Longest known comet tail stretched for over a billion kilometres

By Jonathan O’Callaghan

PEKKA PARVIAINEN/SCIENCE PHOTO LIBRARY

Data from NASA’s Cassini spacecraft has revealed a record-breaking comet, with a tail that stretched more than seven times the distance between Earth and the sun.

Geraint Jones at University College London and his colleagues looked through past data from the mission in 2002, when Cassini was on its way from Jupiter to Saturn. The spacecraft had been using its plasma instrument from 2001 to 2003 to study charged particles from the sun called the solar wind.

They found a notable increase in protons detected by the …