The Crab that Played with the Planet
Wandering
through the constellation Taurus,
Saturn
made its
closest approach to planet Earth last month, tilting its lovely rings
toward appreciative skygazers while rising high in midnight skies.
On January 4th and 5th, Saturn also crossed in front of the
high and far-off
Crab Nebula (M1), a cosmic cloud of
debris from a stellar explosion and first on the list of
astronomer Charles Messier's
celestial sights.
But Saturn
and the Crab made poor playmates,
as light from the bright planet overwhelmed the
the diffuse nebula, all but hiding the Crab
during the transit.
Taken on January 2nd,
a few days before their closest encounter,
this composite digital image illustrates the problem.
The subtle
nebula is just visible at the right,
while on the left, light from a drastically over-exposed Saturn
overflows its pixels.
Composited into the image is a correctly exposed picture of
ringed Saturn
with the Saturnian moons labeled.
The well-exposed Saturn image was also taken
on January 2nd, but captured with an exposure
lasting only a fraction of a second, in contrast with
the tens of seconds of exposure time required to
reveal the Crab.