Mercury,
July/August 2003 Table of Contents
by
Daniel P. Joyce and Daniel M. Troiani
In
late August, Mars will come as close to Earth as it ever gets. Even
modest telescopes will reveal a fascinating wealth of detail.
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Courtesy
of Daniel M. Troiani |
With
a diameter only 53% that of Earth's, Mars is a small planet. Because
of its small size, experienced observers can discern impressive
detail on Mars only when it comes close to Earth. On August 27 of
this year, Mars will come closer to Earth than it has at any time
in the past 59,540 years. Now that it is as close as it ever gets,
even inexperienced observers using small telescopes will be able
to see intricate details.
These
details include features that make Mars more Earth-like than any
other body in the solar system in virtually every category except
for size and mass. Mars has changing weather patterns, with haze,
water ice clouds, and ground fog. It has dark markings that change
in size and color. It has polar caps. You can even see changing
seasonal effects that result from its 25° axial tilt.
On
the down side, Mars also experiences dust storms. Fortunately, these
storms are usually just local events. But occasionally they can
grow large enough to envelop the entire planet. Global dust storms
are rare enough that it is unlikely one will occur during this year’s
apparition. But during Mars’s last close approach in June
2001, several regional dust storms converged to form a single giant
dust storm that covered the entire surface except for the polar
regions.
With
its many changing phenomena, Mars will appear different almost every
time an observer looks through a telescope. This is a once-in-a-lifetime
opportunity, so try to observe Mars as often as possible this summer.
Sure enough, the one night you decide to stay indoors and watch
TV will be the night a major event will happen on Mars.
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