Posted By: kland
The vernal equinox and the new moon. - 08/06/13 12:53 AM
While I have a fairly good working knowledge of the issues of linear time on a round earth, I may be having a mental block with the relationships of the vernal equinox and the new moon to the earth.
The Jewish calendar begins on the new moon after the vernal equinox. Whether you go by the real new moon or the sighting of the new moon, it shouldn't make much difference to the relationship.
The equinox can be defined when the sun is in the same plane as the earth's equator. This would occur at a precise theoretical point. I've also seen it defined when the amount of daylight equals the amount of night.
Is it possible for people in Jerusalem during Bible times to know when the sun is at the plane of the equator, that the day and night portions are the same at the equator, of which would be different in Jerusalem?
Or is it when the day and night lengths are equal in Jerusalem? I read that given an east-west line, such as a road, when the sun sets dead centered on it, that is when the day and night are equal.
Does this happen everywhere at the same time? If a day is 24 hours, then when the daylength is 12 hours, would be when day and night are equal.
Looking at http://www.timeanddate.com/worldclock/astronomy.html?n=110 and searching for March for various places, I find the following when the day length is close to 12 hours:
Jerusalem, Israel - Mar 17, 2013
Toronto, Ontario, Canada - Mar 17, 2013
Dallas, Texas, United States - Mar 16, 2013
Sydney, New South Wales, Australia - Mar 24, 2013
Nukualofa, Tonga - Mar 26, 2013
Caracas, Venezuela - Mar 9, 2013
As you can see, the point when daytime is equal to nighttime varies considerably around the globe. I'm not sure I found the extremes since I don't completely understand it.
The new moon could have occurred between March 9 and March 26, within the ranges of the vernal equinox. Those with early dates for the equinox would then count the occurrence of the new moon as the beginning of the new month. However, those with the later dates for the vernal equinox would have to wait until the next new moon, since the new moon happened before the equinox.
Am I thinking through that part correctly?
Just found a later date:
Manaus, Amazonas, Brazil - May 1, 2013
That's about 53 days difference! There exists some years where two new moons would occur within that time frame.
The Jewish calendar begins on the new moon after the vernal equinox. Whether you go by the real new moon or the sighting of the new moon, it shouldn't make much difference to the relationship.
The equinox can be defined when the sun is in the same plane as the earth's equator. This would occur at a precise theoretical point. I've also seen it defined when the amount of daylight equals the amount of night.
Is it possible for people in Jerusalem during Bible times to know when the sun is at the plane of the equator, that the day and night portions are the same at the equator, of which would be different in Jerusalem?
Or is it when the day and night lengths are equal in Jerusalem? I read that given an east-west line, such as a road, when the sun sets dead centered on it, that is when the day and night are equal.
Does this happen everywhere at the same time? If a day is 24 hours, then when the daylength is 12 hours, would be when day and night are equal.
Looking at http://www.timeanddate.com/worldclock/astronomy.html?n=110 and searching for March for various places, I find the following when the day length is close to 12 hours:
Jerusalem, Israel - Mar 17, 2013
Toronto, Ontario, Canada - Mar 17, 2013
Dallas, Texas, United States - Mar 16, 2013
Sydney, New South Wales, Australia - Mar 24, 2013
Nukualofa, Tonga - Mar 26, 2013
Caracas, Venezuela - Mar 9, 2013
As you can see, the point when daytime is equal to nighttime varies considerably around the globe. I'm not sure I found the extremes since I don't completely understand it.
The new moon could have occurred between March 9 and March 26, within the ranges of the vernal equinox. Those with early dates for the equinox would then count the occurrence of the new moon as the beginning of the new month. However, those with the later dates for the vernal equinox would have to wait until the next new moon, since the new moon happened before the equinox.
Am I thinking through that part correctly?
Just found a later date:
Manaus, Amazonas, Brazil - May 1, 2013
That's about 53 days difference! There exists some years where two new moons would occur within that time frame.