This is the post I been promising for a long time.
The idea is very simple. If you know your basic astronomy, you can use both the moon and the sun to tell time and direction.
The Ecliptic is the path the sun takes in the sky. While the sun and moon does not follow the ecliptic dead on, it is still valid to say the sun and the moon rises in the East, and sets in the West.
http://en.wikipedia.org/wiki/Ecliptic
As the Moon goes through each of its phase, it revolves around the earth, which causes it to rise and set at different times. Therefore the full moon, will rise at 6PM and set at 6AM, and a new moon will rise at 6AM, and set at 6PM. However, we can not see the new moon, because the side of the moon that is getting sun is facing away from us.
This has some vocabulary, and a still frame of what I am talking about.
http://www.teachersparadise.com/ency/en/wikipedia/l/lu/lunar_phase.html
Additionally, the following site has a interactive application, which you can set the moon to different phases and see what times they rise and set.
http://www.samuelwat.com/peabody/detailedmoon/index.html
A waxing gibbous will rise at 3PM and set at 3 AM.
Notes:
Daylight light savings time has to be taken into consideration.
The moon does vary slightly in rise and set times, but it is not enough to discredit the use of the moon to get an approximation of what time it is. The following link can tell you exact time of rising setting based on your location.
http://aa.usno.navy.mil/data/docs/RS_OneYear.php
Waxing - Moon is becoming fuller, and it lighted on the right side (Think about waxing a car with your right hand)
Waning - Moon disappears, and it is dark on the right side.
I believe in the Southern Hemisphere this is all flipped, but I would have to double check on the fact. If anyone knows, let me know.
I did a previous post on using the sun as a compass for anyone interested.
http://ontologicalthinker.blogspot.com/2008/05/no-compass-no-problem.html
Sunday, July 5, 2009
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