Mars won’t be as big as the Moon! Get over it!

By Phil Plait | July 27, 2007 11:55 am

Every year. Every fracking year.

The email, I hear, is going around again. The one that says that if you go outside next month and look at Mars, it’ll be as big as the Moon. You know; the one I debunked here and here and here and here, every year since this dumb thing started back in 2003.

Short and sweet: Mars won’t look big to the eye (the email says, not very clearly, that through a telescope mars will look as big as the Moon does to the eye) in August. It never gets that close. It won’t even be particularly bright in August; it’ll shine at magnitude 0.4 or so, roughly as bright as the star Aldebaren, which in fact is just a few degrees from Mars in the sky (they make a nice pair, too, since they are both ruddy in color as well).

As you can see in this image, in August Mars won’t be at its closest to Earth, and in fact will be about 180 million kilometers (over 100 million miles) away.

So don’t believe what you read in emails, OK? Happily, lots of other blogs, like Universe Today are trying to defuse this as well, so spread the word.

CATEGORIZED UNDER: Astronomy, Debunking

Comments (71)

  1. Yeah, I read that a few weeks ago, and made sure that I updated out club’s website with the correct info (like I have done for the past few years), and blogged about it on our SpaceWatch page.

    Someone has less of a life than I do, apparently.

    Plus Phil, did you see this one?

    Galaxy hoax claims we’re aliens

    It’s sad that people will believe this stuff.

  2. Michelle

    Again? I can’t believe that thing is still living.

  3. There’s a power point circulating (I can send you a copy if you want) with a hubble picture of the Ring Nebula. The power point refers to it as “God’s Eye” and goes on about making prayers/wishes etc.

    But all the wishes won’t matter when we’re crushed by a super close Mars! muahahah :)

  4. DGKnipfer

    BA,

    You should have a list of annual hoax responses that automatically post for you. The first two hoaxes in need of annual debunking that come to mind are;

    1: The Mars will be as big as the Moon hoax
    2: The balance an egg on the equinox hoax.

    I’m sure that there are others that crop up at the same time every year.

  5. OptimusShr

    Kevin: Phil debunked that claim here a while ago.

    Anyway I dugg it to help keep it from spreading, I encourage everyone else to do the same.

  6. Mike

    Phil, how do you KNOW mars wont appear that big in the sky? You yourself are a man of sceince, so you should know: NOTHING is ever 100% certian. I cant beleive you go around calling other people stupid and idiots and you dont even understand it yourself! We who beleive in the BIBLE have our own saying: look to the moat in your own eye.

    And another one: with GOD anything is possible. if He wants mars to look as big as the moon, it surely will.

    2 Kings 2:23-24

  7. MichaelS

    Your “here, here, and here” links skipped 2004 and link to 2006 twice. . .

    Now here’s my question: will it look as big as the full moon at zenith or horizon?!

  8. Frank Ch. Eigler

    That bit of pretend-not-swearing with “frakking” is getting a bit old.

  9. to Mike: I before e except after c (and in “science” I guess).

  10. Tom

    Mike: Excellent satire, my friend! I almost believed you really were a crazed bible thumper.

  11. Rowsdower

    I get this e-mail from my aunt every year (along with a comment saying that it’s false.) She sends me stuff like this all the time and I wish she’d stop doing it. Heh.

  12. I was so pissed when my brothers sent out this email a couple of years ago that I wrote back to everyone on the list with facts including actually measurements so it read like an extremely boring text book. It was great!

    They’ve never sent anything like that to me again.

  13. JC

    Mike,

    I don’t speak for Phil, but I am pretty sure he understands the orbits of the planets enough to be 99.999% certain.

    From me. Crawl back into your fundie hole, read your fairy tales,and leave the rational world to us. M’kay?

  14. Tom,

    *wink*

    JC,

    And how does Phil understand these orbits? He probably went to an anti-Christian anti-GOD school and learned false knowlege. The devil seeks to decieve no through obvious lies but through smart sounding ones! Phil THINKS he understands, but only GOD understands everything.

    So go read your fairy tale science books and athiest magazines and leave the REAL and TRUE world to GOD and his chosen people.

