Venus and Saturn well paired--Mercury brightening

Event Date: November 26th

Time: 6:30 AM

Brief

   This morning, have a powerful telescope ready with a high magnification.  That is, even with the small field of an eyepiece providing over 50x magnification, Venus and Saturn fit nicely in a 1º field.  The field can be decreased further to capture their 0.7º separation.  Of course, the magnification can be increased further to see the rings of Saturn (not visible at 50x with the software), and the phase of Venus more easily as a tiny, waxing gibbous.  Alhough the software doesn't magnify either planet to see such detail in image two, I will show them anyway there, preceded by a zoom-in of the planets.  Mercury (+0.5 and quickly brightening) is present in the first one also with its orbit, to show that greatest elongation is not far.  

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   As Mercury moves a little further from perihelion each day, while we move slightly closer to the Sun each day for our own perihelion, that helps speed up its brightness.  Why?  Simple-- we are moving closer to the planet, so seeing slightly more surface area lit up, and more intensely.  There are times when we have the opposite in the spring and early summer; we are approaching aphelion and Mercury is approaching perihelion when nearing inferior conjunction.  Venus of course, while moving towards superior conjunction, brightens much more slowly than Mercury at some points in its cycle.  Venus can be decreasing quickly in illumination percentage while increasing in angular size, which happens before inferior conjunction as an evening target.  Venus wanes fast during those weeks, so somewhere in between, the planet reaches a maximum apparent magnitude.  Finally, Saturn as an outer planet, has the least change in apparent magnitude, not changing much in distance with us between opposition and conjunction.  Of course, the more attractive thing to look at with Saturn is its impressive ring-angle to our eyes, which I will come back to highly magnified, later in the month.