Jupiter in retrograde, nearing open clusters

Event Date: December 29th

Time: 9:57(.34) PM

Brief

   Over the last 4 weeks, since Jupiter's opposition, the combination of its retrograde motion and the Sun's continuous motion west to east against the stars, has brought the planet closer to our star by slightly over 1º a day; they have gone from 180º apart at opposition, to 149º apart.  When the two are eventually 90º apart, it means that Jupiter will be at eastern quadrature, followed by conjunction a few months later.  Here is where Jupiter is now, seen in image one high in the sky, with both clusters labled and the Hyades stick figure showing.  The second image shows the planet's celestial path over the last six months.

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

Detailed

   As a result of our perspective towards Jupiter, we don't see a "loop" as we sometimes do when a planet is seen switching directions.  Sometimes the loop leads to us seeing it change ecliptic latitude by as much as 2-3º, yet not this time.  As a result, we see the 10-day increment markers overlapping each other.

   Also with the retrograde, Jupiter has passed by the Hyades star cluster for the second of three times, and getting a little closer to the Pleiades.  With about a month left of retrograde, slowing to stationary as it further approaches the Pleiades, Jupiter will be a fun sight with binoculars, passing by these clusters.  

   For quadrature, which I glazed over in the brief, it means that there is 90º of separation between Jupiter and the Sun.  As is the case Moon is at--or very near--quadrature with the Sun when it is 1st or 3rd quarter, Jupiter is at or near transit when the Sun is rising or setting for western or eastern quadrature respectively.  Of course with the Moon, it orbits us, whereas Jupiter orbits the Sun.  Therefore, we will not see a half-illuminated Jupiter when it reaches quadrature; it is much too far from us in comparison to the Moon, to see such a change of phase.  Instead, Jupiter wanes very slowly to a still big-waxing gibbous around the low-90% range.  Then, as it gets closer to conjunction again, going behind the Sun (instead of between us and it), we have more of its disc reflecting Sunlight towards our eyes.