Tuesday, February 7, 2012

Planetary Aperçus: Featuring Saturn and Uranus

Spoken literally from the French, aperçu is an "outline or summary" or even a "glimpse," which is what this article will give you: an impression of two planets, although rather dim when viewed by the naked eye.


This Wednesday, February 8, 2012, Saturn will begin to go retrograde. It rises around eleven pm to midnight, in the east, and reaches the zenith around 5 am. At that time, Saturn will be seen in Virgo, west of Spica (although it will vary among locations). Its retrograde period will signify better viewing, as it will rise earlier. "Saturn will be rising earlier each evening with each passing day. It’ll soon be in a more convenient place for evening viewing," EarthSky.com reminds. Saturn will be at magnitude 0.5, so spotting it shouldn't be that hard.

What is, precisely, retrograde motion? Covered in detail when Mars went retrograde in January 2012, apparent retrograde motion is the visible, backward orbit of a planet as viewed from earth, due to the orbit of that planet. On account of the fact that earth orbits quicker than other planets (particularly the outer planets; although the inner planets (Mercury and Venus) exhibit it rather differently), earth, from time to time, will "overtake" a planet of note (such as Saturn), causing that planet to look as if it travels in reverse, periodically being motionless for a few days before and after the event. As earth then passes the planet again, we can see that it resumes its old orbit (which is normal: west to east). [There is a visual at the Mars link above]

Saturn will be at opposition April 15, 2012. Opposition is literally when Saturn is closest to earth, and brightest in the sky, but until then, Saturn's retrograde is a spectacle! Early June marks the end of Saturn's retrograde motion. Read more about Saturn from EarthSky.com. From NakedEyePlanets.


So vibrant will be these two planets over the next few days. Venus has been shining strong, being the second brightest object in the night sky at magnitude -4.1 (although it will be brightest when the moon goes new), and now, just 0.3 degrees beneath it will be Uranus, bluish-green! Interesting to note, Uranus shines at magnitude 5.9, almost 10000 times dimmer than Venus!, and the brighter will lead you to the dimmer. Both planets are presently in Pisces.

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