Three big space rocks are up for promotion and I couldn't be more thrilled. A panel working under the auspices of the International Astronomical Union has come to a decision that's got to make any old science fiction fan happy.

A planet, they decreed, is any star-orbiting object so large that its own gravity pulls in its rough edges, producing a near-perfect sphere.

That definition excludes 200,000 small, odd-shaped rocks, comets and asteroids that wander around the sun.

It also means Pluto remains a planet.

But the new definition also includes three other big space rocks, including one now considered an asteroid and another long described as a moon of Pluto.

The three new planets encompassed by the group's definition would be the asteroid Ceres, Pluto's moon Charon and an object beyond Pluto called 2003 UB313, unofficially known as Xena.

Ceres owes its good fortune to the Hubble space telescpe which discovered it was spherical. I wonder if having a planet in the neighborhood will push up real estate values in the asteroid belt?

As for Charon, scientists reckon that although Pluto and Charon orbit each other, their common centre of gravity lies outside Pluto, making them a "double planet" system.

Talk about sense of wonder! A brand new distant planet, a planet in the Asteroid belt and a double planet!

Suddenly our stodgy old solar system is a vastly more exciting place. Not that the reality has changed any. Amazing what words can do.