Phobos: Doomed Moon of Mars
Explanation:
Mars,
the red planet named for
the Roman god of war, has two tiny moons,
Phobos and
Deimos,
whose names are derived from the Greek for Fear and Panic.
These
Martian
moons may well be captured
asteroids
originating in the main asteroid belt between Mars
and
Jupiter or perhaps from even more
distant reaches of the
Solar System.
In this 1978
Viking 1 orbiter image,
the largest moon,
Phobos, is indeed seen to be a
heavily cratered asteroid-like object.
About 17 miles across, Phobos
really
zips through the Martian sky.
Actually rising above Mars' western horizon and setting in the east,
it completes an orbit in less than 8 hours.
But Phobos is doomed.
Phobos orbits so close to Mars,
(about 3,600 miles above the surface compared to 250,000 miles for
our Moon)
that gravitational tidal forces are dragging it down.
In 100 million
years or so it will likely crash into the surface or be shattered by stress
caused by the
relentless
tidal forces, the debris forming a ring around Mars.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
