Mercury and Venus near [star] Graffias

Event Date: December 17th

Time: 6:30 AM

Brief

   After an impressive apparition for Mercury over the last few weeks, the elusive planet is starting to catch up with the Sun faster a little more each day, while barely brightening.  The result of this eventually, is a much smaller gap between the two rising, and Mercury falling into the glare of the Sun.  With the geometry of the eastern half of the sky starting to worsen, it means that Mercury will no longer be north of the Sun during its last days of being visible to us on Earth.

   Seen below, is the planet with its orbit and the celestial guidelines.  As we see from the ecliptic's angle with the horizon, it no longer forms the steep angle that it did during mornings between late September and early November.

Detailed

   As Mercury speeds up in prograde motion, it further separates from Venus, albeit gradually.  Venus also has started to pick up speed in prograde gradually, as it reaches superior conjunction as well in a few more months.  The gap between Mercury and Venus rising with the Sun are 80 minutes and about 2 hours respectively  As a result of being near aphelion, Mercury as pulled a little further away from us while waxing.  Therefore, the angular area of light reflecting from its disc to our eyes, has barely changed.  Also, looking at Mercury's ecliptic latitude, is slowly becoming less north, as our angle wiewing its orbit changed.

   Finally, look between Mercury and Venus, just a little east (bottom left) of the latter: Mercury passed very close to this star, Graffias, back on the 13th.  Next, Venus has a chance to pass close to the star in separation.  I will show the separation zoomed in tomorrow, yet it is already impressive this morning.  A zoom-in of the two planets and star are shown here, in a 9º, wide binocular field.

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