The Red Planet:
Up Close and Personal
The two faces of Mars
Two nearly opposite sides
In August 2003, Mars blazed brightly in Earth's
skies. The last time it shone this brilliantly, our planet
was in a deep freeze and our ancestors were cozying up to a
campfire to stay warm. That frosty time was during the last
Ice Age nearly 60,000 years ago. As our ancestors sat around
their campfires gazing at the night sky, they must have clearly
seen Mars glowing like a red, burning coal. Little did they
realize that the bright object was another world much colder
than their own. Our ancestors didn't know they were witnessing
an unusually close meeting between Earth and the red planet.
Back then, there was no fanfare about Mars' close brush with
Earth. No televisions, radios, newspapers, or websites announcing
its coming. No telescopes, like the orbiting Hubble Space Telescope,
snapping cool photos of it. The red planet wasn't even called
Mars until much later, when the Romans named it for their god
Mars at its closest approach is about four times brighter
than Sirius, the brightest nighttime star. The sight of Mars,
shining more brightly than all of the nighttime stars, may
have led our early ancestors to include the planet in their
Hubble's 'date' with Mars
The planet's close meeting with Earth in 2003, however, was
no surprise. For months before the planet's "big date" with
Earth, the media — from newspapers to television news
shows — broadcast its coming. People planned Mars parties
to witness what would be the closest meeting between the two
planets in their lifetimes. And when the big day arrived on
Aug. 27, the Hubble Space Telescope took advantage of the close
visit by taking detailed snapshots of the planet.
Greetings from Mars
The pair of Hubble images of Mars represents a "postcard
view" of the planet at its closest approach to Earth.
The two images, taken 11 hours apart, reveal two nearly opposite
sides of Mars.
The images, taken Aug. 26 and 27, reveal a harsh landscape
of craters, canyons, and extinct volcanoes. These features
are similar to those seen on Earth and the Moon. For example, meteoroids have
hit Mars, creating pockmarks, or craters, similar to those
on the Moon. The red planet's canyons and volcanoes are like
Earth's Grand Canyon and Kilauea volcano.
Unlike Earth, the
planet is bone dry. There are no lakes, oceans, or rivers.
Some of the planet's craters and canyons, however, may have
held water. The biggest mystery is this: Where did the water
go? Although there is no water on Mars, there is dust everywhere.
Some of the dust is fine, like powder, and red; some is larger,
like sand, and dark.
Catching up with Mars
Mars at opposition
What event brought Mars and Earth so close that the Hubble
telescope could snap these awesome pictures of the red planet?
Two factors led to the unusually close meeting.
all planets in our solar system, Earth and Mars orbit the
Sun. Earth is closer to the Sun, and therefore races along
its orbit more quickly, going around the Sun in 365 days, or
one year. Earth makes nearly two trips around the Sun in the
same amount of time that Mars takes to make one trip (687 Earth-days).
26 months, Earth catches up with Mars. When this happens, Mars
and the Sun are on opposite sides of Earth, and Mars is said
to be in "opposition." Opposition
is the best time to observe Mars because the red planet is
closer, brighter, and more fully lit than at other times.
The second factor that created this close meeting was the
distance between Earth and Mars during the 2003 opposition.
The distance at each opposition changes because neither planet’s
orbit is perfectly round. Earth’s orbit is almost, but
not quite, circle-shaped, while Mars’ path is a little
more oval-shaped. (See illustration
of Mars at opposition.)
The last five
times the planets lined up, the distance between them decreased,
ending in 2003’s unusually close
approach. That year, opposition occurred where the orbits of
the two planets were about as close as they ever get.
The next time Earth and Mars come this close — in 2287 — your
might witness the event.