[Ham-Mac] Great Circle daylight/darkness App or Widget

[Dick Kriss]

I have a ham friend with a new Alu iMac who asked me to
recommend an application widget or whatever that displays
great-circle (not the Mercator) daylight/darkness.

He found one that is part of a $1000 plus special hardware
package that is out of reach.

I am not up to speed on Mac daylight/darkness utilities and
would appreciate anything someone is willing to share.  The
only utility I use is the freeware SunEarth Mercator widget.

73 Dick AA5VU