Thursday, February 14, 2013

Saturn's 2-year celestial path, and ring angle



Event Date: February 22nd
Time: 4:37(.56) AM


Brief

   Saturn has crept further south of the celestial equator rapidly over the last two-plus years: first, when approaching western Virgo where the Sun is at the September equinox; also after leaving this longitude and moving through Virgo towards the constellation of Libra.  Only its retrogrades have brought it a little further north.  As we approach its upcoming opposition in late April, that will be preceded by another retrograde beginning.  The celestial path of Saturn over the last two years is shown below, with the increment markers for every 30 days. 





Detailed

  Notice above, how each retrograde has brought it back north, and each prograde back south.  Looking closely at image one, there is a slight "loop" in the celestial path; this a result of our orbit not inclined the same way Saturn's is and therefore, it changes in ecliptic latitude slightly.  Also for each Saturn retrograde, there seems to be slight "wobble" in the rings, although it takes several days to notice.  During prograde motion over the last few years, we have seen the ring angle to our eyes improve, while getting slightly worse during retrograde.  A few years ago, we viewed Saturn straight towards its equator and the rings spent a few weeks appearing nearly "edge-on".  Now, we are viewing the planet while it is at a celestial longitude allowing us to see more of the rings.  Therefore, that reflected Sun off of the icy [particle] rings makes Saturn appear a little brighter than average at oppositions.  Take a look here, and notice that we are viewing it nearly halfway between its equator and pole.  Its Moons and a couple of dim stars of similar magnitudes (unlabled) seem scattered about around Saturn, instead of in-line. 


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





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