Dwarfworld PLUTO may not have a real DOG on it - but it does have a TAIL

A plasma tail caused by the solar wind, natch

Pluto

Dwarf planet Pluto has a "tail", according to the latest information from the New Horizons probe - a plasma tail caused by the solar wind.

New Horizons carries a tool called the Solar Wind Around Pluto (SWAP) instrument that, as the craft swung behind Pluto last week, was asked to sniff around for signs of charged particles emanating from Sol.

For a short while, SWAP didn't find find them, which is itself a find because NASA now says there's “a cavity in the solar wind … between 48,000 miles (77,000 km) and 68,000 miles (109,000 km) downstream of Pluto.”

That cavity's not empty: it contains nitrogen ions that Pluto boffins say represent “a 'plasma tail' of undetermined structure and length extending behind the planet.”

Several planets have similar tails, but the likes of Venus and Mars have rather more atmosphere to lose and rather more gravity to help them hang on to their gaseous shrouds.

New Horizons gave us all a thrill last week, but it will take many months before it can send home all the data it gathered and longer still before science can make sense of it. ®


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