The Cyber-Myth That Just Won’t Die: See Mars as Large as a Full Moon!!!

It’s hard to believe that it’s been with us for a decade now.

Ten years ago this week, the planet Mars reached made an exceptionally close pass of the planet Earth. This occurred on August 27th, 2003, when Mars was only 56 million kilometres from our fair planet and shined at magnitude -2.9.

Such an event is known as opposition.  This occurs when a planet with an orbit exterior to our own reaches a point opposite to the Sun in the sky, and rises as the Sun sets. In the case of Mars, this occurs about every 2.13 years.

But another myth arose in 2003, one that now makes its return every August, whether Mars does or not.You’ve no doubt gotten the chain mail from a well-meaning friend/relative/coworker back in the bygone days a decade ago, back before the advent social media when spam was still sorta hip. “Mars to appear as large as the Full Moon!!!” it breathlessly exclaimed. “A once in a lifetime event!!!”

Though a little over the top, the original version did at least explain (towards the end) that Mars would indeed look glorious on the night of August 27th, 2003 … through a telescope.

Mars during the historic opposition season of '03.
Mars during the historic opposition season of ’03.

But never let facts get in the way of a good internet rumor. Though Mars didn’t reach opposition again until November 7th 2005, the “Mars Hoax” email soon began to make its rounds every August.

Co-workers and friends continued to hit send. Spam folder filled up. Science news bloggers debunked, and later recycled posts on the silliness of it all.

Now, a decade later, the Mars Hoax seems to have successfully made the transition over to social media and found new life on Facebook.

Mars as seen during a close conjunction with the Moon on July 17th, 2003. Mars was 20 arc seconds in size at the time leading up to the August 2003 opposition.
How Mars really appears next to the Moon: Mars as seen during a close conjunction with the Moon on July 17th, 2003. Mars was 20 arc seconds in size at the time, leading up to the August 2003 opposition. Image courtesy of Rick Stankiewicz, used with permission.

No one knows where the Mars Hoax meme goes to weather the lean months, only to return complete with all caps and even more exclamation points each and every August. Is it the just a product of the never ending quest for the almighty SEO? Are we now destined to recycle and relive astronomical events in cyber-land annually, even if they’re imaginary?

Perhaps, if anything there’s a social psychology study somewhere in there, begging the question of why such a meme as the Mars Hoax endures… Will it attain a mythos akin to the many variations of a “Blue Moon,” decades from now, with historians debating where the cultural thread came from?

Here are the facts:

-Mars reaches opposition about every 2.13 Earth years.

-Due to its eccentric orbit, Mars can vary from about 56 million to over 101 million kilometres from the Earth during oppositions.

-Therefore, Mars can appear visually from 13.8” to 25.1” arc seconds in size.

-But that’s still tiny, as the Moon appears about 30’ across as seen from the Earth. You could ring the local horizon with about 720 Full Moons end-to-end, and place 71 “maxed out Mars’s” with room to spare across each one of them!

-And although the Full Moon looks huge, you can cover it up with a dime held at arm’s length…. Try it sometime, and amaze your email sending/Facebook sharing friends!

Important: Mars NEVER gets large enough to look like anything other than a star-like point to the naked eye.

Reality check... how Mars really appears compared to the Moon as seen during a close conjunction in 2012.
Reality check… how Mars actually appears compared to the Moon as seen during a close conjunction in 2012.

-And finally, and this is the point that should be getting placed in all caps on Facebook, to the tune of thousands of likes…  MARS ISN’T EVEN ANYWHERE NEAR OPPOSITION in August 2013!!! Mars is currently low in the dawn sky in the constellation Cancer on the other side of the Sun. Mars won’t be reaching opposition until April 8th, 2014, when it will reach magnitude -1.4 and an apparent size of 15.2” across.

Still, like zombies from the grave, this myth just won’t die. In the public’s eye, Mars now shines “As big as” (or bigger, depending on the bad hyperbole used) as Full Moon now every August. Friends and relatives hit send, (or these days, “share” or “retweet”) observatories and planetariums get queries, astronomers shake their heads, and science bloggers dust off their debunking posts for another round. Hey, at least it’s not 2012, and we don’t have to keep remembering how many “baktuns are in a piktun…”

What’s a well meaning purveyor & promoter science to do?

Feed those hungry brains a dose of reality.

There are real things, fascinating things about Mars afoot. We’re exploring the Red Planet via Mars Curiosity, an SUV-sized, nuclear powered rover equipped with a laser. The opposition coming up next year means that the once every 2+ year launch window to journey to Mars is soon opening. This time around, the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission and, just perhaps, India’s pioneering Mars Orbiter Mission may make the trip. Launching from Cape Canaveral on November 18th, MAVEN seeks to answer the questions of what the climate and characteristics of Mars were like in the past by probing its tenuous modern day atmosphere.

