It stands no chance of satisfying the die-hards in the "Pluto is a planet" brigade, but the International Astronomical Union has provided a small boost to Pluto's status almost two years after it was downgraded from planet to the new class of "dwarf planet". There had been a move then to salvage some of its reputation by labelling similar dwarf planets as plutons but this term was abandoned since it clashed with an existing geological one.

Now, and although it has unfortunate echoes of a painful medical complaint, the IAU has ruled that dwarf planets beyond Neptune are to be classed officially as plutoids. To qualify as a plutoid, a body must be large enough to be pulled into a nearly-spherical shape and orbit beyond Neptune along with several neighbours. Besides Pluto itself, the only other known plutoid is Eris which is a shade larger than Pluto and orbits the Sun every 557 years, as opposed to Pluto's 258 years.

Many more icy trans-Neptunian objects (TNOs) are known, and astronomers are confident that more plutoids will be discovered among them.

The New Horizons probe, en route to reach Pluto in 2015 and perhaps a TNO or two afterwards, crossed the orbit of Saturn 10 days ago, 28 months after it was launched. Meanwhile, the Phoenix lander is making its first analyses of soil samples scooped from the Martian surface. Finally, and after several delays, the Gamma-ray Large Area Space Telescope (GLAST) made it successfully into orbit just a week ago.