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Credit & Copyright: Stefan Seip
Explanation:
Fix your camera to a tripod, lock the shutter open, and you
can easily record an image
of star trails, the graceful
concentric arcs traced by the stars as
planet Earth rotates
on its axis.
Gradually change the focus of the camera lens during the exposure,
and you could end up with a dramatic picture like this one
where the out-of-focus portion of the trail shows off
the star's color.
In this case,
the subject is one of the most famous
constellations in the night sky,
Crux,
the Southern Cross.
Gacrux
or gamma Crucis is the bright red giant star only 88
light-years distant that forms the top of the
Cross seen here
near top center.
Acrux,
the hot blue star at the bottom of the Cross is about 320
light-years distant.
Actually a binary star system, Acrux is the alpha star of the
compact Southern Cross and lies along a line pointing from
Gacrux to the South Celestial Pole,
off the lower right edge
of the picture.
Adding a separate short exposure to the end of
the step-focussed trails to better show
the positions of the
stars
themselves, astronomer Stefan Seip recorded
this remarkable image last May in the
dark night skies above Namibia.
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NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: Crux - Southern Cross - star trail
Publications with words: Crux - Southern Cross - star trail
See also: