Follow the arc to Arcturus
Print Me Email to FriendTonight's Sky for Monday, Mar 24 2008
It’s now the perfect time to look outside in the evening and learn a phrase useful to skywatchers. Scouts learn it. 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.
First locate the Big Dipper asterism in the northeastern sky in mid-evening, maybe around 9 p.m. Can’t find the Big Dipper? Look back to our chart for March 7.
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, 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. Try it, on a lovely spring evening soon.
I live in India Mumbai. I saw an extremely bright star at 1 am. Is it the Arcturus. Keep in mind my time zone.
Hi,
just wrote to you, asking about the Arcturus. I was facing the west. Hope thats of help.
Hey its me once again, Suneeta. I saw this at 1 am on the 7th march 2007. The top spike of the star kept moving like a flame up and down. It was an awesome sight. I really need help to know if it was the arcturus i had seen. I live in Mumbai India and my window was facing the west.