The circumstances for opositions of Mars from
The circumstances for the oppositions of Mars from 2001 to 2029.

And as opposition approaches in 2014, Mars will again present a fine target for small telescopes.  As a matter of fact, Mars will pass two intriguing celestial objects next month, passing in front of the Beehive cluster and — perhaps — a brightening Comet ISON. More to come on that later this week!

And it’s worth noting that after a series of bad oppositions in 2010 and 2012, oppositions in 2014 and 2016 are trending towards more favorable. In fact, the Mars opposition of July 27th, 2018 will be nearly as good as the 2003 approach, with Mars appearing 24.1” across. Not nearly as “large as a Full Moon” by a long shot, but hey, a great star party target.

Will the Mars Hoax email enjoy a resurgence on Facebook, Twitter or whatever is in vogue then? Stay tuned!

26 Replies to “The Cyber-Myth That Just Won’t Die: See Mars as Large as a Full Moon!!!”

  1. Sad comment on the state of science education. Many of us would have known this was false when we were in 4th grade.

    1. lol that stood out for me too… this is a great article nevertheless… I have a few friends that consistently blow my mind when it comes to space myths… will be sharing.

      1. Thanks for the upbeat and informative response, Dave. As to correct spelling and grammar and remembering observed events reliably, well, that just ain’t human nature. I am working out the missing letters in “Dam’d”. We need a word for a pun which arises when letters are dropped. ? p’n ?

  2. I haven’t seen this, but it’s nice to have this article handy for some pro-active measures (not that anyone will not share the hoax on my friends list, though).

  3. “A lie can travel halfway around the world while the truth is still putting on its shoes.” – Mark Twain
    Thanks to the Internet, the lie can now circle the globe several times before the truth has even found its socks.

  4. hungry brain now fed and watered……fascinating….and thank you for the information…appreciated.

  5. Ok, well, a question: how close would Mars have to be to actually appear like the full moon?

    My guess pretty damn close, though not as close as the moon, and the effects on Earth wouldn’t be much fun.

    1. Since angular diameter of the Moon is about 0.5 degrees, and the diameter of Mars is about 6,792 km, the distance from the Earth that Mars would have to be to appear the same size as the Moon, according to this Angular Size Calculator, is: 778,300 km.

  6. Bet the guys that believed that, also believe that there was a boat big enough to support 2 of every species of animal.

  7. Venus is usually the brightest planet in the night sky, but when I observed Mars in August 2003 it seemed brighter than I’ve ever seen Venus appear. Does Mars’s brightness exceed that of Venus on these rare occasions or was I just too blown away by how much brighter it was than normal in 2003?

  8. I remember one time I saw the uranus, it looked like a full moon. See what I did there ?

  9. It seems to be impossible to exterminate this kind of nonsense, just as
    the believe in horoscopes and astrology can’t be exterminated. I
    appreciate the efford ofUnderse today to counter this kind of rubbish, but
    in the end it’s impossibe to eradicate it. So let it go and keep
    imforming us about real science.

  10. Venus is larger, closer, more brightly lit and has a higher albedo. Even with the opposition heiligenschein of Mars, Venus is objectively brighter, although Venus will never shine in the middle of the night (when the sky is darkest), so that might alter your perception.

    1. Thanks for your response. So the facts of Venus’s size and higher albedo override the fact that we only see a crescent of it when it’s close to earth. Fascinating. Thanks again

    1. Some of the questions are a bit hard, especially the constellations ones. You mostly have to be interested to learn about them. But the how many planets or what the name of our Galaxy is questions seem too easy until you see the answers.

      Although unfortunately we don’t see the number of people asked in this survey.

    2. The guy explaining what a comet is should be quarantined. That level of stupidity surely must be contagious.

  11. Here’s an astronomical survey done in Belgium, which beside finding support for astronomy, finds other, less flattering facts :

    An astronomical survey conducted in Belgium

    I expect similar results in other European countries, though it would be interesting to know exactly, as far as surveys go.

    It is something to be taken into account when considering presenting astronomy to general public.

  12. The summer of my 5th grade year (I’m currently 47) my best friend told me that he heard somewhere, in August Mars was supposed to look like a landing jet.

  13. This isn’t a lie OR a hoax. Once upon a time some bubba, laying on the lounger with friend-bubba2 on the next lounger, sucking down his 9th bubba brewskie of the evening looked at the super red and super giant sun as it sets and says “Yo! With Mars so close tonite it’s gonna be looking as big as the Moon.” The comment spread, like bubba’s middle, and now even he believes it.

    The moral of this story: Science and brewskies do not mix and you cannot make a reliable telescope from beer cans.

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