Area on earth that moon can be seen

[beecher]

How large an area on earth can the moon be seen at one time? If I am in East Texas, how far around the earth can someone else be and still see the moon when I do?

 

[beecher]

Thank you, shuttle guy! I write a newspaper column where I answer weird questions from readers. I will use your answer. Thanks very much.

 

[Saiph]

yeah, half the world can see the moon at any one time. Generally speaking, people 1/4th the way around the world in west and east can see it.<br /><br />But it's not actually that simple, as the moon doesn't orbit the earth's equator. So that can shift which half the world see's the moon so that middle of the hemisphere that see's the moon, is shifted north or south of the equator. So sometimes, someone at the north pole won't see the moon rise for a few days, or won't see it set.<br /><br />Now, if you want to throw out a wierd idea to the readers, ask them how the moon appears in the southern hemisphere...it's upside down. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

 

[eosophobiac]

How is it 'upside down'? This sounds interesting, and if you have links about this, I'd be interested.... Thanks.<br /><br /> <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>

 

[rogerinnh]

Post deleted by RogerInNH

 

[Saiph]

<img src="/images/icons/smile.gif" /><br /><br />I know it's a "relative" thing, but it's a difference in appearance people notice. And what you described is an east/west flip, and most people don't have too much of a problem with that (as we easily deal with mirrors all the time).<br /><br />But the southern hemisphere see's the moon inverted along the north/south direction, and that has a bit more of an impact than you'd likely guess. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

 

[CalliArcale]

The reason the moon appears upside down from the southern hemisphere is because your brain perceives the "bottom" as whichever part is closest to the horizon. If you're in Alaska, the Moon appears closest to the southern hemisphere. If you're in Chile, the Moon appears closest to the northern hemisphere. If you're in the tropics, of course, it may appear leaning towards either the north or the south. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[unclefred]

The area on Earth that the Moon can see has nothing to do with the sun. It has nothing to do with when the moon rises or sets. It has nothing to do with which part of the Earth is facing away from the sun and thus dark. It does not have anything to do with how the Moon's orbit inclined to the equator. As an approximation only will 1/2 of the world see the moon at any given time. <br /><br />For an orbiting satellite, especially in the communication satellite business, what you are looking for is know as the instantaneous access area (IAA). Do an internet search and you will several papers and discussion of IAA. Since the moon is just another satellite the equations will work perfectly. The equation is Area = K(1-R/(R+H)) where K=2.556e8 km2, R= earth radius=6,378 km, H= satellite height above the earth. For the Moon's center the value of H is 384,400 km on average but depends where it is in its orbit. Thus the area on earth that can see the Moon at any give instant is 251,428,279 km2. This is about 49.2% of the Earth's surface.<br />