Will Mars Really Look as Big as the Moon on August 27, 2007?

  • Context: High School 
  • Thread starter Thread starter HiggsBoson
  • Start date Start date
  • Tags Tags
    Moons
Click For Summary
SUMMARY

The discussion centers on the myth that Mars would appear as large as the Moon on August 27, 2007. Participants confirm that this claim is a hoax, originating in 2003, and supported by NASA's statements. Mars, with a radius of approximately 3,400 km, is indeed larger than the Moon, but at a distance of 34.65 million miles, it cannot appear as large as the Moon, which is 238,700 miles away. The apparent brightness of Mars is significantly less than that of the Moon, with Mars having an apparent magnitude of -3 compared to the Moon's -12.

PREREQUISITES
  • Understanding of celestial distances and sizes, specifically Mars and the Moon.
  • Knowledge of the Inverse Square Law as it applies to light and brightness.
  • Familiarity with astronomical terms such as "apparent magnitude" and "opposition."
  • Basic understanding of how light reflection works for celestial bodies.
NEXT STEPS
  • Research the Inverse Square Law and its implications in astronomy.
  • Learn about the concept of apparent magnitude and how it affects the visibility of celestial objects.
  • Investigate the frequency and significance of Mars' opposition events.
  • Explore NASA's Mars missions and their impact on our understanding of the planet.
USEFUL FOR

Astronomy enthusiasts, educators, and anyone interested in debunking astronomical myths and understanding celestial phenomena.

HiggsBoson
Messages
5
Reaction score
0
First off, forgive me if this should have gone in the “Astronomy Events” sticky.

Long time reader… but hardly ever post.
I got this email today. It actually has been going on for some time now, since 2003 I believe.

“Two moons on 27th August 2007*
*27th August; the day the Whole World is waiting for ...
Planet Mars will be the brightest in the night sky starting August.
It will look as large as the full moon to the naked eye. This will cultivate on Aug. 27 when Mars comes within 34.65 Million miles of earth.
Be sure to watch the sky on Aug. 27 12:30 am. It will look like the Earth has 2 moons.
The next time Mars may come this close is in 2287.
Share this with your friends as NO ONE ALIVE TODAY will ever see it again. “

My question is, how much truth is behind this?
I’ve been doing some googling on it and found this:

“this e-mail can be traced back to 2003... and NASA had issued a notice about it saying that its a hoax..."

But…
Mars' radius is about 3,400 km
Moon's radius is about 1,700 km
So, Mars is about twice as big as the Moon.

Brightness obeys the Inverse Square Law. So, a lamp 1 meter away from you would have 4 times the brightness if it was 2 meters away from you. Planets and Moons such as Mars & the Moon do not emit light, but they reflect light from the Sun. Which means that Mars would reflect 4 times the amount of light than the moon... right?

So, it would look brighter but not bigger than the moon correct? It says Mars will come within 34.65 Million miles, is this correct? At that distance, Mars wouldn’t look as big as the Moon, would it? As bright, maybe… but with the Moon at 238,700 Miles away I can’t see Mars look “as large as the Moon to the naked eye”

I'm a bit lost here… please school me :smile:
 
Astronomy news on Phys.org
Mars at its closest approach is neither the size nor the brightness of the Moon.

I'd also just like to point out that Mars comes rather close to the Earth very frequently. Even if this really is the closest approach in several hundred years (I'd have to go look that up, and don't think it's true), you'll have many other opportunities to see it when it is only a fraction of a percent further away.

- Warren
 
HiggsBoson said:
But…
Mars' radius is about 3,400 km
Moon's radius is about 1,700 km
So, Mars is about twice as big as the Moon.

Brightness obeys the Inverse Square Law. So, a lamp 1 meter away from you would have 4 times the brightness if it was 2 meters away from you. Planets and Moons such as Mars & the Moon do not emit light, but they reflect light from the Sun. Which means that Mars would reflect 4 times the amount of light than the moon... right?
You seem to have missed the inverse part. If the lamp were twice as far away, we would say that it is four times dimmer.

The amount of light that a planet or moon reflects depends on its cross-sectional area and its albedo, or how much light it absorbs. If the Moon and Mars had identical compositions, Mars would indeed reflect 4 times as much as the Moon.

