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Return of the Great Mars Hoax

— If it's August, it must be time for the Great Mars Hoax. You know, that e-mail message that says Mars is going to loom as big as the moon? It's actually a garbled version of the real science that surrounded our historic encounter with Mars in 2003. As it turns out, now is the worst time to look for Mars in the night sky. But just wait until December 2007...

Over the past couple of weeks, I've received several inquiries about claims that the Red Planet will be unusually, even uncomfortably close to Earth next weekend. From Myanmar, the country formerly known as Burma, Win Kyaw wrote:

"Mars can be seen with our naked eyes in this month of Aug? How big?  ... Is there any danger of tidal waves in the oceans on Earth?"

Win was no doubt referring to e-mail chain letters like this one, preserved in the Urban Legends Reference Pages:

"The Red Planet is about to be spectacular! This month and next, Earth is catching up with Mars in an encounter that will culminate in the closest approach between the two planets in recorded history. The next time Mars may come this close is in 2287. Due to the way Jupiter's gravity tugs on Mars and perturbs its orbit, astronomers can only be certain that Mars has not come this close to Earth in the Last 5,000 years, but it may be as long as 60,000 years before it happens again.

"The encounter will culminate on August 27th when Mars comes to within 34,649,589 miles of Earth and will be (next to the moon) the brightest object in the night sky. It will attain a magnitude of -2.9 and will appear 25.11 arc seconds wide. At a modest 75-power magnification Mars will look as large as the full moon to the naked eye. Mars will be easy to spot. At the beginning of August it 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 two planets are closest, Mars will rise at nightfall and reach its highest point in the sky at 12:30 a.m. That's pretty convenient to see something that no human being has seen in recorded history. So, mark your calendar at the beginning of August to see Mars grow progressively brighter and brighter throughout the month. Share this with your children and grandchildren. NO ONE ALIVE TODAY WILL EVER SEE THIS AGAIN"

Or maybe Win saw this e-mail, captured by the San Francisco Sidewalk Astronomers:

"Planet Mars will be the brightest in the night sky starting next August 2006. It will look as large as the full moon to the naked eye. This will culminate on Aug. 27 when Mars comes within 34.65 M miles of Earth. Be sure to watch the sky on Aug. 27 12:30 am. It will look like the Earth has 2 Moons. Don't Miss it.....The next time Mars may come this close is in 2287.

"NOTE : Share this with your friends as NO ONE ALIVE TODAY will ever see it again. ONLY LIFETIME CHANCE THIS TIME"

There's even a PowerPoint presentation on the subject, preserved (with plenty of disclaimers) on the Alachua Astronomy Club's Web site.

Such e-mail chain letters have been popping up every August for the past couple of years. If we're talking about this year, absolutely none of this information is true. Mars is actually on the far side of the sun - and even if you were somehow able to make it out amid the sun's glare, it would be just a barely visible speck.

But if we're talking about 2003, some of the information in the first message is actually pretty accurate. What's been happening is that the basic specifications for the 2003 encounter - when Mars really did come within 34.6 million miles of Earth - have been repeated and, ahem, enlarged upon.

Notice how the first message says that the telescope image of Mars would seem as large as the full moon as seen with the naked eye. That was pretty much true for 2003. But in the second message, the facts are mixed up to make it sound as if Mars and the moon would be the same size this week.

If that were the case, there would indeed be bad news on the tidal wave front. As it is, however, Mars basically has no effect on the tides, even during its closest approaches.

And it'll be a while before Mars is in a good viewing position again. This December, the Red Planet will be emerging from the glare of the sun and should be visible in the morning sky. Its next close approach is due in December 2007, but even then, it will still be 55 million miles away. Thus, the view won't be as spectacular as it was in 2003 or even 2005. In fact, the year 2018 is the next time our view of Mars from Earth will be anything like it was in 2003 - and it'll take until 2287 for Mars to come closer than it did three summers ago.

This video from MSNBC's "The Most" provides additional background from the University of Colorado's Larry Esposito, and the Alachua Astronomy Club offers this fantastic visual aid.

If you were looking forward to a monstrous Mars, don't be totally disheartened: There's still plenty to see up above. Just before dawn on Tuesday, the moon will make a joint appearance with Mercury, Venus and Saturn on the eastern horizon. Check out this map from SpaceWeather.com for a guide. And this weekend, you can track the crescent moon's close encounter with Jupiter and the bright star Spica in the evening sky.