Here’s a useful phrase to stargazers to find the brilliant yellow-orange star Arcturus. 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. Here’s how 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. 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: follow the arc to Arcturus. Arcturus is the brightest star the constellation Bootes the Herdsman. This star 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.
Drive a spike to Spica Once you’ve followed the curve of the Big Dipper’s handle to Arcturus, you’re on your way to finding the star Spica. Just extend that same curve on the sky’s dome: drive a spike to Spica.
Spica is in the constellation Virgo the Maiden. It represents an Ear of Wheat held in the Maiden’s hand. By the way, the golden “star” below Spica at mid-evening is really the planet Saturn. Look for Saturn over the southeast horizon before going to bed tonight.
Bottom line: Use the curve in the handle of the Big Dipper to “follow the arc” to the star Arcturus. Then “drive a spike” to the star Spica. In 2013, you’ll find the planet Saturn to the east of Spica on the sky’s dome. Try finding these colorful celestial gems on a lovely spring evening soon.