To see Mars like this, you'd have to be floating in Earth orbit and peering through the Hubble Space Telescope. Hubble took this image in August 2003, when Mars made its closest approach in almost 60,000 years.
(Aug. 7) - If no one has asked you about it yet, they probably will. A bogus e-mail chain letter, sometimes titled "Mars Spectacular," has been spreading across the Internet, as it did two years ago. It claims that on Aug. 27 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 "Aug. 27" is actually Aug. 27, 2003. Mars did make a historically close pass by Earth at that time. In August 2006, though, the Red Planet is invisible, hidden behind the glare of the sun. And, of course, to the naked eye Mars will always looks like a bright star, not the full moon.
As they orbit the sun, the Earth and Mars make a close approach every 2.2 years or so. This time is called opposition, because from our perspective on Earth, Mars then appears opposite the Sun in the sky. On average the two planets come within 48 million miles of each other. But because their orbits are elliptical (oval) rather than perfectly circular, the minimum separation between the two planets varies from one opposition to the next.
In late August 2003 Mars came within 35 million miles of Earth and in late October and early November 2005 it came within 43 million miles. Mars' next opposition will come in December 2007, when it will be farther still, 55 million miles from Earth. For reference, the moon orbits the Earth at an average distance of about 240,000 miles and the average Earth–sun distance is about 93 million miles.
The small dot, or "star," at top left is Mars as it appeared over Boston's Back Bay skyline in August 2003. Mars will not be visible at all in late August 2006.
The notion that Mars can look as large as the full moon is not as crazy as it sounds. To the naked eye, the moon appears roughly 0.5 degree across, about the width of the tip of your little finger seen at arm's length. 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 look as large as the moon does to the naked eye.
In a good telescope at high magnification, you can see a fair amount of detail on Mars: darkish surface markings, occasional clouds, and the white south polar ice cap. When Mars is above the horizon, backyard stargazers the world over enjoy telescopic views of these features every clear night.
"The Mars chain letter gets revived every August," said Alan MacRobert, a senior editor of Sky & Telescope. "I see it as a good thing, not a bad thing. It's an immunization. If you make a fool of yourself by sending it to your friends and family, you'll be less likely to send them the next e-mail chain letter you get, which may not be so harmless."
PS: The first place to check for facts about any Internet rumor, hoax or urban legend is
www.snopes.com. Bookmark it.
© 2006 Reprinted with permission from Sky Publishing Corp.
