The Pluto Comeback?

Credit: NASA/New Horizons

The beautiful mechanical orrery that hangs from the ceiling of the United Kingdom’s Jodrell Bank observatory looks old, but isn’t. Installed in 2013, the model of the Solar System carries a major clue to its relative youth: when the children who gather below are handed worksheets that ask them to name and label the system’s planets, there are eight worlds on their list. For, according to rules agreed by the International Astronomical Union (IAU) in 2006, there is no room for Pluto. (Younger readers should note: the more elderly among us were taught at school that nine planets orbited the Sun.)

Officials at the observatory near Macclesfield will, therefore, surely be alarmed at a proposal that would render their new orrery old after all. Not all scientists accepted Pluto’s demotion, and some of them have hatched a plot to put it back in its planetary place. (Not by chance, these scientists worked on the New Horizons probe that NASA sent to Pluto: a planetary explorer when it was conceived but not when it arrived in 2015.) The schoolchildren below the model should be anxious, too, for the proposal would swell the number of Solar System planets on their worksheets to more than 100 … (Nature)

Credit: NASA/New Horizons

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