Pluto has suffered a further humiliation following its 2006 ejection from the league of planets - official demotion to "second biggest dwarf planet" status.

The bad news is that Pluto is actually smaller than recently-discovered Eris, Reuters reports. More exactly, Eris is 27 per cent more massive than the former planet, according to calculations by Michael Brown and Emily Schaller of the California Institute of Technology.

The pair used data from the Hubble Space Telescope and the Keck Observatory in Hawaii to deliver this second blow to the lonely distant body. Although scientists had already determined that Eris's diameter (1,500 miles) exceeded that of Pluto (1,400 miles), they hadn't determined its mass.

Perhaps significantly, Brown "helped provoke the demotion" of Pluto, although he denied the latest findings were part of a campaign to discredit the US-discovered body. He told Reuters: "I don't think we're picking on Pluto. It's just the truth. It [Eris] just is more massive than Pluto. It's just the way it is."

Eris is appropriately named after an ancient Greek goddess of strife and discord. It's probably composed of rock and ice, as is Pluto, and follows a similar ellipical orbit round the sun.

Eris's slog around the solar system takes 560 years and carries it "anywhere from 3.5 billion miles to 10 billion miles from Earth", Brown said. Pluto does the same trip in a mere 250 years, and travels no further than five billion miles from our home planet, occasionally passing inside the orbit of Neptune. ®

Bootnote

We here at Vulture Central are starting to feel a bit sorry for Pluto, and have accordingly named it El Reg's "Most favourite non-descript orbiting object".

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