By the time you finish reading this sentence, you'll be 10 miles closer
to the planet Mars.

Earth is racing toward Mars at a speed of 23,000 mph, which means the
red planet is getting bigger and brighter by the minute. This will
continue through the summer until, in October, Mars will outshine
everything in the night sky except the Moon. (You're another 40 miles
closer: keep reading!)

It's only May, now, but Mars is already eye-catching. You can see it
early in the morning, rising before the sun in the eastern sky, shining
about twice as bright as a first magnitude star.

Why are we rushing toward Mars? It's simple orbital mechanics. Think of
Earth and Mars as two runners on a circular race course, with lanes
corresponding to planetary orbits. Earth, running fast on the inside
lane, circles the course in 12 months. Mars, plodding along an outside
lane, takes twice as long to go around. Every two years, approximately,
Earth catches Mars from behind and laps it.

That's where we are now, approaching Mars from behind. Relative speed:
23,000 mph.

We won't lap Mars until autumn: October 31^st^ at 0319 UT, to be exact.
At that moment of closest approach, only 69 million kilometers will
separate us from Mars, compared to an average distance of about 250
million kilometers. It's a great time to send spaceships there.

Mindful of that, NASA plans to launch the Mars Reconnaissance Orbiter on
August 10^th^, 2005. It will reach Mars in March 2006, enter orbit, and
begin a 2-year mission to map the red planet in greater detail than ever
before. The spacecraft's high-resolution cameras will be able to discern
objects, such as rocks and rovers and crashed Mars Landers, less than 1
meter across. A radar sounder will probe for underground water while
spectrometers map the distribution of surface minerals. Other
instruments will monitor the atmosphere, teaching researchers back on
Earth how to forecast martian weather. These are key elements in NASA's
plan to eventually send humans to Mars. (For details, see the Vision for
Space Exploration.)

The Mars rovers Spirit and Opportunity are already there. They arrived
in January 2004 on the heels of another Mars-Earth close encounter in
2003. (Remember, this happens every two years.) The two robots were
supposed to stop working months after they landed, worn down by wind,
stuck in sand, or exhausted by too little solar power. Credit NASA
engineering: Spirit and Opportunity are still rolling and, if they hold
true to form, they'll be "alive" to see Mars Reconnaissance Orbiter when
it gets there, a tiny point of light in the martian night sky, mapping
the red planet for explorers of the future.

Back on Earth people are going to enjoy watching Mars swell and brighten
in the months ahead. By mid-summer, amateur astronomers with backyard
telescopes will be able to spot polar ice caps and dust storms and
strange dark markings. By autumn, even the least attentive of your
neighbors will be remarking on "that bright red thing in the sky."

Mark October 31^st^ as the best day of all: Mars will rise at sunset,
hang overhead at midnight, and "blaze forth against the dark background
of space with a splendor that outshines Sirius and rivals the giant
Jupiter himself.\" That's how astronomer Percival Lowell described a
similar close encounter in the 19th century.

Can't wait? Don't. You can see Mars any clear morning. We recommend
Tuesday morning, May 31^st^. Mars and the Moon are going to have a
lovely close encounter in the dawn sky that will absolutely wake you up.
Look for them rising in the east around 4:30 AM.

More good news: you're now 2000 miles closer to the planet Mars.

10.5 kilometer/second = 23,487.8310666 mile/hour (mph)

10.5 kilometer/second = 6.5243975 mile/second