Today is the day Mars isn’t as big as the Moon!

By Phil Plait | August 26, 2007 10:58 pm

Just like every day isn’t.

I’ve already debunked this story a zillion times — every year, it seems, including 2007 — but I’ll put up a reminder now since today is(n’t) the day. The story is still around; a friend asked me the other day if there would be "two moons in the sky", and I think this is what she meant. I also did an interview for this for the Orlando Sentinel. If you see more articles on it, link to ’em in the comments! Another example: Emily.


1) Mars is not as big as the Moon in the sky.

2) Mars can never be as big as the Moon in the sky.

3) You need a decent telescope to even see Mars as a disk instead of little orangey ball of light.

4) If Mars looked as big as the Moon, we’d be in for a whole peck of trouble.

5) Mars isn’t even close to the Earth in its orbit right now. We’re approaching it, like a car on the inside track at a raceway, but it’ll be December until we’re at our closest. Even then, it’ll be tens of millions of miles away.

6) Conclusion: go outside if you want, and enjoy the night sky. Jupiter is nice. But Mars is still a long way off and not much to see.

See you next year. Sigh.


Comments (43)

  1. Thanny

    I think this whole thing started back in August of 2003, when Mars at a 60x (an easy magnification for most telecopes) was said to look as big in the eyepiece as the Moon does to the naked eye. At the time, it was true (I got some nice views a few days before closest approach).

  2. Don’t feel like the lone ranger, Phil. I’ve been getting this question from friends, co-workers and even my daughter’s friends have sent e-mail asking, “is this true?”

    I usually just point them at your site. Thanks for the current link.

    – Jack

  3. Troy

    Sorry to debunk you but if astronauts were to travel to Mars at some point in their voyage Mars would be as bit as the full moon. So never say never. Of course some might quibble about the precise definition of ‘the sky’ (Bill Clinton lawyer types who wonder what the meaning of is is.)

    …Maybe a sequel to Moonstruck called Marsstruck. Where the romance turns sour and they fight each other.

    I actually haven’t seen the email since 2003 when the viewing for Mars was actually amazingly good. I saw the pole gleaming and surface features amazingly well. So suffice to say the email is still making rounds but is not as prolific as it once was.

  4. Troy

    Oh a sequitur to my last post:

    Marsstruck theme song: When the Mars hits your eye like a big bloody sty, that’s a-war-ay.

    (Sty definition 2: a circumscribed abscess caused by bacterial infection of the glands on the edge of the eyelid;)

  5. Adam

    To be honest, I haven’t seen or heard any such rumors here in Europe but then again I prefer to surround myself with people who are capable of rational thinking. But, seriously, is this worth the time and effort? Really? If someone is stupid enough to even consider such a rumor to be within the realm of possibility are they ever going to learn? I know Mr. BA’s calling is to debunk and explain but I think this is too dumb a thing to merit any reaction. Simply below the dimwittedness level even for Mr. BA to care about. That’s what I think.


  6. Qd
  7. Wow, I’ve heard the thing about balancing an egg on the equinox and about places where a car in neutral will supposedly roll uphill but this is a completely new one to me.

    What’s the actual supposition here and how could anyone believe it?

  8. Mek

    Just an indication of how far this has spread: I live in Kuwait and every year our local astronomy club has to have an update debunking this chain mail because, apparently, someone was kind enough to translate it to Arabic many years ago. I can only imagine it spread fair and wide all across the world by now.

    I always wonder how some of the astronomers of ages past would deal with such rumors. I bet Johannes Kepler would just have a fit over this.

  9. Your photograph there clearly shows that Mars is the same size as the Moon, so I’m not convinced.

    I’m just amazed that you missed the real story, though, which is that the Martians are constructing a red cross device on their planet. Surely that’s direct astronomical evidence of Christianity? Why do you try to suppress the truth?

  10. Adam, I think it’s always worthwhile to fight to lift the veil of ignorance from those it has descended upon. Otherwise we may as well just withdraw to our ivory towers of enlightenment, and shake our heads at the poor fools who stumble about in darkness and superstition outside.

