Mercury-Spica-Arcturus: "trio-up"!

Event Date: November 27th

Time: 6:30 AM

Brief

   As Venus and Saturn slowly start to separate, with the former moving much faster in pro-grade motion, we can notice that the pair is surrounded by yet, another triangle: two stars, one planet.  Of course, our actual Summer Triangle's stars are set below the horizon at this time of night, not-morning visible for about another 6-7 weeks (Altair being the last to rise).  Until then, notice that Arcturus, Spica and Mercury make a temporary triangle.  Mercury is catching up fast with Arcturus in apparent magnitude, as it approaches greatest western elongation.  The two stars of course, make up two-thirds of the Spring Arc asterism, which we recognize more easily as it is seen high in the evening during the namesake season.

   Here is the triangle below:

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

Detailed

   Mercury continues to brighten even after it passes greatest elongation.  However, Saturn's rising of about four minutes earlier means that it will pull away quickly, while Venus moves towards superior conjunction much more slowly that Mercury.  Watch the configuration of the triangle daily, as we reach the end of Mercury's western apparition; the triangle becomes expanded, with Mercury if thought as the apex, the "stretched out" point.  During this time, we see Venus slightly gain ground on Mercury moving west to east, until Mercury picks up much faster in prograde motion and pulls further away from Venus.  We also have another "visitor" to this part of the sky, visiting both planets and forming a much smaller triangle with them: the Moon!  We know that the Moon comes near the planets as it moves past the stars, and sometimes closer to the planets than others.  The waning crescent will reach this part of the sky early next month.