The Skeptical Teacher

Musings of a science teacher & skeptic in an age of woo.

More Martian Madness

Posted by mattusmaximus on May 6, 2009

My last entry focused on a supposed “alien” skull found on the surface of Mars, which is really nothing more than a classic case of pareidolia. Well, just today I received a bogus email from a colleague which recycles the old “Mars is going to be closer than EVER!” myth which has propagated over the last few years.


The email reads, in part…

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

The dead giveaway here is the claim that “Mars will look as large as the Moon to the naked eye.”  There is no way that Mars will ever be that close to the Earth, so long as the laws of celestial mechanics have anything to say about it.  In fact, Mars is so far away from Earth that the largest it would ever appear to us is roughly the size of the planet Venus, which is no where close to the apparent size of the Moon.

The fine folks over at have a nice, succinct way of explaining this little bit of Internet folklore…

Mars did make an extraordinarily close approach to Earth several years ago, culminating on 27 August 2003, when the red planet came within 35 million miles (or 56 million kilometers) of Earth, its nearest approach to us in almost 60,000 years. At that time, Mars appeared approximately 6 times larger and 85 times brighter in the sky than it ordinarily does. (The earlier message quoted above was often reproduced with an unfortunate line break in the middle of the third sentence of the second paragraph, leaving some readers with the mistaken impression that Mars would “look as large as the full moon to the naked eye” without realizing that the statement only applied to those viewing Mars through a telescope with 75-power magnification.)

Although Mars’ proximity to Earth in August 2003 (referred to as a perihelic opposition) was a rare occurrence, the red planet comes almost as near to us every 15 to 17 years. To the unaided observer, Mars’ appearance in August 2003 wasn’t significantly larger or brighter than it is during those much more common intervals of closeness.

Mars had another close encounter with Earth in in 2005, but that occurrence took place in October (not August), and the red planet appeared about 20% smaller than it did during similar circumstances in 2003. Mars also made a close approach to Earth in December 2007, but even then it was still about 55 million miles away from us, not nearly as close as it was in 2003 or 2005. Not until 2018 will our view of Mars be similar to the one that was available in 2003, and it won’t be until the year 2287 that Mars will come closer to Earth than it did back in 2003.<!–
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… The web site of the Students for the Exploration and Development of Space (SEDS) provides a chart displaying data about Mars Oppositions (past, present, and future), and the web site of the Hubble Heritage Project offers some nice composite telescope images from previous Mars near oppositions.

It is interesting to see how some otherwise rational & clear-thinking people will forward along the most ridiculous sounding spam email without giving it a second thought.  My colleague didn’t do this – he wisely asked me about it first – but sadly he is in the minority in exhibiting critical thinking.  Far too many people I know continue to send me these dumb spams.

With so much information, and misinformation, easily at our fingertips via the Internet, we would all do well to make a habit of critically questioning the information we see.  Most of the time this sort of spam is merely annoying, but when the lack of skepticism & critical thinking becomes habitual it can lead to some pretty scary things… more on this in my next entry.

2 Responses to “More Martian Madness”

  1. Just a quick note here…this particular article doesn’t say that Mars will look as large as the moon to the naked eye; it says that Mars will look as large at 75-power magnification as the moon looks to the naked eye.

    The article itself is still bogus…but thought I should point that out.

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