| Apr 28, 2011


By Fred Barrett

Let’s have a look at Corona Borealis this month. It’s a small constellation and can be found between the constellation Bootes to its right and Hercules to the left. I hope some of you, using the techniques I mentioned last month, had a chance to practise finding your way around the night sky. To arrive at Corona Borealis we must first find Bootes. Look to the Big Dipper and follow the arc of its handle down about 20 degrees (two fist widths) to the bright, slightly orange star Arcturus. Bootes is about the same size as the Big Dipper and shaped like a kite. Arcturus sits at its bottom where a tail would be attached on a kite. Now follow the outline of Bootes up to its wide part and look left (east). You will see the U shape of the Corona Borealis. Its main stars form a semicircle that resembles a crown. In Latin, its name means the “northern crown”. In early May you can find the Crown about an hour after sunset towards the southeast. It will shift slowly towards the south as the month progresses.

In Greek mythology the constellation was considered to be the crown that the god Dionysus gave Ariadne, the daughter of King Minos of Crete, when she married him. He tossed the crown into the sky after the wedding and the jewels turned into the stars of the constellation. The Cheyenne first nation calls it the “Camp Circle” since it resembles the way they set up camp in a semicircle. In Welsh mythology it’s known as the Castle of Arianrhod and is her home in the heavens. Australia’s aboriginals call it ‘Woomera’ or the Boomerang and the ancient Chinese called it Kwan Soo, meaning “a cord”. Although small, it’s an exquisitely beautiful sight in the sky and that may explain why so many societies past and present have a name or story to describe it. By the way, three of its stars are known to have planets!

Corona Borealis doesn’t have any prominent deep space objects but its surrounding area is fascinating to explore with binoculars. It’s worth getting a star chart and investigating some of the double and variable stars in its neighbourhood and good practice for learning the night sky too! Soon (sooner the better) it will be getting warm enough to lie back on a blanket with binoculars and roam the skies.

Low in the eastern dawn sky about 30 minutes before sunrise is an exciting direction to observe this month! The tightest grouping of four planets in decades will be on display. They are Mercury, Mars, Venus and Jupiter. You will likely need binoculars to make out Mercury and Mars in the grouping. It will be fascinating to follow their shifting positions as the month progresses. The crescent moon joins the grouping on the 1st and 2nd of the month and again at the end of the month on the 29th, 30th and 31st. Saturn is still easy to find above bright Spica in Virgo in the southeast.

The Aquarid meteor shower peaks in the early morning of the 6th. It will be active a few days before and after that date. Because of the way the Earth is intersecting this debris from Halley’s Comet, not many meteors will be seen this far north. Nonetheless, it’s worth a look. The moon will be low and won’t interfere.

The Full Moon falls on the 17th this month and is called the Flower Moon.

The days are getting longer and dark nights for astronomy shorter. Early May sees the sun rising at 5:40AM and setting at 8:15PM. By the end of the month dawn occurs at 5:17AM and dusk at 8:38PM. All times are in daylight savings time and approximate.

Saturday, May 7 is International Astronomy Day. Check www.rasc.ca/astroday or your local newspaper for events. Since I’m not sure yet whether to set up my own session or take part in a larger group event, please email me for last minute information. 

 

If you have questions or suggestions, Fred Barrett may be contacted at This email address is being protected from spambots. You need JavaScript enabled to view it.

The Beginner’s Observer’s Guide by Leo Enright is available at the Sharbot Lake Pharmacy or by contacting the Royal Astronomical Society of Canada www.rasc.ca/publications, subscriptions for our very own excellent Canadian astronomy magazine, Sky News, are also available from RASC..

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