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Space.com
updated 8/18/2003 9:36:53 AM ET 2003-08-18T13:36:53

On Aug. 27, Mars will be closer to Earth than in nearly 60,000 years. This “close approach,” as it’s being billed, has some folks worried about potential dangers here on our planet.

Space.com
ONE SPACE.COM reader asks: “Will it be dangerous when Mars gets that close to Earth? It has me a little worried.” Others have e-mailed to say they heard there would be earthquakes or other disasters. One of the many rumors going around says the two planets will collide.

The true gravity of the situation is benign. There is absolutely nothing to worry about.

At its closest, Mars will still be nearly 34.65 million miles away. The effectiveness of gravity is a function of mass and distance, so while the pull of an object is said to act across the cosmos, it does so with ever-diminishing effect. At great distances — such as between Earth and the other planets — the gravity of an object becomes little more than background noise, like the hum of a Cadillac from 20 blocks away amid the cacophony of a construction site in Midtown Manhattan.

Other readers say they heard Mars will look as big as the Moon. It will not. On Aug. 27, Mars will look pretty much like it looks now, shining as a very bright star-like point of light. With a telescope, of course, you can make it as big as your wallet allows.

WHY THE RUMORS?

Planetary doom prognostications pop up again and again because a handful of astrologers and self-anointed visionaries persist in disseminating garbage about how the positions of the planets can affect Earth by generating earthquakes, storms or other catastrophes. The Internet has made publishing of these false claims easy and more frequent.

“Only those who are foolish enough to think the motions of the planets have a bearing on their lives believe in this pseudo-science,” says Joe Rao, SPACE.com’s Night Sky columnist. He has been getting e-mail about this, too.

“There will be those who will try and convince the masses that this close approach will mean terrible cataclysms and catastrophes that will befall our planet,” Rao said. “This close approach between Mars and Earth will have no effect on any other celestial bodies in space, including the Earth itself.”

Forecasts of calamity typically precede alignments of several planets, as when three or more of the worlds inside Neptune gather approximately along a line in space so that, from Earth, we can see them bunched up in the night sky.

Groupings like this occurred in 2000 and again in 2002. Earth did not crumble.

Nothing unusual happened during other planet alignments through recorded history, either, and nothing unusual will happen on Aug. 27, except, of course, a whole lot of people around the world will step outside to look up at a cosmically historic event.

On that date, Mars will be slightly closer than ever in human history. The proximity owes to a regular occurrence of the two planets being on the same side of the Sun and the rare chance that Earth is about as far from the Sun as it ever gets just as Mars is about as close as it ever gets. (The two planets’ orbits are not quite circular). In astronomers’ parlance, Mars will be at opposition.

Mars has been almost this close during previous oppositions. In fact, the extra closeness this time is less than 1 percent compared to a similar setup in 1971.

Mars will shine brightly. It will look great in a telescope. It will not kill you.

THE NUMBERS

The gravity of Mars or any planet, given its relative small size and great distance from our own, is simply inconsequential.

The Sun and Moon do all the significant tugging around here. And these are real effects, stabilizing Earth’s rotation, creating tides in the ocean, and even causing the rock-hard crust of the planet to rise and fall daily.

The Moon, though fairly small, is responsible for about two-thirds of tides because it is just 238,900 miles from Earth, on average. The much larger Sun — even though it’s about 93 million miles away — contributes the rest. For the record, the Sun makes up more than 99.8 percent of the entire mass of the solar system.

The combined gravity of all the planets, even if lined up and all as close as possible to Earth at one moment, just doesn’t matter to Earth at all compared to the Sun and Moon, according to NASA scientists.

Still the rumors are rampant. One reader asked Joe Rao if Mars will hit Earth.

“The odds that Mars will crash into the Earth on Aug. 27 are about as good as the Detroit Tigers winning the 2003 World Series in 4 games.”

As of this writing, the Tigers were in the cellar of the American League Central Division with, by far, the worst record in baseball. And Rao is joking, of course. The Tigers have a much better chance of soaring to mythical heights than Mars has of fulfilling any of the silly mystic forecasts you might hear.

© 2003 Space.com. All rights reserved.

© 2013 Space.com. All rights reserved.

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