Mars in the 'hood

The red planet will be closer than it's been in 73,000 years

January 23, 2003

Yes, it's likely to be cold. Definitely dark. But you should still get up an hour before sunrise next Monday, Jan. 27, and look southeast about 20 to 30 degrees above the horizon.

A lovely gathering will take place: Center on Venus (the brightest object in the sky). Look to the left and below Venus, and you'll see sparkling Mercury. Look to the right of Venus at the dark oval of a new moon. And a rare treat for those who live in the Eastern two-thirds of the United States: Mars just to the left and so close to the silhouette of the new moon as to suggest a ladybug perched on it.

If you live on the West coast, sorry. The moon's counterclockwise orbit is much shorter than that of Mars, so that by the time the Moon appears over San Francisco, it will be in front of Mars until after sunrise.

But should you not get up, or should your view be blocked by clouds, no matter. Something special is taking place. The third and fourth rocks from the sun are moving toward the center of the galactic dance floor. Tremendous views of Mars await for many nights throughout spring and summer.

From now until Aug. 27, the two planets will draw closer - closer than they have in the last 73,000 years, "since the time when Neanderthals looked skyward," writes Joe Rao on Space.com.

How will this come about? Start with Mars' orbit. Compared with the other nine planets, only Mercury and Pluto have more eccentric orbits than Mars. To astronomers, eccentric means a greatly elongated, or elliptical, orbit resulting in a significantly measurable spread in distance when it is closest (perihelion) to the sun, from when it is farthest (aphelion) - more than 25 million miles difference.

Such orbital swinging results in Mars experiencing a large variation in the amount of sunlight striking it over the course of its year (which is 1.9 times Earth's solar year). When it is nearest the sun, 45 percent more sunlight reflects off it. The more sunlight bouncing off Mars, the more visible it is to us on Earth.

A second astronomical occurrence this summer adds to our Martian spectacular. Besides Mars being as close to the sun as it gets in a given Martian year, Earth will be in opposition to Mars simultaneously. Earth will be between Mars and the Sun. This coincidence of Mars' perihelion with the Sun and Earth's opposition to Mars on Aug. 27, is what gives us this rare visual treat.

Combine increased visibility from sunlight with the fact that the closer one gets to an object the bigger it looks, and the red planet is going to appear much larger as summer approaches.

An anthropomorphic take on this elliptical waltz around the same sun, one that has been going on for more than 4 billion years, might be two commuters sharing the same train to Manhattan. Every now and then they find themselves together in the same car, even side-by-side seats. In time, because of proximity, they come to know each other better than they know other passengers. Given more than 400 billion stars in the Milky Way, if Mars and Earth were commuters on a train, this summer they'd be sitting in each other's laps.

The chart from Space.com shows how the two planets will close on each other. It indicates in two-week intervals how far Mars will be, and how bright it will appear, from Earth.

According to the folks at Space.com, at 5:51 a.m. EDT on Aug 27 this year, Mars will be a "mere" 34,646,418 miles away, about a third of the distance of the earth to the sun. For best viewing, always start by looking south-southeast, starting from 20-40 degrees above the horizon.