Thursday, February 20, 2014

The Moon's Node and Portable Stonehenge

Thursday (today) the moon crosses its north ascending node.  The node, one of two, is where the moon's orbit intersects the earth's orbit (or the sun's ecliptic).  If the moon were full, we'd have a lunar eclipse; if the moon were new, there'd be a solar eclipse.   I'd read that this would happen on EarthSky, and when I went to check my Portable Stonehenge, I saw that I'd managed to keep it more or less in sync with what was actually going on in the sky.

In this photo of Portable Stonehenge, I lined up a window frame's shadow so that it fell across the two pegs on the inner circle representing the moon's nodes.  The peg closest to the camera is the Moon peg, and it's showing Wednesday's position.  At about the two o'clock position is the Sun peg.  The peg in the center is a day marking peg that I use to keep track of when to move the Sun peg (twice every thirteen days).

Sometimes I think it would be fun to have a large version of this in our back yard or in a public plaza, but then I imagine that the markers for the day, moon and sun would get knocked over or be in the way.  Maybe some day I'll get enough hooks that I could do a square version of this for a room and hang them along the upper corners of the walls.
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