  15. MichaelS..

    The more important question? The size of the moon at perihelion or aphelion?

    And just who says the “size of the full moon” means from the surface of the earth? perhaps from Mars…

  16. I meant perigee and apogee. I was thinking larger, and from Mars. :)

  17. Wow Mike you’ve managed to write the dumbest thing I’ve read today, twice. Congrats.

  18. This email is the astronomy equivalent of the swallows returning to Capistrano.
    When it starts showing up in people’s inboxes, astronomers know it’s nearly August! ;)

  19. Phil, how do you KNOW mars wont appear that big in the sky? You yourself are a man of sceince, so you should know: NOTHING is ever 100% certian. I cant beleive you go around calling other people stupid and idiots and you dont even understand it yourself! We who beleive in the BIBLE have our own saying: look to the moat in your own eye.

    And another one: with GOD anything is possible. if He wants mars to look as big as the moon, it surely will.

    2 Kings 2:23-24

    Actually the bible quote involves a “mote”. A “moat” is defensive mechanism… something that surrounds a castle or other building.

    But in answer to the “how do you KNOW”… planetary motion and the optics applicable to how big something appears in the sky are both well understood. That assertion that “everything is possible with God” underlines the fact that it will not look as large as the moon because there is no evidence for the existence of God nor any evidence that, even if God did exist, he would be inclined to make Mars look huge.

  20. DrFlimmer

    Mike, do you really mean what you have written? Hard to believe for me!
    I do believe in god, but I am also pretty sure that god would not so obviously act against his own rules. Because if he has “created” the universe he also “created” the rules it follows.

    And you said: We can never be 100% sure in science. If you mean the uncertainty principle, well, this just “works” for very small scales, nanometers and that kind. On larger scales it is negligible or else you could see yourself walking around the north pole while you are sitting in front of your computer reading this.

  21. Oh bleah, mike got me. :)

  22. Mike,

    Are you serious? There are commenters here that often post tongue-in-cheek comments, so I thought I would ask. You could be sincere in your post or you could be kidding around.

    Since I know there are people in this world that would make your comment in all sincerity, I am going to go out on a limb and assume you are too. Here is my reply spelled out:

    According to the rules of science (e.g. empiricism, or observing the universe to gather knowledge), Phil doesn’t strictly KNOW by observation that Mars won’t look as big as the moon next month. The event hasn’t happened yet. But the essentially same event has happened billions of times before and in all of human history Mars has NEVER looked as big as the moon. So he is predicting with some vanishingly small amound of error that Mars will appear the same as it has billions of times before given the circumstances upon us. Since there is no new information that he knows of to modify his prediction, he is going ahead and predicting the future, given a HUGE amount of evidence for its exceedingly high probablity.

    Scientists don’t require 100% certainty before they make claims or predictions. If they did, they wouldn’t make claims or predictions about anything. Scientist try to be aware that there is error in every measurement or conclusion. In this case, the error is so small that it isn’t worth mentioning. It isn’t a factor to consider; just like you wouldn’t plan for the possiblity that throwing a baseball would make the ball turn into a parrot that flew away. It has never happened before and there is no compelling information that it is even a possibility. Why worry about every imaginable contingency? Maybe Mars will decompress and get really fluffy, making it look as big as the moon. Maybe the moon will recede very quickly and look as big as Mars. Both of these scenarios can be imagined, but in order for them to happen, there would need to be some transgression of the laws of physics or some cataclysmic event. There is no information that either will happen. So, why seriously consider it? Just because one could imagine it doesn’t mean it should interfere with one’s claims about reality.

    If you think god can just break the laws of physics at his own whim, that would make for a chaotic and unpredictable universe. Over and over and over again, that isn’t what we see. We see regularity and underlying order that lets us successfully predict events over and over again.

  23. Neil

    Mike:
    I love the parody, and I would love it all the more if I didn’t hear those sentiments spoken in sincerity so often. One question, though- did you type “moat” as part of the joke? You would have to cry an awful lot to have a moat in your eye, although I guess Tammy Faye, while alive, did show that it is possible.

  24. D’oh.

    I spent a long time writing that post before I saw the back and forth from Mike et al.

    Anyway, I leave it to stand on its own merit in case there are REAL Mike’s lurking.

