Ned Potter is the science correspondent for ABC's "World News with Charles Gibson." He has reported on such topics as space exploration, the human genome and climate change.
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Mars as Big as the Moon -- Not
August 29, 2009 10:29 AM
Mars as big as the Moon? I hate to clog your computer with spam, but this one is going around again, so it's worth a mention.
"The Red Pla!net is a bout to be spectacular!" says the headline of an e-mail that seems to have reached uncountable thousands of people. (I can't replicate the original typeface, but the spelling and spacing are theirs, not mine.)
"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....
"Share this with your children and grandchildren.
"NO ONE ALIVE TODAY WILL EVER SEE THIS AGAIN."
Sigh. This e-mail appears to be six years old. It's been forwarded to me repeatedly by friends, asking, "This isn't true...is it?" I could answer it, but my friend Neil deGrasse Tyson, the head of New York's Hayden Planetarium, has already done much better:
"Nearly everyone I know has received an e-mail about Mars from an anonymous source, but sent to them by friends who could not resist forwarding the message to their entire address book. The e-mail declares that at the end of this month (August), the planet Mars will be closer to Earth than it has in the past 60,000 years, thereby offering spectacular views of the Red Planet. The commentary proclaims, with liberal use of exclamation marks, that Mars will appear as bright as (or as large as) the full Moon in the night sky.
"This Martian hyperbole dates from August of [2003}, when the message was mildly factual, but vastly over-stated, leading people to believe Mars would be so bright that you might need sunglasses at night while driving. The rapid spread of this information was like some sort of brain info-virus, and led to at least one daily newspaper comic that showed Mars crashing into a home while the husband and wife were indoors, debating how close the planet will come.
"Every 26 months, or so, Earth makes a close approach to Mars, as our smaller, swifter orbit "overtakes" Mars around the Sun. Because both the orbits of Mars and Earth are mildly elliptical, some close approaches between the two planets are closer than others, but by barely perceptible amounts.
"So the proximity of Mars to Earth three years ago, while indeed closer than in the past 60,000 years, was nonetheless no more meaningful than me swimming a hundred yards out from the California coast (instead of my usual seventy yards) and then declaring to the world "I have never been this close to China before."
"True, during close approaches, Mars slowly becomes one of the brightest objects in the night sky. But how bright? Slightly brighter than Jupiter's' average brightness. And not as bright as that of Venus. Yet nobody has ever issued warning statements about the visibility of Jupiter or Venus. In any case, Mars has had a "close approach" 3,000 times in recorded history, and, of course, billions of times in Earth's history.
"Now it's time for you to send this antidote to ail the infected people in your address book."
If you're curious, you may want to play with the Jet Propulsion Lab's Solar System Simulator. It can show you just how close--or not--Mars really gets.
Right now Mars is about 150 million miles from Earth. The Moon is about 240 thousand.
August 29, 2009 | Permalink | Share | User Comments (6)
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Mars close pass real.
Turned off Dutchmans Ln. onto Cannons Ln., looked to my left.Just above the horizon a large orange ball, not red;almost twice the size of the moon.
7:00 to 7:20 P.M. / one evening Aug. 15 th. thru Aug.18 th./09.
Never keep track of the date anymore.
Just nose to the grind stone, plowing along like everyone else. looked up for a few seconds, what a sight to see.
Posted by: Wm. Paul Mahoney Jr. | Aug 30, 2009 8:50:09 AM
Paul, what you saw was the moon. I've seen it too. It's called a Harvest moon. A bright orange color to the moon and the moon being rather large, larger then it looks normally. It happens all the time. It's an optical effect of our atmosphere. I'm not sure what exactly goes on, but it is our atmosphere. I'm sure Ned could shed some light on it. If not, I'll try to post a better explaination later.
As for the email, I've recieved it at least three times this year Ned. And about the same for the past 4 years. Each time was from my grandmother. I've explained to her each time that it isn't real, I guess she just doesn't understand. The same can probably be said for the majority of the senders.
Posted by: Lawrence | Aug 31, 2009 10:04:36 AM
I'm not sure what exactly goes on, but it is our atmosphere. I'm sure Ned could shed some light on it. If not, I'll try to post a better explaination later.
Posted by: Colon Cleanse | Aug 31, 2009 12:02:31 PM
Nice article Ned, Loved the analogy of swimming 30 yds closer to China - haha.
Posted by: Phil | Sep 1, 2009 4:38:01 PM
HARVEST MOON: Speaking of bright objects in the sky, the phenomenon of the "Harvest Moon" and "Hunter's Moon" is soon to appear.
To read explanation & history:
Posted by: Nancy Mehegan | Sep 9, 2009 12:38:00 PM
You get the same magnification and reddening of the sun when it's really just past the horizon... (Sunrise - Sunset) The magnification is due to the curve of the atmosphere.
Posted by: PM | Sep 11, 2009 1:24:21 AM
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