On Aug. 27, when Mars is closer to Earth than ever in human
history, the one-way travel time of light and radio signals will be
just 3 minutes and 6 seconds. Astronomers love to measure cosmic
distances in light-years. In this case, you can think of the
distance between the two planets as being 186 light-seconds
Already Mars cannot be missed. Just look low in the east-southeast
sky on any clear, balmy evening soon after darkness falls and
you'll see a fiery yellow-orange "star" blazing brilliantly.
From now into September, Mars shines with a topaz glow that is
brighter than any other object in its region of the sky, except on
those nights when the Moon is in the general vicinity (such as on
Aug. 12 and 13, which will be a great stretch of time to see the
two travelling through the sky together).
So on Aug. 27, according to astronomer Myles Standish at NASAs Jet
Propulsion Laboratory, Mars will come within 34,646,418 miles
(55,758,006 kilometers) of Earth at 5:51 a.m. EDT, which is just
about as close as it can possibly come.
At that moment, it will then take a light beam 3 minutes and 6
seconds to cross the interplanetary gulf between Earth and
Mars.
Things won't appear much different in the nights and mornings
immediately surrounding that historic moment, so great observing
can be done without worrying about the exact moment.
Opposition comes the following day, Aug. 28. The next opposition to
bring Mars this close -- closer, actually -- will not occur until
Aug. 29, 2287. The distance will be 34,603,170 miles (55,688,405
kilometers).
Mar will appear as huge as the Moon!
for full articale pls visit http://www.space.com/spacewatch/mars_progress_030808.html
