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HOMEPAGE NEWS by Alan MacRobert
The August Mars Hoax Is Back
#checkImageURL( )
NO WAY. This is a screen shot from the version of the August Mars chain letter we received today, giant type and all. Earlier the letter mentions that the Mars view has to be magnified 75 times, but that's easy to overlook if you're skimming, and even that hasn't been true since August 2003. For the real comparison, see below.
S&T: Alan MacRobert
Actually, "hoax" is the wrong word, unless some joker out there is spreading it knowingly (quite possible). It's an e-mail chain letter claiming that Mars is about to come closer than ever in history and will look as big and bright as the full Moon with the naked eye. If your well-meaning great-aunt or your cousin's brother-in-law's dog hasn't sent it to you yet, it's probably just a matter of time.
What's going on is this. Back in 2003 (that's 2003 with a "3" on the end, folks), Mars had an especially favorable opposition, coming close enough to Earth to appear 25 arcseconds wide. By comparison, Mars is about 8" wide now (August 2007) and will grow to 16" wide around its opposition in December 2007.
Back then, someone e-mailed someone else pointing out that at a magnification of 75× in a telescope, Mars would appear as big in the eyepiece (½° wide) as the Moon does unmagnified. True enough. But two things happened, as often do with chain letters. It got rewritten bit by bit to improve the story as it got passed around, so that the "75×" was downplayed or even left out. And the chain letter kept going and going long after August 2003 was history.
Every year I tell news media, when they call Sky & Telescope, the following:
"The Mars chain letter is not a bad thing, it's a good thing! It is an immunization. If you make a fool of yourself by sending it to your friends and family, you may be embarrassed enough not to send them the next e-mail chain letter you get, which may not be so harmless."
P. S.: The first place to check for facts about any internet rumor, hoax, or urban legend is www.snopes.com. Bookmark it.
Posted by Alan MacRobert, July 25, 2007
The following comments do not necessarily reflect the opinions of Sky Publishing.
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First comments (from 15)
talking point
Posted by Stephen
July 26, 2007 At 08:47 AM PDT
When the letter arrives from someone known, it's a conversation starter. Be prepared with the next opposition, it's size and brightness, how to spot it in the sky, and offer to see it in a scope. My club has offered Mars opposition open house nights since 2003.
Put out a scope for trick or treaters on Halloween. My porch faces west, where Jupiter will be. Mars rises later, when the kids have gone to bed.
2018
Posted by Tunç Tezel
July 26, 2007 At 12:19 PM PDT
Just wait for the 2018 opposition of Mars when it will be nearly as close. Then the undead chain letter resurrecting for 15th time will have a meaning again.
And people will be able to view Mars with the total Lunar eclipse of 27th July 2018 and see their comperative sizes for themselves.
What if . . .
Posted by Terry Durbin
July 27, 2007 At 10:06 AM PDT
How close would Mars have to get to actually be the same apparent diameter as the Moon (roughly I think its about 700,000 miles) and what would the gravitational effects be on the Moon and Earth?
What if. . .
Posted by Alan MacRobert
July 27, 2007 At 11:45 AM PDT
> How close would Mars have to get to
> actually be the same apparent diameter
> as the Moon...
Interesting question. Mars is about twice the diameter of the Moon, so it would have to be about twice as far away (that is, about 480,000 miles). Gravity drops off as the square of distance, so from twice as far away a given gram of matter has 1/4 the gravitational pull. But the mass of an object scales as the cube of its diameter (assuming no change in density), so Mars has roughly 8 times the Moon's mass. Therefore, if Mars were close enough to appear the same size in the sky as the Moon does, it would have twice the pull on us.
Such a massive object coming so close to the Earth-Moon system would alter it pretty severely, depending on the circumstances of the encounter (how fast or slowly Mars passed by, and in what direction).
The most familiar effect of the Moon's gravity is the tides. Tidal effects drop off with the cube of distance, not the square. So the big Mars in the sky, twice as far away as the Moon but with 8 times the mass, would have a tidal effect equal to the Moon's.
Alan MacRobert
Mars and the moon
Posted by Justin Skywatcher
July 27, 2007 At 12:33 PM PDT
Because of my name and because I am interested in astronomy, I get about 20 of these per year. I try to explain the facts to those people. Interestingly, a few insist that I must be wrong because the email must be right! After all if it were not true, "They" would not say it, would they?
And, is that picture even Mars?
Posted by Kurt
July 27, 2007 At 12:55 PM PDT
Plus, as I recall, the image in that email isn't even of Mars, instead it's a satellite of Jupiter or Saturn. At least it's red. If I'm wrong, feel free to correct me.
Mars E-mail
Posted by Doug
July 27, 2007 At 07:43 PM PDT
Hey, my e-mail address begins with "moonwatcher" and I have
yet to recieve this 'Mars e-mail'. Lucky me!
Mars Hoax
Posted by Silvia Kowollik
July 28, 2007 At 09:53 AM PDT
The Picture shows Mars - the long dark structure is Vallis Marineris, the "Grand Cayon" of Mars...
During the 2003 and 2005 aperetition I could see this region clear throug a telescope
look to my webcam pictures captured with an 6" Newtonian:
http://www.sternwarte-zollern-alb.de/mitarbeiterseiten/kowollik/mars/mars2005/index.htm
Silvia
Picture of Mars...
Posted by Ryan
July 28, 2007 At 09:56 AM PDT
Ah yes you're right that does not appear to be mars in the picture.
Mars hoax is a pain
Posted by gary gragg
August 1, 2007 At 01:51 PM PDT
I really enjoyed looking at mars in aug. 2003, but for four years now all my friends and family send loads of e-mails to to me, as soon as they get the hoax e-mail. At first I got a lot of laughts. It was almost as funny as someone saying meade makes a great product. Now it's like everyone forgets the previous year and I send out dozens of replys with the facts. The worst part is when they say "oh I only though you would be intrested. I'm not going to get up at 3:30 am to see it anyway" ARGGGGGG!
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