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Credit & Copyright: Tunc Tezel
Explanation:
This composite of images spaced about a week apart -
from late July 2005 (bottom right) through February 2006
(top left) - traces the
retrograde motion
of ruddy-colored Mars through planet
Earth's
night sky.
On November 7th, 2005 the Red Planet was
opposite the Sun in Earth's sky
(at opposition).
That date occurred at the center of this series with Mars near its
closest and brightest.
But Mars
didn't actually reverse the direction of its orbit
to
trace out the Z-shape.
Instead, the apparent backwards or retrograde motion with
respect to the background stars is a
reflection of the motion of the Earth itself.
Retrograde motion
can be seen
each time Earth overtakes
and laps planets orbiting farther from the Sun, the
Earth moving more rapidly through its own relatively close-in orbit.
The familiar Pleiades star cluster
lies at the upper left.
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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: Mars
Publications with words: Mars
See also: