Will Mars look as big as the moon next month?

[Odinoneeye]

@Chronos

What’s funny about this e-mail is that I didn’t hear anything about this in 2004, and I didn’t encounter any of the exaggerated claims in 2003, but I’ve heard it several times from different sources this year (including the ridiculous “as large as the Moon to the naked eye” claim). What’s giving this thing legs?

I’ve seen the same thing. In 2003, I read about the claims on the Bad Astronomy website, but never heard any of them myself. Last year nothing, this year, my wife ahs gotten this Email twice.

@Mangetout

More to the point; for Mars to appear the same size as the moon, to the naked eye, something would have to have wrenched it out of its normal orbit and that something would almost certainly be A Really Bad Thing for the solar system in general.

This was my response. If Mars looked that big, either Mars or Earth had to be way out of orbit and either would be disasterous.

[wolf_meister]

It is incredible (as others have said) how this “Mars Will Be As Big As The Moon” story keeps travelling around. I’ll be disappointed if I don’t get any E-Mails about this in 2006.

You know what this reminds me of ? That Saturday Night Live sketch from about a dozen years ago - “Twenty Thousand Leagues Under The Sea”

20,000 Leagues Under The Sea - SNL Transcripts Tonight

20,000 leagues ??? Wow that’s deep !!!

And Mars will be as big as the Moon ??? Wow that’s big !!!

[RM_Mentock]

@Chronos

You’re making this harder than you need to. Tidal forces are proportional to density times angular size cubed. We’re assuming that the angular sizes are the same, and the densities of Mars and the Moon are comparable (certainly, both are denser than the Sun), so if Mars appeared as big as the Moon, then it would produce tides comparable to those of the Moon.

I was using DarrenS’s 1,000,000km figure though. Looking back, Eurograff had said “To look as big as a full moon Mars needs to get closer than 1 million km” and he just used that figure. Mars would have to be a bit closer to be the same size as the moon. I did assume they had the approx. same density, and Mars was twice the radius. Mars is actually about 10% more massive than that.

What’s funny about this e-mail is that I didn’t hear anything about this in 2004, and I didn’t encounter any of the exaggerated claims in 2003, but I’ve heard it several times from different sources this year (including the ridiculous “as large as the Moon to the naked eye” claim). What’s giving this thing legs?

People keep missing the “75x magnification” phrase, even when they read it. Even when they quote it. Check out the reaction posted on the SDMB in August 2003. MEBuckner and I were both in on that one.