  25. Response to Neil

    Neil,

    Yes, “moat” was certainly part of the joke. Almost the centerpiece, actually. I write for a profession… I’d sooner hang myself than make an actual mistake like that!

    Anyway, glad you noticed!

  26. Gary Ansorge

    Is that Mike J. again? I keep wondering what the J stands for,,,(,,,erk,,,)?

    So, for all those insistent on figuring out the universe the HARD way, by dint of exhausting brain sweat, MArs is about 35 million(at close approach) miles away from earth. Luna is about 240 thousand miles away from earth. They ain’t gonna get any closer(in human lifetimes, anyway).
    Note that I spell out the miles, for those who can’t understand all those extra zeros and commas,,,

    Bible references are for non=thinkers only. It’s easy. Just turn off the brain, sit back and let someone else do the thinking,,,usually someone who wants you to send money to god, care of the intermediary.

    Phil. Just keep the links to the debunking posts. Saves a LOT of time and you need all you can get. Keep writing,,,

    Gary 7

  27. Not MikeJ

    Gary,

    It’s “Janitch.”

  28. bswift

    I love all these double-posts when everyone realizes Mike got them. ;)

  29. aiabx

    There are crazier people than mock Mike out there. I’m not sure how one could tell by the first post alone that Mike wasn’t crazy. of course, he could still be nuts, but in a way unrelated to the pseudo-fundie crap.

  30. Heather S

    Oh, but the hoaxes are FUN! Who originated the Mars one? Really, these sorts of things get more people curious about how things work. Obviously, there will always be those who prefer to remain ignorant, but occasionally a zany hoax will start someone down the path of honest inquiry. As long as it’s not panic inducing, I say let the hoaxes come and debunk them non-snarkily. Great job Phil-keep up the good work!

  31. aibabx,

    Well, it might have jumped out at you if you’d read the bible verse…

  32. Brian T.

    Chain letters are fake? Wha…? You mean to tell me that if I don’t copy and paste dire warnings in all caps to 10 Youtube videos in 10 minutes, my mother won’t die horribly?

    That’s crazy talk.

  33. bigjohn

    aiabx — You can tell that Mike was kidding because his rant had too many words spelled and capitalized correctly, plus, he used punctuation. This was especially true in the second one. Real religious ranters don’t know about stuff like grammar, spelling, etc.. Matter of fact they don’t know much of anything except those particular verses in the bible that they happen to like.

    As for the subject at hand, remember, ignorance can be cured, but stupidity is forever.

    I have been rejected by several former friends because I explained this email and some others in terms an idiot could understand. Probably why I haven’t seen it this year

  34. (doing a quick count)… Wow, Mike, 4 on the hook! Nice work! :-)

  35. KenW

    Incidentally, if you look to the moat in your own eye, even though it is small (because only a small moat will fit entirely in your eye), it will appear bigger than either the Moon *or* Mars, because it is so much closer to you than either of the heavenly bodies. Of course, it will not appear in focus, so you may need to do some optical corrections before you can accurately compare apparent sizes.

  36. Phil, PLEASE, stop using that “Continue Reading” link. If I wanted to not read the whole post, I wouldn’t have come here in the first place.

  37. Daniel P

    Aldebaran, not Aldebaren.

  38. DenverAstro

    I have a somewhat funny story about this Mars thing. Back in ’03, we had a special Mars Night at the Chamberlain Observatory and we estimated we got about 2,000 visitors because of all the false media hype. This is about 10 times our usual attendance. There I sat at my neat little Vixen refractor cranked up to about 200x explaining over, and over, and OVER why Mars didnt look more impressive. That got So old. However, Heather has a good point, there are several people who are now loyal members of DAS (Denver Astronomical Society) specifically because of that night.
    Good thinking Heather…wanna take me out to dinner? LOL

    (just kiddin)

  39. Troy

    I haven’t got the email since ’03. So maybe it is time to stop worrying about it.

  40. chris

    PsyberDave you speak like Carl Sagan, good job

    p.s. a creationist knows (at least i hope) when there beat, they skulk, soob, and avoid anymore arguments from people that actually know what theyre talking about

  41. StevoR

    Um .. Phil

    UI ahte tosay it but Mars is asbig as the Moon -in fact its noticeably bigger ….

