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Associate

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Mars Is Coming to Us!

08/08/2006 2:52 PM

I've heard that on August 27, Mars will be closer to Earth than ever before. So will it look like it's the same size as a full moon? Mars, of course, is far greater in size than the moon, but what about the planet's gravity? Just look at what the moon does to Earth in terms of tides, for example. How will this once-in-a-lifetime near-miss affect our planet? If it moves Earth's orbit by even a degree, won't this change our seasons or yearly temperatures? Is the gravity of Mars so little that even its size won't affect us? I haven't heard anything about such changes, so I wonder what the experts say. Please rely with your thoughts.

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Guru
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#1

No Worries

08/08/2006 3:28 PM

Mars is half the diameter of Earth with about 38% of the gravitational force of Earth. Mars' closest approach to us will be a little more than 1/3 AU, or 35 million miles away. That's a little further than the grocery store! Compare that to the Moon, which is about 250,000 miles away and has about 1/6 Earth gravity. That makes Mars 140 times further than the Moon.

Since the gravity effect falls off rapidly with distance (much like the intensity of a lamp does), there will be no discernable effect as far as you will tell. As for its apparent size, you might be able to use a pair of binoculars to make out that it is disk-like, but to the naked eye (still allowed in public) it will appear more as a bright red star in the sky.

The Earth's orbit will not change, certainly not 1 degree! So don't cancel any plans you made for September.

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Guru
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#2

Mars is not coming to us!

08/08/2006 10:22 PM

Every year around this time, this story seems to surface – the one of "Mars looking the size of the full Moon". The truth is that Mars was closer to Earth then ever before in August 2003. A undated Internet post then (2003) said something like: "…with even a modest 80 times magnification, Mars will look as big as the full Moon to the naked eye". The latter part was subsequently quoted out of context… and an urban legend was born!

The 2003 'event' happened because Earth's aphelion and the Mars perihelion roughly lined up. This happens more or less every 15 years and in 2018 Mars will be in roughly similar position again. No use looking for Mars on 27 August this year!

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Active Contributor

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#3

Old news

08/08/2006 10:38 PM

This was news in August 2003. It was pretty good if you had a very powerful telescope (I saw it through the 20" refractor at Chamberlain Observatory, University of Denver).

I haven't seen any study of the effects from the close encounter but, since it's happened tens of thousands of times before, the effect must be marginal at best.

Every year, the same emails get circulated for some unknown reason... I can't imagine why anyone spends the time to resurrect this story. See http://www.snopes.com/science/mars.asp

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Guru

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#4

Mars Attacks!!!

08/08/2006 11:41 PM

I think you're absolutely right! Never in the history of the Earth has Mars come so close! It's obviously the foretold (and anxiously awaited) apocalypse!!! My only advice is to sell all your worldly possesions, empty your bank account, and send it all to me (South American address to follow). I have a spiritual in that just might save your soul. Sincerely (tongue-in-cheek), Vermin-

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#5

Insanity

08/09/2006 9:41 AM

I sure hope that you're kidding. Mars is entering apogee and cannot even be seen at night as it is ducking behind the sun. As far as Mars being as large as a full Moon and having great gravitational affect, again, I pray you are joking when you mention such insane nonsense. This has to be a joke since I don't think that even the Flat Earth Society could say stuff like this.

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#6
In reply to #1

Re:No Worries

08/09/2006 11:40 AM

Reminds me of the radio station phone call joke when the moon landings were taking place. The disk jockey claiming to be a salesman selling binoculars so one could watch the astronauts on the moon. By the way are they now called "disc jockeys"?

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Guru
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#7
In reply to #6

Re:No Worries

08/09/2006 3:30 PM

Not exactly on topic, but.....

Merriam Webster says:

Main Entry: disk
Variant(s): or disc /'disk/
Function: noun
Usage: often attributive
Etymology: Latin discus -- more at DISH
1 a : the seemingly flat figure of a celestial body b archaic : DISCUS
2 : (SNIP-Animal reference)
3 : (SNIP-Flower reference)
4 : a thin circular object: as a usually disc : a phonograph record b : a round flat plate coated with a magnetic substance on which data for a computer is stored c usually disc : OPTICAL DISK: as (1) : VIDEODISC (2) : CD

So, disk/disc, "tom(ay)to / tom(ah)to", what difference does it make?

Just call them DJ's, but usually they prefer to be called announcers, radio personalities, talen, or "hosts" of their radio shows.

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The Engineer
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#8
In reply to #5

Re:Insanity

08/09/2006 5:32 PM

For the record, we are aware that Mars appears as a red star in the night sky. Also, the world is flat and at the center of the Universe.

Best Regards,

Flat Earth Society

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Associate

Join Date: Nov 2005
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#9

Re: Mars is coming.....

08/10/2006 8:43 AM

First, apparent size: the moon appears about 30 arcminutes across, about a half a degree. Right now, Mars appears about 3 arcseconds across. It's currently near conjunction with the sun, about 2.5 AU away, and moving away at about 0.01 AU per week. In August 2003, it was at a remarkably close conjunction of about .37 AU and appeared about 25 arcseconds across. To see it, go buy a pair of arcsecond glasses.

Next, gravitational effects: consider a Mars to Earth distance of .4 AU and Earth to Sun distance of 1 AU. Mars' mass is about 6.4 x 10^^23 kg, and the Sun's mass is about 2 x 10^^30 kg. Plug these values into the gravitational force equation: F = G x (m1 x m2) / d^^2, with G = 6.7 x 10^^-11 N m^^2 / kg^^2. Compare and contrast and report back to the class. Note that the Moon has more tidal effect on the earth than the Sun, and estimate the tidal effects on the earth.

"once in a lifetime": UUMMMMM..... Oppositions occur about every 25 months, it's just that Aug 2003 was very favorable for observation. In December, 2007 - the next opposition - it will be .6 AU away, and appear 15 arcseconds across, still not bad, but you'll need your arcsecond glasses.

"gravity of Mars so little": The surface gravity isn't too bad, but it gets tired climbing all the way to the Earth. 8^)

The only effects that I've been able to tell will be happening is that a lot of people still won't take science classes, be unable to look up and use mathematical equations, and start believing every piece of email they read without question (they couldn't print it if it weren't true, right?). This ignorance will probably cause war, pestilence, famine, death & global warming. The only sure preventative is to buy a couple year's supply of Doctor Dave's GoodForNought Little Pills (TM). See me soon for them.

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