  11. Dan

    I’ve never heard of this either. But, I’ll admit, it would be pretty slick if Mars was actually as large as the moon in the night sky. That is, of course, until everything in the solar system gets all ripped to bits.

  12. “2) Mars can never be as big as the Moon in the sky.”

    And if it is, start saying your prayers.

  13. I have had visitors to my site from Australia, New Zealand, Malaysia, Saudi Arabia, Poland, Greece, and many other nations looking for information on this, so it’s not an exclusively American thing.

    Thomas, Phil did a post on this a few weeks ago, with links to previous posts on the topic that explain the history. Also try Googling “two moons on august 27”. Gratifyingly, the top results for this search are all for sites debunking the myth.

  14. If you think this is bad just wait until December! Mars overhead at midnight on Dec 24! Get ready for the Rudolph sightings to begin!

  15. Dale

    This is Awesome. I about blew Mt. Dew out my nose when I read…

    “If Mars looked as big as the Moon, we’d be in for a whole peck of trouble. ”

    Funny.. but incredibly true. Why wouldn’t people know these things. What’s happened to people’s common sense. Sheeeeeesh.

  16. Tom epps

    Phil, I volunteer at a small planetarium/observatory here in Va., and over the past three weeks I’ve been asked many times about Mars’ moon-sized apparition. Contrary to some of your respondee’s (see above) assertions, these are NOT wackos or even fringies; they are people who have recieved bad data and are curious about it.

    Whatever you do, BA, please don’t “get over it”. Keep up the good work!

    Tom E.

    P.S. The SECOND most common question we get is about “star naming” scams…and THERE is a true dilemma; do you tell the little old lady who named a 13th Mag star in Capricornus after her late husband the cold, hard truth (thereby breaking her heart); do you sidestep the issue (“I’m sorry–that star isn’t visible right now”); or do you point the telescope at a star in the general region of the coordinates she was given and thereby give her consolation whilst playing-along with
    the *&?!## @ who have decieved her?

  17. LinuxRules

    OK, I’m a rational thinker, but it troubles me the fact that I got this
    Email twice this month … so I wonder, is this going to be a “Blue Mars”?
    .. Just kidding :o)

  18. KaiYeves

    I hear you, Harold. If we did that, WE’D be the fools. Stupid 5 in the morning eclipse! I tried waking up early for the meteor shower, too, but my alarm clock didn’t go off. I’m going to learn how to use that darn thing today so I don’t miss it. And also on the subject of Mars, here’s a verse from a song I wrote (Sing to the tune of “I don’t know but I’ve been told”):
    Pareidolia (Efila Teg)
    You know it’s not your cousin Bob
    Hiding there in that ink blob
    Listen to me here today
    Some creeps wanna take your money away
    And these kinds of things they’l use
    Know this song and you won’t loose
    Pareidolia, efila teg!
    My friend, remember this:
    It may look like it but that’s not what it is!

    There’s no chopper carved in Tut’s tomb
    And their careers, these poor nuts doomed
    ‘Cause they couldn’t see the truth-
    It’s Pare I., it is not proof!
    And if on Mars you see a face
    It’s Pare I., not an alien race
    These creeps are broke, it’s not much fun
    And songs backwards they run
    Hoping messages to hear
    Listen, nutsos, loud and clear:
    (Repeat Chorus)
    Don’t be a fool and don’t fade
    To red-eye talk shows, Z-grade
    If you meet some guy who’s wrong
    Remember me and sing this song
    From ignorance they will be saved
    You’ll be a hero, you’ll be brave!
    Pareidolia, Efila Teg!

  19. Richard B. Drumm

    My 90 year old mother sends me these emails each year because her aging friends have sent them to her. So I send around my rebuttal and links to the page each year, cc-ing all the email addresses on the original email. I keep hammering away at them to check snopes first whenever they hear something amazing but it just doesn’t seem to sink in very far.

    I also have a good friend who claimed he believed the moon hoax, so I sent him the BA hoax page link and held my tongue. I haven’t had the heart to ask him if he’d read the page yet, but I’m sure he’ll express his cynicism about the government and I can ask him if he still believes in the hoax.

