Page 28 - (DK) Eyewitness - Mars

The moons of Mars

For centuries, astronomers believed Mars had moons, but no one
could find them. Anglo-Irish author Jonathan Swift accurately
described Martian moons in his 1726 masterpiece, Gulliver’s Travels,
yet no one had ever seen them. In 1877, American astronomer
Asaph Hall finally discovered the Martian moons. Hall found them
with the powerful telescope of the United States Naval Observatory
in Washington, D.C. He named them Phobos and Deimos after the
sons of the Greek god Ares—the equal of the Roman Mars. These
two tiny satellites are sometimes termed “moonlets.” They may be
asteroids, captured by Martian gravity. Hall called
Phobos’s largest crater “Stickney,” his wife’s AMAZING PREDICTION
British satirist and social critic
maiden name. Jonathan Swift (1667–1745)
described the moons of Mars in
1726—more than 150 years before
MOONLETS OF MARS astronomers found them! His
The two Martian satellites are shown here in artist’s imaginary moons orbited at distances
renderings. Phobos, the larger, is rough and cratered, and speeds that turned out to be very
with deep grooves, while Deimos appears a little similar to those of the actual moons.
smoother because its impact craters are partially buried
Deimos by the rocks and dust blanketing its surface.
Stickney Crater

Phobos
IN ORBIT AROUND MARS
This painting imagines what
Mars looks like from
Phobos, the larger of the
two Martian moons. The
view is from 100 miles
(160 km) above Phobos,
which orbit at approximately
5,800 miles (9,400 km)
above Mars.