Saturday August 16, 2003

Close Encounters

Look for it in the night sky - an increasingly brighter, reddish "star" near the moon. That's not a star; it's the planet Mars.

Earth and Mars are rapidly converging. On August 27, 2003--the date of closest approach--the two worlds will be 56 million km apart. That's a long way by Earth standards, but only a short distance on the scale of the solar system.

Between now and August, Mars will brighten until it "blazes forth against the dark background of space with a splendor that outshines Sirius and rivals the giant Jupiter himself." Astronomer Percival Lowell, who famously mapped the canals of Mars, wrote those words to describe the planet during a similar close encounter in the 19th century.

[c.f. Approaching Mars, Science@NASA]

At the beginning of August Mars will rise in the east at 10 p.m. and reach its azimuth at about 3 a.m. By the end of August when the Earth and Mars are closest, Mars will rise at nightfall and reach its highest point in the sky at 12:30 a.m.

Astronomers call these close encounters "perihelic oppositions." Perihelic means Mars is near perihelion--its closest approach to the sun. (The orbit of Mars, like that of all planets, is an ellipse, so the distance between the sun and Mars varies.) Opposition means that the sun, Earth and Mars are in a straight line with Earth in the middle. Mars and the sun are on opposite sides of the sky. When Mars is at opposition and at perihelion--at the same time--it is very close to Earth.
I saw it for the first time last night. Mars and the moon were the only thing we could see, given the cloud cover. It was definitely bright and sort of orangeish and bright.. Tres cool.

Close Encounters ( in category SciTech ) - posted at Sat, 16 Aug, 12:10 Pacific | «e»