Bob Moler's Ephemeris Blog

Tuesday, November 16th.*  The sun will rise at 7:40.  It’ll be up for 9 hours and 33 minutes, setting at 5:13.   The moon, 3 days past first quarter, will set at 3:32 tomorrow morning.

This week we’re looking at selecting a telescope for a gift.  All things being equal, telescopes have two properties.  They are light gathering power and resolving power.  They are both related to the diameter of the primary mirror or lens.  Light gathering power is as it says the ability to see  faint objects.  Resolving power is the ability to see fine detail in an image so that more magnification can be used without producing fuzzy image.  This is a limitation that’s caused by the wave nature of light itself.  Also of equal importance with the optics is the telescope mount.  If it isn’t solid and smooth moving it makes the telescope useless.  Magnification in telescopes can be changed by using different eyepieces, so it is not an actual property of the telescope itself.

* Times, as always are for the Traverse City/Interlochen area of Michigan.