Mars Moves in for Some Quality Visual Time

http://www.jpl.nasa.gov/solar_system...opposition.cfm

Mars Moves in for Some Quality Visual Time
Lisa Townsend
Jet Propulsion Laboratory, Pasadena, Calif.
July 28, 2003

Living too close to a neighbor may not be very appealing, but when
Earth's neighboring red planet moves closer than it's been in 50,000
years, observers expect nothing but acclaim.

This August, scientists and amateur astronomers will benefit from the
spectacular view of Mars as it appears bigger and brighter than ever
before, revealing its reflective south polar cap and whirling dust
clouds.

On August 27, 2003, the fourth rock from the sun will be less than
55.76 million kilometers (34.65 million miles) away from the Earth.
In comparison to the space between your house and your neighbor's
yard, that may seem like a large distance, but Mars was about five
times that distance from Earth only six months ago.

"Think of Earth and Mars as two race cars going around a track," said
Dr. Myles Standish, an astronomer from NASA's Jet Propulsion
Laboratory, Pasadena, Calif. "Earth is on a race track that is inside
the track that Mars goes around, and neither track is perfectly
circular. There is one place where the two race tracks are closest
together. When Earth and Mars are at that place simultaneously, it is
an unusually close approach, referred to as a 'perihelic opposition'."

Opposition is a term used when Earth and another planet are lined up
in the same direction from the Sun. The term perihelic comes from
perihelion, the point of orbit in which a celestial body is closest to
the Sun. This August, Mars will reach its perihelion and be in line
with Earth and the Sun at the same time.

The average opposition occurs about every two years, when Earth laps
Mars on its orbit around the Sun. In 1995, the opposition brought
Mars 101.1 million kilometers (62.8 million miles) from the Earth,
twice as far as this most recent approach.

"It gets more complicated as the race tracks are changing shape and
size and are rotating, changing their orientation," Standish explains.
"So this place where the two tracks are closest together constantly
changes, changing the opposition closeness as well. This is why a
'great' approach, like the one this month, hasn't happened in 50,000
years. But with the tracks closer together now, there will be even
closer approaches in the relatively near future."

Aside from visiting a local observatory, peering through a telescope
is the best way to take advantage of this unique opportunity. Since
June, Mars has been noticeably bright in the night's sky, only
outshined by Venus and the Moon. Observers in the Northern Hemisphere
will see it glowing remarkably in the southern sky in the
constellation Aquarius, best seen just before dawn.

"You're not going to go outside and see some big red ball in the sky.
It will look like a bright red star," said Standish.

The word 'planet' is derived from the Greek expression for 'wanderer.'
At such a close distance, Mars remains true to this expectation as it
consistently wanders across the night's sky. Tracking the "red
star's" movement from week to week is yet another way to appreciate
the opposition as Mars appears to dart across the sky in comparison to
more distant planets, such as Jupiter.

Although Mars will be closest on August 27, astronomers suggest
viewing the planet earlier, as dust storm season is just beginning on
the red planet and can obstruct a more detailed view.

Whether you are viewing through a telescope, glancing through a pair
of binoculars, or star-gazing outside the city, be sure to take
advantage of this once-in-a-lifetime opportunity, for Mars will not
make another neighborly visit this close until 2287.