(SNES) Adding and Subtracting at Dusk and Dawn - or why I can't see Mercury after dark.

["Les Coleman" <les11@cox.net>]

I was considering an attempt to view Mercury in my telescope today using a long dew shield
to keep the Sun's glare out since the two objects are only about 5 degrees apart. It didn't
looking very promising in spite of Ed Magowan's recent success, so I considered getting up
early to see Mercury before the Sun rose. However, because the angle that Mercury currently
makes with respect the the ecliptic is about 22.5 degrees, an odd thing happens. 22.5 is
just about the same angle as the tilt of the Earth (the obliquity of the poles). In the
morning, the two bodies rise at the difference of the two angles (or just about 0). In the
evening the two bodies set at the sum of the angles (roughly 45 degrees). Thus in the
morning the two bodies rise together but in the evening the Sun sets a full 25 minutes
after Mercury.

In the vast scheme of the universe, this really is not a matter of any significance but it
is one of those things that fascinate me.

Les Coleman
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