Courtesy of EarthSky
A Clear Voice for Science
Go out at nightfall and look to the east, you will see the beautiful planet Saturn. It will be the starlike object close to tonight’s almost-full waxing gibbous moon. Note Saturn’s golden color, if you can. If you cannot, try viewing this world through binoculars. Better yet, look at Saturn’s golden color and glorious rings through a telescope.
By about midnight, Saturn will be high in the southern heavens. Why Saturn and why tonight? Tonight Saturn is only one week past its opposition date to the sun. Unlike the obstinate defiance of an argumentative two-year-old, opposition is a good quality in a planet … albeit a quality that is only temporary. Since a planet at opposition is essentially opposite the sun, it is available for viewing all night, just as the sun is seen all day. And the orbital geometry demands that while in opposition, the planet is also at – or nearly at – its closest to Earth.
Of course, opposition is nothing special to Saturn. All outer planets reach opposition about once a year, except for fast Mars. Mars takes longer — about 780 days, but for the much farther and slower moving planets, it is little more than a year. For Jupiter, it is 398 days, whereas for Saturn it is just 378 days. It is actually Earth’s motion around the sun – in our smaller faster orbit – that brings Saturn to this place in our sky at the same date, plus roughly two weeks each year. (In 2011 it will be on April 3.)
Saturn is closer to us tonight than it will be for the rest of this year, hence its brightness.
Written by Larry Sessions