The Planet that Won't Go Away

http://science.nasa.gov/headlines/y2...sep_goaway.htm

The Planet that Won't Go Away
NASA Science News
September 8, 2003

Mars' closest approach to Earth was on August 27th--but the red planet is
even easier to see now.

"Tony, it's still there. I can't believe how bright it is!"

That's what my mother said to me on the phone last night.
She had just stepped outside for some fresh air and was
startled by an orange star hanging over her house: Mars--so
intense it was worth a phone call.

Like millions of other people, she saw Mars for the first time
on August 27th when the red planet made its closest approach
to Earth in 60,000 years. It was dazzling, but ... "isn't Mars
supposed to be gone now?"

No, Mom. In fact, Mars is even easier to see now than it was
two weeks ago.

Consider this: Mars is receding from Earth at about 6,000 mph
(2.8 km/s). Maybe that sounds fast, but on the vast scale of
the solar system it is not. Mars was 34,647,397 miles
from Earth on August 27th. Today it is 35,532,907 miles
away--not much different.

That's why Mars remains dazzling. It's still nearby. In fact,
during the whole month of September Mars will be as close to
Earth as it's going to get for the next 15 years.

Best of all, Mars getting easier to see. Why? Because it's up
before bedtime. Like all stars and planets Mars rises about
4 minutes earlier each night. (This is a result of Earth's
orbital motion around the sun.) Back on August 27th, Mars was
barely above the horizon at sunset; you had to wait a while
for it to rise. Now, though, Mars is higher in the sky when
the sun goes down. People are noticing the red planet without
even trying.

Eventually, of course, Mars is going to fade. By late September
it will be only half as bright as it is now, and by mid-October
only 20%. The fading quickens because Mars is receding a little
faster each day. Only 6,000 mph now, the pace will increase nearly
3-fold to 16,500 mph (7.4 km/s) by the end of this month.

All these factors add up to one thing: September is a good time
to observe Mars.

Even a modest backyard telescope, a 6- to 8-inch instrument, say,
will reveal broad details on the planet's surface such as dark
volcanic terrains and the bright south polar cap. Larger 12- to
16-inch telescopes equipped with CCD cameras can record spectacular
images of individual volcanoes, wispy clouds and frosty mountains
emerging near the south pole.

Or if you're like my mom, not ready to deal with telescopes, just
use your naked eye. The planet that won't go away is a lovely
sight no matter how you look at it.