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Earth
and Mars are converging for a close encounter--but not as
close as some people think.
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July 7, 2005: Just when you thought it was safe to
read your email....
There's
a rumor about Mars going around the internet. Here are some
snippets from a widely-circulated email message:
 "The
Red Planet is about to be spectacular."
"Earth
is catching up with Mars [for] the closest approach between
the two planets in recorded history."
"On
August 27th … Mars will look as large as the full moon."
And
finally, "NO ONE ALIVE TODAY WILL EVER SEE THIS AGAIN."
Only
the first sentence is true. The Red Planet is about
to be spectacular. The rest is a hoax.
Here
are the facts: Earth and Mars are converging for a close encounter
this year on October 30th at 0319 Universal Time. Distance:
69 million kilometers. To the unaided eye, Mars will look
like a bright red star, a pinprick of light, certainly not
as wide as the full Moon.
Disappointed?
Don't be. If Mars did come close enough to rival the Moon,
its gravity would alter Earth's orbit and raise terrible tides.
Sixty-nine
million km is good. At that distance, Mars shines brighter
than anything else in the sky except the Sun, the Moon and
Venus. The visual magnitude of Mars on Oct. 30, 2005, will
be -2.3. Even inattentive sky watchers will notice it, rising
at sundown and soaring overhead at midnight.
You
might remember another encounter with Mars, about two years
ago, on August 27, 2003. That was the closest in recorded
history, by a whisker, and millions of people watched as the
distance between Mars and Earth shrunk to 56 million km. This
October's encounter, at 69 million km, is similar. To casual
observers, Mars will seem about as bright and beautiful in
2005 as it was in 2003.
Although
closest approach is still months away, Mars is already conspicuous
in the early morning. Before the sun comes up, it's the brightest
object in the eastern sky, really eye-catching. If you have
a telescope, even a small one, point it at Mars. You can see
the bright icy South Polar Cap and strange dark markings on
the planet's surface.
Above:
Painted green by a flashlight, astronomer Dennis Mammana of
California points out Mars to onlookers on Aug. 26, 2003,
the last time Mars was so close to Earth. Photo credit: Thad
V'Soske.
One
day people will walk among those dark markings, exploring
and prospecting, possibly mining ice from the polar caps to
supply their settlements. It's a key goal of NASA's Vision
for Space Exploration: to return to the Moon, to visit Mars
and to go beyond.
Every
day the view improves. Mars is coming--and that's no hoax.
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Author: Dr. Tony
Phillips | Production Editor:
Dr. Tony Phillips | Credit: Science@NASA
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