    Keep fighting the good fight, don’t let up for a moment!

  20. Well ,
    People wait for surprise , something difference ! Thus they easily believe ( or need to believe ) such hoax .
    Our Jordanian Astronomical Society JAS and it’s forum made its best to make it clear that it is just a hoax . Actually , Mars needs to be 111 times closer to Earth in order to be seen as the Moon .

  21. bjswift

    I’m doing my part, too, to help stomp this one out.

    Qd: no, we can’t get over it.

  22. Quiet_Desperation

    It’s Planet X!!!!!!!

  23. As the only person in my circle of friends an associates who has any education in this sort of thing, I, too, am a recipient of dozens of copies of the Giant Mars message every year, and every year I send out dozens of rebuttals (with links to the BA page).

    Last year, I made a form-letter that I could cut and paste into the reply.

    The year before that I actually invited people over one night to show them.

    But like a vampire hunter without a rosewood stake, nothing I do seems to put this hoax to rest.

  24. Quiet_Desperation

    Thinking-Outside-The-Box solution:

    “Why, yes, it *IS* true! Stand around outside in the cold and damp for hours tonight until you spot Mars!”

    You should notice a distinct decrease in the email/questions next time.

  25. Fizzle

    I was watching the local news a few days ago and they did a segment debunking this. Now if only every news station in the country did this our problems would be solved.

  26. Jewel

    One of my coworkers sent out an email to everyone last week talking about this “amazing” event. I sent him (and everyone else on the list) a link to your debunking of it. It does amaze me that people actually believe this sort of thing when just a little bit of actual thought (and/or a cursory web search) would point out the very obvious flaws in the argument.

  27. bill

    When I heard this, I was a bit skeptical, but after thinking about it, one could imagine that if Mars is very close to earth, and rises slightly after the moon, as it rises, the lensing effect of the atmosphere could make Mars look relatively large creating the impression of two moons. Ok, now that I know it is not true, I don’t feel so clever, but I am a biologist after all. I guess I should have asked my U of C cosmotologist friend as soon as I heard about it.

  28. I hear you. I have been getting all sorts of questions about this, too. In fact, I decided to just add a bit on the whole Mars/Moon hoax thing to my first lecture of the semester. Also, I wrote a posting about this at my web site, too.

  29. Hey, I just realized…go out after sunset tonight and you can see the “regular” Moon. Go at out mid-eclipse, and you’ll see the “red” Moon – IT MUST BE MARS!

    I think we’re gonna have to deal with some of that come tomorrow morning.

    I used to get 70 – 100 visitors to my blog each day. In the past few weeks I’ve been getting 200-300 visitors courtesy of the “two moons” dealie. With six hours to go in this day, I’ve had 1,044 visitors. I hope some of them are noticing the bit about the eclipse I included in large type at the end.

  30. Tim G

    Oscar Mayer wants its baloney back.

    This has penetrated the media a bit too far. Some meteorologist on the Weather Channel said that we’d essentially have two moons in the sky with mars so close. I cannot remember which meteorologist it was but it wasn’t one of the pregnant ones whose belly covers three states.

    On a radio show in Bangor, Maine (I’ve been on vacation) both hosts talked about the supposed event as fact. One caller said that her eleven-year old daughter is interested in astronomy and was very excited about mars appearing as big as the moon and, thinking the event was to happen before sunrise today, woke herself up just after midnight to see it. The mother said her daughter was “bummed”. A caller chimed in and said it was all B.S.. Hopefully, this will prevent the girl from loosing more sleep.

    I guess people have trouble conceptualizing astronomical distances.

  31. Bud S.

    Gee, it didn’t materialize? I believe the only explanation possible is that the ID’er prevented it from happening in order to protect us, being compassionate and all.

  32. Kate Z.

    I’m an astronomy educator at a science center, but it’s my husband, an amateur astronomer, who gets the “Mars as big as the Moon”
    emails forwarded to him from his mother every year. He gets irritated
    with it every year. So last year he decided to retaliate (sigh) and
    wrote up this response. In its original form, it had a wide-angle
    picture of the Milky Way and lots of different colors and fonts and so
    on, but I removed them so it could post better. You’re welcome to send this one around next year if you’d like.

