This Week’s Sky at a Glance, 2020 January 4 – 11 ~by Curt Nason
Around midnight in the first week of January the brightest star in the night sky is due south, at its highest above the horizon. Astronomers would say it is transiting the meridian when it crosses the north-south line. Many 19th century observatories, including the one now called the William Brydone Jack Observatory at UNB Fredericton, would collaborate in timing the transits of stars to determine the longitudes of the observatories.
Sirius is called the Dog Star because is part of the constellation Canis Major the Great Dog, one of Orion’s hunting companions. If you are unsure which star is Sirius, follow Orion’s Belt down to the left. The star is about twice the size of the Sun and 25 times more luminous, but that is not why it is the brightest. It is only 8.6 light years away, a mere 82 trillion kilometres, and the nearest naked eye star for us in New Brunswick. The name means “scorcher” or “scintillating one” and it often twinkles wildly and colourfully, especially when it is lower in the sky. I like to observe it with binoculars or a telescope just to enjoy the light show. Look for the star cluster M41 about a binocular field below Sirius. With the Sun passing above Orion in summer, people once believed the hot days were due to extra heat from Sirius, hence the term “dog days of summer.”
This Week in the Solar System
Saturday’s sunrise in Moncton is at 8:01 am and sunset will occur at 4:46 pm, giving 8 hours, 45 minutes of daylight (8:03 am and 4:54 pm in Saint John). Next Saturday the Sun will rise at 7:59 am and set at 4:54 pm, giving 8 hours, 55 minutes of daylight (8:01 am and 5:02 pm in Saint John). On Sunday Earth is at perihelion, when it is closest to the Sun for the year; a whopping three percent closer than in early July.
The Moon is at first quarter on Friday, January 3, and it is full the following Friday. Mars crosses the constellation border into Scorpius this week, and within a week it will be a binocular field above its namesake star, Antares, which means “rival of Mars.” They often have similar colour and brightness, although the star is currently brighter than the planet. Setting around 8 pm this week, Venus passes over the tail stars of Capricornus the Sea Goat and enters Aquarius next weekend. The brief Quadrantid meteor shower, with its radiant between the handle of the Big Dipper and Hercules, peaks this Saturday morning (January 4). With no Moon in the sky to wash out these typically faint meteors, this shower could make it worthwhile to visit an area relatively free of light pollution.
The Saint John Astronomy Club meets in the Rockwood Park Interpretation Centre on January 4 at 7 pm. The annual Irving Nature Park Moonlight Snowshoe Hike and Observing takes place at the Sheldon Point barn in Saint John on January 11 at 7 pm.
Questions? Contact Curt Nason.