Explanation:
Near its closest approach to planet Earth,
comet SWAN
(C/2006 M4) brightened unexpectedly
earlier this week,
becoming visible to naked-eye observers under dark night skies.
Telescopic observers also noticed
dramatic changes in the
comet's colorful
coma
and tail, seen in this view recorded on October 25th.
To make the picture, images totaling eight minutes in
exposure time were stacked
and centered on the comet as it moved relatively quickly
against the background star field.
The picture covers about 1 degree on the sky.
Northern hemisphere observers should still
find the comet
an easy binocular target in the early evening,
even though moonlight will increase the overall sky brightness
in the next few days.
Look
toward the northwestern horizon and the constellation Hercules.
