Sky at a Glance August 5 – 12

Photo of the Constellation Perseus showing the location of the Double Cluster and other wonders.
This Week’s Sky at a Glance, August 5 – 12   ~by Curt Nason

With the Perseid meteor shower increasing nightly to a peak next weekend, let us visit its namesake constellation. Perseus the Hero starts rising in the north before sunset now and by midnight he stands on the northeastern horizon, just below the W shape of his mother-in-law, Cassiopeia. He is a hero because, among other deeds, he prevented his near-future wife Andromeda from becoming a tasty lunch for a ferocious sea monster.

The brightest star in Perseus, Mirfak, is part and namesake of the Alpha Persei Cluster. This is one of my favourite binocular targets because it resembles a miniature version of the constellation Draco. Another popular binocular target is a close pair of star clusters located halfway between Perseus and Cassiopeia. Astronomers have cleverly called this the Double Cluster. The Perseid meteors all appear to originate from a point, called the radiant, to the left of the Double Cluster.

The constellation’s second brightest star is Algol the Demon, representing the eye of the Gorgon Medusa. Perseus beheaded the Medusa in a plan to avenge an embarrassing moment by using her head to turn his hecklers into stone. The sea monster was his first victim of this weapon. Algol is famous for dimming by a factor of three every 69 hours. It is a very close pair of stars orbiting each other in our line of sight, and their combined brightness drops when the dimmer star passes in front of the brighter one. Look for the star cluster M34 about a binocular width above Algol.

This Week in the Solar System

Saturday’s sunrise in Moncton is at 6:06 am and sunset will occur at 8:43 pm, giving 14 hours, 37 minutes of daylight (6:13 am and 8:45 pm in Saint John). Next Saturday the Sun will rise at 6:15 am and set at 8:32 pm, giving 14 hours, 17 minutes of daylight (6:22 am and 8:35 pm in Saint John).

The Moon is full on Monday, the Mi’kmaw Ripening Moon. Mercury is moving sunward and sets 45 minutes after sunset by midweek. Jupiter is sinking lower in the west at dusk, setting before 11 pm midweek and approaching Spica nightly. Saturn, in the southern sky in evening twilight, makes an interesting colour contrast in binoculars with orange Antares to its lower right. Venus is the bright Morning Star, rising around 3:15 am among the stars of Gemini. The Perseid meteor shower peaks on the afternoon of August 12 and should make its presence known later this week. Moonlight will wash out the fainter meteors but take some time on a clear night to enjoy the show.

The Saint John Astronomy Club meets in the Rockwood Park Interpretation Centre on August 5 at 7 pm. All are welcome. The Mount Carleton Star Party runs from August 11 – 13; a great place to spend the weekend. Just think of how much closer you will be to the meteors.

Questions? Contact Curt Nason.

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