So, it would look brighter but not bigger than the moon correct? It says Mars will come within 34.65 Million miles, is this correct? At that distance, Mars wouldn’t look as big as the Moon, would it? As bright, maybe… but with the Moon at 238,700 Miles away I can’t see Mars look “as large as the Moon to the naked eye”

I'm a bit lost here… please school me :smile:

The moon has an apparent magnitude of -12, and Mars has a max apparent magnitude of -3, which means that Mars is ~4000 times dimmer than the Moon.

IIRC, this whole hoax originated with someone mangling the awkward statement that in August 2003 Mars would appear in a telescope to be as large as the Moon to the naked eye.
 
Mars's last opposition (Aug, 2003) was one of the closest in a while, but the next one is only going to be a couple percent further away.

Btw, Mars is at opposition about every 2.5 years, which means the next opposiiton isn't August, but December 24. :rolleyes:
 
Oh. Em. Geeeee.

Is this myth doomed to repeat every two years?

It wasn't true in 2003*; it wasn't true in 2005 and it's STILL not true in 2007.


*2003 was the origin, Mars was at its closest approach - a full 25 arc seconds across - compare that to the Moon's 1800 arc seconds.

But Mars WAS the size of a full moon "WHEN SEEN THROUGH A MODERATELY-POWERED TELESCOPE"- which is how the original story was reported.
 
Well, I thought I would post a thread here during the hoax season, but I never got around to doing it. This mail has been spamming the world since the 2003 event.
 
hey guys, according to my calculations (read: celestia) Mars will be rougly 55 million miles from Earth on Dec 24, 2007. It will still be a speck, albeit a particuarly bright one.

NASA's new Mars mission is supposed to land there somewhere Spring 2008.

Cheers :)

edit for content:
July/August 2018 - Mars will be 35 million miles away. In fact, if you're in the US, July 28/27 will be the best nights to see Mars + Moon.

August 2003 - Mars was roughly 35 million away.

As for size, the arc length is orders of magnitude difference. Certainly no scenario where you'd think there were two moons.
 
Last edited:
Lunar Eclipse

Thanks for the replies concerning this hoax guys.
Mars may not be visible as big as the moon tonight, but there will be something going on in the skies early tomorrow morning. Maybe someone got confused :)


"A lovely total lunar eclipse will be visible throughout the Bay Area and all of California before dawn Tuesday morning as the Earth's shadow darkens the bright full moon, and wherever skies are clear, it will be a time to look upward wide-eyed."
-- The San Francisco Chronicle


http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/08/27/BAOFRP53L.DTL
 
  • #10
Oh boy...the Moon's going to turn red and everyone you debunked will confuse it for Mars and say "I told you so!".
 
  • #11
neutrino said:
Oh boy...the Moon's going to turn red and everyone you debunked will confuse it for Mars and say "I told you so!".

Its funny you say that because my brother just wrote me back and said... "I thought you said nothing was going to happen tonight!" lol
 
  • #12
russ_watters said:
Mars's last opposition (Aug, 2003) was one of the closest in a while, but the next one is only going to be a couple percent further away.

Btw, Mars is at opposition about every 2.5 years, which means the next opposiiton isn't August, but December 24. :rolleyes:

thank you about this information
 

Similar threads

High School The Sun's Influence on the Moon's Orbit: Is it Negligible?
  • · Replies 4 ·
Replies
4
Views
3K
High School Distance between the Earth and The Moon
  • · Replies 10 ·
Replies
10
Views
4K
Undergrad Ask an Astronomer: Mars and the Moon on August 27
  • · Replies 3 ·
Replies
3
Views
3K
Undergrad How Big of an Object Orbiting Closer to the Sun Than Earth Could Be Overlooked?
  • · Replies 17 ·
Replies
17
Views
4K
High School So what's your go-to method to locate M31 (Andromeda Galaxy)?
  • · Replies 13 ·
Replies
13
Views
3K
High School Seeing Venus with the Naked Eye - Light Pollution
  • · Replies 4 ·
Replies
4
Views
2K
High School What Are the Mysterious Zig Zagging 'Stars' in the Night Sky?
  • · Replies 5 ·
Replies
5
Views
4K
Mars Watch: Where is the Red Planet Now?
  • · Replies 18 ·
Replies
18
Views
6K
Stargazing Can distance in space be measured by human systems?
  • · Replies 22 ·
Replies
22
Views
3K
High School What Could Explain the Mysterious Beam of Plasma Seen in the Sky in 2017?
  • · Replies 8 ·
Replies
8
Views
3K