There is a bogus e-mail chain letter, sometimes titled "Mars Spectacular," spreading across the Internet. It claims that on August 27th the planet Mars will dazzle the world, appearing brighter than ever in history and "as large as the full Moon to the naked eye." The problem is that "August 27th" is actually August 27, 2003. Mars did make a historically close pass by Earth at that time. The Red Planet puts on another fine show in 2005, but it will pass closest to us in October and November this year, not August. To the naked eye Mars will look like a bright star, not the full Moon.

As earth and mars orbit the Sun, they make a close approach roughly every 2 years 2 months. This time is called opposition because from Earth, Mars appears opposite the Sun in the sky. On average the two planets come within 48 million miles of each other. But because Mars's orbit is fairly elliptical, the minimum separation between the two planets varies quite a bit from one opposition to the next.

In late August 2003 Mars came within 35 million miles of Earth, but at its best in late October and early November 2005 it will come no closer than 43 million miles. By comparison, the Moon orbits the Earth at an average distance of about 240,000 miles.

To the naked eye, the Moon appears roughly 0.5 degree across. Later this year Mars will reach a maximum apparent diameter of only 20 arcseconds (compared to 25 arcseconds in 2003). That's 0.005 degree, which is way too small an angle to resolve with the naked eye. But if you observe Mars in a telescope at a magnification of 100x, the planet's angular size in the eyepiece becomes 0.5 degree. In other words, Mars in a 100x telescope will appear as large as the Moon does to the naked eye.

You don't have to wait till October or November to see Mars. Early this week it's especially easy to find. Go out a little before midnight, and look toward the east to find the rising Moon, now in its waning gibbous phase. On Tuesday night, August 23rd, Mars shines to the lower left of the Moon, as shown here. The next night, August 24th, the planet gleams closer to the Moon's lower right. And on Thursday the 25th, Mars is farther to the Moon's upper right.

There's no chance of misidentifying Mars. The planet is the brightest "star" in the sky, and its distinctive orange hue gives it away in an instant.