    You guys: I checked out the facts on this one – it’s ALL TRUE!!!!!!!!

    On August 23, 2006 the Earth will be flying directly through the DISK
    of a GIGANTIC GALAXY. This will be an event of unprecedented
    magnitude!!!!!!!!!!!!!!!!!!!!!!! The galaxy we will be flying through
    is 10,000 light years thick and 100,000 light years wide. That’s big
    enough to take a flock of geese 3 TRILLION YEARS to fly around!!!! To the naked eye, the galaxy will appear to be ALL AROUND US. Yes, just imagine being able to look out from your house on August 23rd and see a GIGANTIC GALAXY stretching from one horizon to another. Luckily, we will not pass directly through the center of the galaxy, as this would mean CERTAIN DEATH BY BEING SUCKED INTO A SUPERMASSIVE BLACK HOLE!!!!!!!!!!!!! But, we’ll be able to see the center bulge of the galaxy as a gigantic mass of millions of stars and billowing dust clouds near the Sagittarius region of the sky.

    (insert a picture of the Milky Way here)

    (picture caption:) High-tech simulation of what this galaxy will look
    like to the NAKED EYE from your own backyard!!!!!

    THE EARTH WILL NOT ORBIT THROUGH THIS PART OF THE GALAXY AGAIN FOR ANOTHER 200 MILLION YEARS!!!!!! That’s 7.6 billion years in MOUSE YEARS!!!!!!!! So get your children and grandchildren out into your backyards on August 23 for a view of this galaxy that their children and grandchildren and their grandchildren’s grandchildren won’t see again for another 6×106 generations!!!!!

    Please pass this on to as many people as possible, or else the earth
    may really get sucked into a black hole, and it’ll be your fault for
    not forwarding the message. Note: because of light pollution in urban
    areas, the galaxy may be difficult to view. If we can get EVERYBODY
    to turn off all lights on August 23, the galaxy viewing will be an
    event of ENORMOUS proportions!!!!

    One thing to note, though: he got the Mars/Moon forwarded to him from his mother AGAIN this year. (Bigger sigh.)


  33. Moose

    Gak. Yeah, it’s definitely that time of the year again. Someone brought it up at my Mom’s birthday party a few days ago. Dad was pretty sure it was bogus in that he’d seen the same email last year, but lately he’s started to check internet rumors (and especially astronomy rumors) with me these days before “signing on”. (Yay! Progress!)

    Turns out I debunked it largely using the same points (not quite verbatim, but about as concisely) that the BA used in this blog entry. Of course, by now I’ve read enough of his debunkings to know the script.

  34. Heh… Harold, you beat me to it. I realized this morning that the blurry photos I took of the moon during last night’s eclipse do make it look a lot like Mars, and decided I had to post a comment here!

  35. Colin

    This one just went around South Africa (for the first as far as I’m aware) – I’ve gotten very tired of telling people the facts. It was apparently on the local news, which in this country is par for the course, although I never actually saw the segment myself so I can’t vouch for that. My niece (who’s 8) was the first person to bring this to my attention – it was told to her by a neighbour. How do you tell an 8-year-old they’re wrong?

  36. Brian

    Thanks for debunking this, everyone! :)

    Be careful about your language, however. Strictly speaking, Phil’s first two statements are false. Mars is, in fact, much bigger than the Moon every hour of every day… it just doesn’t LOOK as big when we see it from the surface of the Earth. And neither of them are “in the sky” either – they’re in space, or rather the inner solar system.

    Nitpicks for sure… but if people can be confused by the whole silly notion of Mars looking as big as the Earth, they can also be confused by a misplaced word or two.

  37. Brian

    Ooops – er – as big as the “Moon” (not Earth)… see, I can get my words wrong too. :)

  38. I thought the mars/ moon thing was intended to fool people who saw the (red) lunar eclipse without knowing whta was going on…


Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!


See More

Collapse bottom bar