What’s Up In the Sky - May 2010

Fred Barrett | Apr 29, 2010

By Fred Barrett

The constellation Virgo is prominent in the South at mid-evening this month. In many cultures she is identified with purity, maidens and fertility. In ancient times she was a goddess who represented the harvest and growing crops. It is especially suitable then that Virgo can be easily found via the star Spica, which has the meaning “ear of wheat”! Alpha Virginus or Spica is the most noticeable star at the bottom portion of Virgo. Typically, the brightest star in a constellation is designated by the Greek letter alpha. To find Spica go outside at about 10PM and face south. Wait for your eyes to dark adapt, then, with your arm stretched out, count up five or six fist widths (50 or so degrees) from the horizon. You’ll find yourself in a sky neighbourhood where nearly no other bright stars are found. Spica’s brilliance should leap out at you. Another way to find Spica is to use the saying “Follow the arc to Arcturus, then speed on to Spica”. Find the Big Dipper and follow the arc of its handle about 25 degrees past the last star in the handle. You will find yourself at the bright star Arcturus in Bootes. Now speed on for another 25 degrees in the same arcing direction and there you’ll be at Spica. Make up your own little navigation tricks to help you find your way around the night sky!

A fact to note about Spica is that it is a double or binary star at a distance of 260 light years. What is especially interesting is that it is separated from its companion star by only 13 million miles (21 million km). When you consider that Earth is 93 million miles from the Sun, you can get an idea of how very close the two stars orbit each other. It takes a mere 4 days per orbit! As you can see in the star chart, there are quite a few Messier objects in the upper right quadrant. These are all galaxies and most belong to the Virgo Supercluster. The most famous is the giant elliptical galaxy M87 in the middle. It is a strong radio source and is thought to harbor a black hole at its centre. The Supercluster contains a lot more galaxies than the little Local Group of galaxies that we belong to. Down in the right quadrant is M104, the Sombrero Galaxy. This attractive galaxy is an edge-on galaxy that gets its name from the hat that it resembles. You will need at least a modest-size telescope to see all these objects; a 4-inch aperture would do the trick. But that doesn’t mean that there aren’t some beautiful binocular sights to discover.

I hope you got a view of Mercury near Venus last month because it’s hidden in the Sun’s glow now! Venus, on the other hand, is shining brightly in the West North West as twilight fades and it’s slowly rising up to become our “Evening Star” for the summer. Mars is still with us and can be found in Leo high in the West in mid evening. It is slowly edging in on Regulus. (Check last month’s column for information on Leo. You can retrieve it from The Frontenac News handy website archives: frontenacnews.ca/2010/10-13_apr_1/whats_up_10-13.html.)

High in the South, Saturn is still a beautiful sight with its shifting moons scattered around it. The rings are tilted at only a small 2 degree angle but spectacular even so. Jupiter is low in the East at dawn but is getting higher as the weeks pass. By autumn it will be a wonderful binocular sight by mid-evening. I especially love watching its moons dancing around it from evening to evening. Stay tuned and I’ll keep you up to date on its progress.

A waning slim Moon passes near Jupiter on the 9th just before dawn. Watch for the crescent Moon below Venus on the 15th and above it on the 16th at dusk. Nice sights! This month’s full Moon occurs on the 27th and is known as the “Flower Moon” because, well, there are flowers everywhere!

There is a meteor shower this month, the Eta Aquarids. It peaks about 3AM on the 6th but a bright last quarter Moon ruins that peak. Still, there will be an increase in the number of meteors to be seen throughout the night. If you are out that evening, look for them in the darker areas of the sky.

The Sun rises around 5:40AM and sets about 8:10PM early in the month. By the end of the month that changes to 5:20AM and 8:40PM.

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..