Full, then New, then Full, then Eclipse

I believe that an “email blast” has gone out today about my Under-Standing of Eclipses, which of course you need in preparation for the great event of August 21.  So here is the Moon,

rolling along toward that appointment it has with the Sun, just a month and a half ahead.  The Moon – Full on July 9 at 4h Universal time – is, in this picture, rolling almost along the horizon, because I have chosen, for a change, to draw an Arctic scene.  (Something in a comment by a reader – though I can’t at the moment find it – suggested drawing the Moon’s path as seen from the north pole.)

From Arctic latitudes, the celestial equator becomes flattened toward the horizon, and so does the ecliptic (though unsymmetrically because it cuts the equator at an angle), so the moving bodies also take more horizon-like courses.  But if we showed the scene from the north pole itself, in summer, the whole sky would be in daylight, so I’ve moved the viewpoint down to latitude 66#, barely south of the Arctic Circle.  The time is local midnight (renamed “1 AM” by Daylight-Shifting Time”), so the Sun is barely below the horizon on the opposite side, behind your back.  And the Moon is passing the opposite “anti-Sun” point, in other words, is Full.

The Moon is shown at twice its real size.  And it is shown with parallax, that is, displaced southward as seen from far north on the Earth.  The arrows connecting the Moon’s position from day to day are not displaced for parallax, so they give an idea of where the Moon would be if you were looking from the center of the Earth.

Though Pluto is far too faint for the naked eye, we show it since it also near the anti-Sun point, that is, at opposition, on July 9.  Even if you had an excellent telescope and the skill, you wouldn’t choose to look for it on this day of opposition because it would be in the glare of the Full Moon; nor might you choose to look for it from the Arctic Circle.


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