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Old 4th March 2017, 12:47 PM   #1
.AQL. Thread Starter
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Default Old World Maps\Astronomy

Just been looking at some old world maps on google. I can't figure out what the bold curved line is that goes along the equator in this map, it looks sort of like a sine wave:

http://www.worldmapsonline.com/image...0_mural_lg.jpg

ANyone know? Is it just the path of sun? (I'm terrible at geography\astronomy )
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Old 4th March 2017, 2:37 PM   #2
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Looks like the path of the moon.

http://www.universetoday.com/122263/...till-for-2015/
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Old 4th March 2017, 4:04 PM   #3
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Quote:
Originally Posted by .AQL. View Post
Just been looking at some old world maps on google. I can't figure out what the bold curved line is that goes along the equator in this map, it looks sort of like a sine wave:

http://www.worldmapsonline.com/image...0_mural_lg.jpg

ANyone know? Is it just the path of sun? (I'm terrible at geography\astronomy )
Yes, it's the path of the Sun. The clue is the inclination matches the tropic of Cancer - Capricorn.
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Old 4th March 2017, 6:29 PM   #4
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Yes, it's the path of the Sun. The clue is the inclination matches the tropic of Cancer - Capricorn.
OK thanks.

Now if that's the path of the Sun then why do we not draw a straight line down the dead centre of those two curves to form a non-arbitrary prime meridian rather than the random one we have at the moment which is further to the east closer to Africa?
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Old 4th March 2017, 9:19 PM   #5
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Now if that's the path of the Sun
That's probably what however drew the map thought it was but it's not. Over a 24 hour period the Sun is always going to be over one parallel of latitude.


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then why do we not draw a straight line down the dead centre of those two curves to form a non-arbitrary prime meridian rather than the random one we have at the moment which is further to the east closer to Africa?
Every meridian is the same, any prime is always going to be arbitrary.

Don't get confused by those Mercator projections of the Earth that may depict areas of nigh and day.

https://www.google.com.au/search?q=m...SPF-1wIfgzv3M:


The sinusoidal shape is due to the inclination of the Earth in the direction of the Sun. Six months later it reverses, it's still arbitrary.
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Old 5th March 2017, 3:06 PM   #6
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Interesting, the map depicts both Ptolemy's and Copernicus' theories about the solar system and is dated 1660. Considering it's not long after church went and condemned Galileo for his views.
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Old 5th March 2017, 4:24 PM   #7
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Update - Correction.

The mystery line is The Ecliptic.

Quote:
The ecliptic is the apparent path of the Sun on the celestial sphere, and is the basis for the ecliptic coordinate system. It also refers to the plane of this path, which is coplanar with the orbit of Earth around the Sun (and hence the apparent orbit of the Sun around Earth).[1] The path of the Sun is not normally noticeable from Earth's surface because Earth rotates, carrying the observer through the cycles of sunrise and sunset, obscuring the apparent motion of the Sun with respect to the stars.
I guess what the map maker has done is to project the celestial sphere onto the Earth?
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Old 5th March 2017, 4:56 PM   #8
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Here's a few other old ones centered around the Pacific region. Nothing related to that line. I just thought they were interesting to look at, while we're on the topic of old maps.

https://libweb5.princeton.edu/visual...cean-maps.html

---



Close! But might need just a tad refinement yet!

Watch out for the canibali.

Last edited by shredder; 5th March 2017 at 5:00 PM.
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