This Week’s Sky at a Glance, 2021 August 7 – 14 ~by Curt Nason
With the Perseid meteor shower peaking this week, let us visit its namesake constellation. Perseus the Hero stands on the northeastern horizon by midnight, just below the W shape of his mother-in-law, Cassiopeia. He is a hero because, among other deeds, he prevented his 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 – NGC 869 and NGC 884 – located halfway between Perseus and Cassiopeia, which astronomers have cleverly called the Double Cluster. The Perseid meteors appear to originate from a point near 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 6:09 am and sunset will occur at 8:40 pm, giving 14 hours, 31 minutes of daylight (6:16 am and 8:43 pm in Saint John). Next Saturday the Sun will rise at 6:17 am and set at 8:29 pm, giving 14 hours, 12 minutes of daylight (6:24 am and 8:32 pm in Saint John).
The Moon is new this Sunday and it passes to the right of Venus on Tuesday. Mercury has entered the evening sky, setting 30 minutes after sunset midweek followed by dimmer Mars 15 minutes later. By the time Venus sets at 10 pm all eyes will be on Saturn and Jupiter in the southeast. Telescope users can catch Jupiter’s Red Spot around 9:40 pm Thursday. Wednesday evening to Friday morning is prime time for the Perseid meteor shower, which could be the best shower of the year because the waxing crescent Moon sets before 11 pm. Meteor rates of a third to half that of the peak times could occur on Tuesday and Friday nights, still better than many other showers.
Questions? Contact Curt Nason.