656 light seconds
Comet Hale-Bopp was a treat mostly for northern hemisphere observers in 1997. Its passage through the inner solar system was relatively stately, and was visible to the naked eye for well over a year. At its peak in 1997, Hale-Bopp developed two tails - the bright white dust tail, and a blue tail made from glowing ionised gas. Hale-Bopp will come by again - just not for another 2400 years or so!
Credit: Image made in visible light by Dan Schechter.
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