    … Compared in true relative size of course ! ;-)

    As seen from Earth ..? Well, forget it! Mars never appears that big even at closest as everyone has pointed out.

    Great cartoon too – doubles really well for knocking that Velikovsky rubbish .. anyone else remember him and the whole “Worlds in Collision” garbage? ;-)

    Keep up the good fight BA – &, FWIW, I agree with those saying there should just be the one link to this and the other annual hoaxes.

  42. StevoR

    Sorry – I didn’t think it was posting so tried again & well that explains the double post … My internet is so @#@#@!!!$$@#!# slow right now.

    As for the ‘frakkin’ comment I think you’ll find that’s a ‘Farscape’ reference ..

    Swearing, tempting as it often, is can cause problems for others so I try to frakken well avoidf it where I can.

    FWIW My computer gets informed of its nature as a diabolical piece of excrement & I threaten to smash itdown tothesilicon fromwhence itcame all too often ..

    The one thing I’d like to see with artificial intelligence – a computer that can understand the threats you make against it and best of all one that JUST BLEEDIN WORKS!!! ;-)

    —–
    ANgry? ANGRY! Do ISOUND ANGRY YOU MANGY MICROBIAL SLIME OFF A PARTICULAR PUTRISD PUDDLE OF YOU ……. (Fade up into indecipehrable gibberish followed by huge bang as head explodes! ;-) )

  43. StevoR

    Sorry – I didn’t think it was posting so tried again & well that explains the double post … My internet is so @#@#@!!!$$@#!# slow right now.

    As for the ‘frakkin’ comment I think you’ll find that’s a ‘Farscape’ reference ..

    Swearing, tempting as it often, is can cause problems for others so I try to frakken well avoid it where I can.

    FWIW My computer gets informed of its nature as a diabolical piece of excrement & I threaten to smash it down to the silicon from whence it came all too often ..

    The one thing I’d like to see with artificial intelligence – a computer that can understand the threats you make against it and best of all one that JUST BLEEDIN WORKS!!! ;-)

    —–
    Angry? ANGRY!?? Do I SOUND ANGRY YOU MANGY MICROBIAL SLIME OFF A PARTICULAR PUTRISD PUDDLE OF YOU ……. (Fade up into indecipehrable gibberish followed by huge bang as head explodes! ;-) )

  44. StevoR

    Oh for the love of ….!

    Sorry -again – folks. :-(

  45. pepe

    These discussions also happen in the US. Idiocy gets its highest concentration there.

  46. Yes, I just got this same email this week.
    I had to tell the person that sent it to me, that they will never seen Mars as big as the Moon in the sky. I no it hurt their feelings, but the truth often hurts.

  47. JohnK67

    I saw Mars back in August 2003. I believe that’s as close as Mars even gets to the Earth. Even then it looked like a red tinted star. About the same brightness as Venus.

  48. You know, now that I think of it, I remember being disappointed on September 7, 1956, less than a month after my 8th birthday, that I couldn’t see Mars as a naked-eye disk. So this has been going on for a /long/ time.

  49. After the first time of going out to look at the moon-sized Mars and finding just another big star-looking red thing, I got another e-mail a year later. And I am thinking to myself, “Self, I should prolly look this up cause I don’t get how this could happen every year.” So, I did, at badastronomy.com, and sure enough the scientist was right and the hoaxer was wrong.

    Sad thing was, I had to break the news to my son, cause the date of Big Mars was supposed to happen on his birthday. (We still went out and peaked up anyway. Mars is pretty cool even tho this is a hoax.)

  50. Nigel Depledge

    StevoR said:
    “As for the ‘frakkin’ comment I think you’ll find that’s a ‘Farscape’ reference .. ”

    Actually, I think the word in Farscape was “frel”, as in “We are so frelled!” or “Make this frelling thing work!”. Same principle, though.

  51. Tom

    Ugh! That time of the year again. I usually get a few emails every year in our club email account. “We want to know where the best place is to view Mars on the 27th is. Will you have a special viewing event?”
    Usually my mother will send me that email also. She should know better having a space geek astronomer for a son!

