IS THERE a tenth planet in our solar system? Astronomers who have observed Uranus and Neptune deviate from their calculated orbits, attribute such irregularities to the gravitational pull of an unknown planet, usually referred to as Planet X (Nature, Vol 363, No 6424).
But Myles Standish of the Jet Propulsion Laboratory in Pasadena claims the mass value used for Neptune in the calculations was inaccurate and this, in conjunction with some observational errors, are responsible for the difference in observed and computed values of the orbits of the two planets.
However, not all astronomers are convinced by this easy explanation. They are now searching the recently discovered Kuiper belt beyond Neptune for smaller celestial objects that might be responsible for the deviations.