You can use the bright orange star Arcturus – and learn a playful phrase useful to skywatchers – to help you be certain you are identifying the planet Saturn in 2012. Scouts learn this phrase. Grandparents teach it to kids. It was one of the first sky tools I learned to use in astronomy.
The phrase is: follow the arc to Arcturus and drive a spike to Spica.
Follow the arc to Arcturus and drive a spike to Spica
Saturn is easy to spot in April 2012 skies, but – if you’re a beginning skywatcher – you might have some uncertainty that the object you’re seeing is Saturn. That’s where Arcturus comes in. Once you find the star Arcturus, you are on your way to finding the star Spica, as the chart at the right shows. In 2012, golden Saturn is quite close sparkling silvery-blue Spica in the eastern sky on April 2012 evenings. Read more: Give me five minutes, I’ll give you Saturn
Here’s how to use the phrase to locate Arcturus. First locate the Big Dipper asterism in the northeastern sky in mid-evening, maybe around 9 p.m. It is very easy to see, a large noticeable dipper-shaped pattern in the northeast in the evening. Can’t find the Big Dipper? Look to our chart for April 6.
Once you can see the Big Dipper, notice that it has two parts: a bowl and a handle. Then, with your mind’s eye, draw an imaginary line following the curve in the Dipper’s handle until you come to a bright orange star. This star is Arcturus in the constellation Bootes the Herdsman. Arcturus is known in skylore as the Bear Guard.
Arcturus is a giant star with an estimated distance of 37 light-years. It’s special because it’s not moving with the general stream of stars in the flat disk of the Milky Way galaxy. Instead, Arcturus is cutting perpendicularly through the galaxy’s disk at a tremendous rate of speed . . . some 150 kilometers per second. Millions of years from now this star will be lost from the view of any future inhabitants of Earth, or at least those who are earthbound and looking with the eye alone.
But for now Arcturus is one of the easiest stars to find, using the Big Dipper as a guide. And, in 2012, once you find Arcturus, you are on your way to finding Saturn. Try it, on a lovely spring evening soon.