    Ok, so next time you see the ISS and shuttle flying across the sky separately, tell people that those two lights in the sky are the Mars Rovers finally coming home! Ha!

  52. Chris

    The whole ‘frakking’ thing is from Battlestar Galactica, actually. (the original and the new series)

  53. Lurchgs

    Nigel / Steve

    Nigel is correct – Frell is from Farscape *(far and away my favorite space opera)*

    Frak is from Battlestar Galactica (which, despite rave reviews and Lucy Lawless, I just can NOT get interested in. In fact, do they even use Frak in this iteration, or is that strictly from the ORIGINAL bad series?)

    Phil – I was thinking that if Mars were to appear as large as the full moon, it would, perforce, be quite close to the earth. Close enough, in fact, to cause serious gravitational effects. Since you say this is a hoax, do you think it’s safe for me to return my EarthBelts (Thank you, Johnny Hart) for a refund?

  54. I got one of these emails this morning, and I thought “Oh, no, not again”…until I got a hit on my SiteMeter for “two moons hoaks”. (Good thing I link to Deanna Hoak’s blog!) So then I thought “Yippee! Unearned hits!” And, like the stat whore that I am, I wrote up my own post reprinting (and denouncing) the e-mail, and pointing to this post, and the snopes post, and the NASA post from two years ago! If you can’t beat ‘em, at least get site traffic from ‘em!

  55. Oh, and I also suggested that people who go out and are disappointed to see that Mars isn’t as big as the full Moon should also use the eraser on the tip of a new pencil (back-to-school time, there should be a few of those around) held at arm’s length to see how big the full Moon really is!

  56. Just received said email from a friend in Michigan. Replied to her with a link to this page. Seems like a long, slow battle. The speed of bad information spreading and the slower pace of corrective good information makes it look impossible, but the world is finite and eventually everyone is going to find the truth of this. And then…. and then…. no one will EVER believe ANYTHING FOOLISH ever again!! Um, yeah.

    Luckily i don’t deal often with bad science claims, but when i do – how to quickly find a good reference, a good link, something to put in a reply? Phil, you need to create an “Emergency Bad Science Response Library” or something, with corrective resources organized by hoax/misconception. Someone tells me they read that Apollo was faked? Look under “A” on the EBSRL, and i shoot off a quick email with links to some decent websites clarifying that misconception.

    Of course, just to send http://www.badastronomy.com and tell people to enjoy browsing around, would do wonders too.

  57. Love that cartoon! Reminds me of someone way back in college who told me a dream he had one morning: some planet was close to earth, like about fifteen feet away – like the cartoon – and people could just jump to travel between the worlds. Then there was a science fiction short story about a moon of Mars in such low orbit that it went through holes in rocks on the ground. Ah memories (or memories of other people’s memories…)

  58. Blondin

    Saturn is Better,

    I remember that story. I believe it was one of Asimov’s shaggy dog stories. The punch-line was the name they gave the new “moon”.

    Deimos, Phobos and … Bottomos.

  59. CrazyAsAFox

    What a perfectly timed hoax to nab the extremely gullible! Think about it everyone…what is happening Tuesday morning? What color will the Moon be and why? What color is Mars?

  60. Miley Cyris

    My teacher told me that and she looked like a total dork nad she gave lectures on it. STOP THE HOAX NOW!!!

  61. I hope Mike the bible basher on here is joking. To say that Science is False, and God is True is just crazy.

    “So go read your fairy tale science books and athiest magazines and leave the REAL and TRUE world to GOD and his chosen people.”

    So your a chosen person. you’re special. Arrogant, but special.

  62. meow

    haahaha that was entertainig :)
    aarrg
    me a pirate :)

  63. SB

    Every bloody year I get this email circulated to me & every bloody year I hit REPLY ALL & paste a link to the Universe Today website where they explain why it cannot possibly happen…

    Does no one else CHECK the information contained in emails before they forward them onto everyone they know? Google & Snopes are my two favourites…if people would bother CHECKING before clicking they would look a LOT less stupid to their friends & acquaintances!

  64. Clara

    You guys need to stop! If Nasa says it’s true than I think it’s true!!!

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