THE BEST TIME TO SEE SATURN

The best time to see the planet Saturn is here. April and May 2012 are when this golden world – planet of the rings – is easiest to spot and brightest. The best time to see the planet Saturn is here. April and May 2012 are when this golden world – planet of the rings – is easiest to spot and brightest. The planet Saturn is relatively easy to find in 2012, because it’s near a bright star, Spica, in the constellation Virgo. This star always returns to the early evening sky in April – spring for the Northern Hemisphere, autumn for the Southern Hemisphere. Spica stays out all night long – or nearly all night long – on April and May nights. Likewise, April or May of 2012 will also be the best time to see the ringed planet Saturn in all its glory. In 2012, you can follow the curve in the handle of the famous Big Dipper asterism to find the planet Saturn. Saturn in April 2012 Follow the arc to Artusus to identify Saturn in 2012 Drive a spike to Spica – and Saturn – in 2012 On April 15, 2012, Earth will pass between Saturn and the sun. That is why Saturn is at its best this year in April and May. In mid-April, Saturn will rise in the east as the sun sets in the west. Why? Because that is when Earth is passing between Saturn and the sun, and Saturn is opposite the sun as seen from Earth. Saturn closest, brightest, opposite the sun on April 15 Our Earth in its smaller, faster orbit around the sun is gaining on Saturn as we speak. We fly through space at some 107,000 kilometers per hour (67,000 miles per hour), in contrast to Saturn’s 35,000 kilometers per hour (22,000 miles per hour). So naturally there will come a time when Earth passes between Saturn and the sun. We do this every year, and, at such a time, we always see Saturn opposite the sun in our sky – rising in the east when the sun is setting in the west. Our passage between Saturn and the sun is called an opposition of Saturn. Why is the time around opposition the best time of year to see Saturn? Every year, around the time we go between the sun and Saturn, the ringed planet is at its closest to Earth and brightest in our sky. Saturn is the faintest of the bright planets. It’s still pretty bright, but, normally, you wouldn’t pick it out from among the stars. But around April or May of 2012 you can, because Saturn appears about as bright as the brightest stars. Because we’ll be passing Saturn – the sixth planet outward from the sun – from an inside track around the sun, the ringed planet will actually look as if it’s going backward (retrograde) in front of the fixed stars of the constellation Virgo from February 8, 2012, until June 26, 2012. This apparent westward (retrograde) movement of Saturn is really an illusion. If you were in a race car passing another race car from the inside track, you might glimpse the other car appearing to be going backwards for a time relative to background objects. It’s not really going backwards, of course. It only looks that way. In the same way, Saturn normally moves toward the east in front of the stars, but this outer planet appears to be going westward against the background stars for a few months every year, around the time of its opposition. By the way, Saturn’s yearly opposition happens about two weeks later with each passing year. The 2009 opposition was on March 8. The 2010 opposition was on March 21. The 2011 opposition was on April 3. The 2012 opposition is April 15. And the 2013 opposition will be on April 28. Saturn basics Earth travels around the sun once a year, while Saturn takes about 29-and-a-half years to orbit the sun once. Earth’s orbit is smaller, and we move faster than this outer planet. So once a year, we pass between Saturn and the sun and gain another lap on the planet. Golden Saturn as seen by the Voyager 2 spacecraft in 1980 You might realize from what I just said that Saturn is relatively slow-moving in orbit and, therefore, slow to change its position against the background stars. That’s why the early stargazers called it “the oldest of the old sheep.” Like all planets, Saturn is lovely to gaze upon. Its golden color is fascinatingly reminiscent of wonderful spacecraft photos of Saturn. It’s a real place, after all, not just a light in the sky. Plus, Saturn’s brightness waxes and wanes in a subtle way throughout every year, making it fun to watch. Can you see the rings of Saturn if you look with the eye alone? No, you need a small telescope to see the rings. But, to the unaided eye, Saturn will appear as a bright golden “star” … very beautiful. And unlike the twinkling stars, Saturn will shine with a steady light. That might help you identify it. I want you to see Saturn at its best in April and May 2012. On April 15, 2012, the Earth in its orbit will pass between Saturn and the sun, at which time Saturn will appear opposite the sun in our sky. So, in April and May 2012, if you’re looking for Saturn during the evening hours, you should be facing east to southeast at nightfall and south around middle to late evening. On any night of 2012 – because the planet Saturn stays close to the star Spica throughout 2012 – you can rely on the Big Dipper to guide you to Spica and Saturn. In other words, you can follow the arc to Arcturus and drive a spike to Spica from the handle of the Big Dipper. Once you identify Spica, notice the bright golden starlike object nearby. That’ll be Saturn. Saturn and Spica’s orientation with respect to the horizon will change throughout the year, and they are different in the Northern and Southern Hemispheres. But Saturn and Spica remain close during 2012. Two bright objects in the sky, near each other, might be them!