is 900 kilometers (550 miles) in diameter, which makes it only a tad smaller than Charon, the tiny moon (1,200 kms, 750 miles, across) that orbits Pluto, the most distant of the Sun's nine known planets.

The discovery, by a team led by David Jewitt of the Institute of Astronomy in Honolulu, is reported Thursday in Nature, the British science weekly.

Until 1992, Pluto and Charon were the only known objects in the Kuiper Belt, an ancient ring of icy bodies believed to be have been formed from the outer reaches of material that swirled around the infant Sun billions of years ago.

Since then, more than 400 other Kuiper Belt objects have been discovered by powerful telescopes.

But astronomers suspect the belt could hold hundreds of thousands of rocks 100 kms (60 miles) across, and possibly billions of others 10 kms (six miles) across.

The biggest handicap to identifying them has been the poor reflectivity of these objects.

They are so far from the Sun that solar rays are terribly weak, and many of the objects themselves are dark, which means that they reflect very little light to enable astronomers to identify and measure

them.

In Varuna's case, the asteroid was easy to spot because it shone brightly, thanks to its reflective surface.

In a commentary, US-based astronomers Stephen Tegler and William Romanishin said they were excited by the discovery of Varuna.

It could vindicate the US astronomer Clyde Tombaugh, who in 1930 found "Planet X," the

long-suspected ninth planet of the Solar System, and named it Pluto, but continued his search of Kuiper Belt in the belief that other planets were still to be discovered, they said.

"Their work raises the possibility that Pluto is not the only Planet X, but perhaps one of several," said Tegler and Romanishin.

"(...) We can now imagine that bodies even larger and more distant than Pluto will be found."

Other discoveries could come with the launch of a space-based telescope in 2002 to measure the infrared emissions of distant objects, something that is difficult to accurately achieve from the Earth

because of the filtering effect of our planet's atmosphere, they said.