Two teams of researchers have proposed the existence of an unseen planet
or a failed star circling the sun at a distance of more than 2 trillion
miles, far beyond the orbits of the nine known planets. The theory,
which seeks to explain patterns in comets' paths, has been put forward
in research accepted for publication in two separate journals. ...
Speculation about the existence of unseen celestial companions dates
back far before the discovery of Pluto in 1929 ... No telescope has yet
detected this object. But on the basis of its gravitational effect, John
B. Murray, a planetary scientist at Britain's Open University,
speculates that the object could be a planet larger than Jupiter, the
biggest of the solar system's known planets. Murray puts the object's
orbit at 32,000 AU, or 2.98 trillion miles from the sun. His proposal
appears in the Oct. 11 issue of the Monthly Notices of the Royal
Astronomical Society. ...
Meanwhile, researchers at the University of Louisiana at Lafayette say
the object could be a planet or brown dwarf - that is, a dark, failed
star - roughly three times the size of Jupiter and orbiting at 25,000
AU. ... How could such a massive object exist so far from the sun? The
researchers say a planet or dark star could have coalesced during the
formation of the solar system billions of years ago, but more probably
would be a passing celestial body that was captured by the sun's subtle
gravitational pull. .... "We've all wondered whether there was something
out there," said Brian Marsden, who heads the International Astronomical
Union's Central Bureau for Astronomical Telegrams as well as the Minor
Planet Center at the Smithsonian Astrophysical Observatory.
