Monday, August 20, 2012

Uranus goes non-zodiacal...briefly!

Event Date: August 27th
Time: 3:14(.16) AM


Brief

After spending the last two evenings talking about Neptune, I will hop forward towards the Sun by roughly a billion miles (give or take), and now talk about Uranus.  In the constellation of Cetus, for limited time, this is normally the time of Uranus' revolution that we see it in Pisces.  However, because of the planet's ecliptic latitude swinging it a bit south of the ecliptic, from our perspective, it is just barely within the boundary of the sea monster.  There will be some back and forth on this over the next several months, as Uranus' retrograde-then-prograde motion has it cross the boundary a few times.
   The image here shows Uranus at transit within the Cetus boundary lines, It comes back to Pisces late this year, via retrograde motion, then back to Cetus for about a month early next year via prograde motion.  Notice when looking closely, how near Uranus is to the border, and how the unevenness of them can have us understand the back and forth irregularly.


Detailed


At about 1.8 billion miles from the Sun, Uranus takes about 84 years to revolve, and as a result of being so much further from the Sun than us, has a retrograde period of about 5 months.  This is compared to only a little over 2 months to our nearest outer-neighbor, Mars, and a little more than Jupiter and Saturn and around the 4-month mark for each.  For Uranus, which covers about 30º of sky every 7 years (equivalent to about one zodiacal sign for that duration), it gives most of us fortunate enough to live long enough, to see it make a complete revolution during our lifetime.  Since most of us likely won't understand the planets' movements against the stars until we are between 10-20 years old, if not beyond that span, it means an even longer time to have to live to consciously track a full Uranus revolution.  If you are one of those who remember exactly where Uranus was in the sky when you were a young age, via binoculars or a telescope, hopefully you have followed it ever year since, to really have a good perspective of what planets do, and how they earn their name as "wandering stars"!
   This second image shows Uranus with a star field of 1º, or about 50x in magnification.  Just as the case with Neptune in Aquarius, Uranus has a dim star field in Cetus, with most of the sea monster's "brighter" stars further south and east (while many are not much brighter than Aquarius'.


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







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