Coneheads

I saw the moon yesterday.

It suddenly occurred to me that the moon appears to ride the rainbow. Not that that is what I saw but it did seem to point out the obvious astronomical effects.

It was a nearly flat sided moon (first Quarter having just passed.) When the moon rises that slab side always stays in the same position as if a giant wind-sreen-wiper is attached to the middle of it.

For fist quarter, the flat edge is always closest to earth. Presumably for last or second quarter it is always flat edge up? In this case, as it was late afternoon, the moon was half way from the high point (mid-heaven) to the western horizon. You could almost see the arc it had travelled, it was that easy to imagine it.

From my point of view the line from somewhere behind my head to the moon, anywhere on its course that day, was like the top half of a cone. Someone stranded in Hawaii by the European air traffic chaos, would be looking up at the same sight, some 12 hours later, seeing the other side of the cone.

One more thing.

It can be difficult to explain the declination of the moon and sun. We know that it gets colder in northern climes because the declination of the sun is low in winter. The reason why it rises so late and sets so early is because the size of the arc of that conic section is so much smaller in winter.

But for the moon the size of that arc changes daily. Yesterday it seemed quite a large arc (I haven't checked the declinations) in two week's time though the arc will be much smaller.

Here is a depiction of the lunar declinations for 2006 from the Wikipedia:
http://upload.wikimedia.org/wikipedia/en/f/f9/LunarDec2006.png

Just to show you what sort of an expert I am:
Until today I had assumed that the Lunar Nodes were the tips of the curves. The highest and lowest points. It turns out they are the middle points, the parts around the zero mark.

Can you believe that?
What a plonker!

They are the equivalent of equinox not solstices.
Well I've learned something.
I don't know about you?

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2 thoughts on “Coneheads

  1. There is a lot of information about nodes from astological websites. In view of the importance one author places on the position known as "standstill" it is surprising the astrologers deem the nodes important:Originally posted by Wikipedia:

    At a major lunar standstill, which takes place every 18.6 years, the range of the declination of the Moon reaches a maximum. As a result, at high latitudes, the Moon appears to move in just two weeks from high in the sky to low on the horizon.This time appears to have had special significance for the Bronze Age societies who built the megalithic monuments in Britain, Ireland, and it also has significance for some neo-pagan religions.Evidence also exists that alignments to the moonrise or moonset on the days of lunar standstills can be found in ancient sites of other ancient cultures, such as at Chimnney Rock in Colorado and Hopewell Sites in Ohio.

    The biblical reference appears early in the stories of the Exodus; when the sun stood still over so and so and the moon stood still over some place else.I suppose I'd better look it up?Originally posted by Joshua 10: 9 to 12:

    Joshua therefore came on them suddenly. He went up from Gilgal all night. Yahweh confused them before Israel, and he killed them with a great slaughter at Gibeon, and chased them by the way of the ascent of Beth Horon, and struck them to Azekah and to Makkedah.It happened, as they fled from before Israel, while they were at the descent of Beth Horon, that Yahweh cast down great stones from the sky on them to Azekah, and they died. There were more who died from the hailstones than who the children of Israel killed with the sword.Then Joshua spoke to Yahweh in the day when Yahweh delivered up the Amorites before the children of Israel; and he said in the sight of Israel, "Sun, stand still on Gibeon! You, moon, stop in the valley of Aijalon!"

    The physics is the same as for top and bottom dead centres in motor engineering. The piston is only at top or bottom dead centre of the stroke for the same time that it is at any other part of the cylinder. But it is at the adjacent points twice in almost immediate succession; once going to the tip and once coming back.A lot of the engine's "slack" is also expressed in the system at this time adding to the phenomenon. Such slack doesn't apply to the liquid motion of the planets.Any take up in the engineering is seen as a lapse in the processions. Or is it precessions?

  2. There IS slack in the system though. There has to be. A planet the size of the moon is much too great to be slowed by small discrepancies in gravitational attraction brought about by MASCONS, small anomalies in the make up of the planets near enough to their surfaces to be detected.Heavier or lighter substrate. Lots of it, all in one place.There is enough to cause a bumpy ride and maybe the weather and earthquakes. Even volcanic activity?

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