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Follow the arc to the star Arcturus in May


Tonight for May 7, 2015

Now is the perfect time to look outside in the evening and learn a phrase useful to sky watchers. The phrase is: follow the arc to Arcturus.

First locate the Big Dipper asterism in the northeastern sky. Then 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, known in skylore as the bear guard.

Arcturus is a much larger star than our sun. Read more about Arcturus here.

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.

So that’s how to “follow the arc” to the star Arcturus in the constellation Bootes. Learn how you can drive a spike to the star Spica – and the planet Mars – in the constellation Virgo with the help of tomorrow’s sky chart.

Big and Little Dippers: Noticeable in northern sky

Arcturus: Follow the arc

Spica is a whirling double star