This Week’s Sky at a Glance, Dec. 31–Jan. 7 ~by Curt Nason
Have you made a New Year’s resolution? I never make them but I do set astronomy goals such as the number of days I do observing, and spotting Mercury at least once in each of its six or seven apparitions during the year. In astronomy the word resolution has another meaning: seeing two closely paired objects as separate entities, most often used in reference to double stars. They can be naked eye, binocular or telescopic doubles, and resolving or “splitting” them is a popular challenge for stargazers.
Many of you have already tried splitting a naked-eye pair – the middle star in the handle of the Big Dipper. Under reasonable conditions most people can detect Alcor beside brighter Mizar after a few seconds of concentrated viewing. Doing so was once used as a test of visual acuity, an early eye chart, and the pair has been called “the horse and rider.”
Albireo, which marks the head of the swan in Cygnus, is a colourful double star that is split with binoculars. Their blue and yellow hues are seen more easily with the binoculars slightly out of focus. A favourite of mine is Nu Draconis, the faintest of the four stars in the head of the dragon, which resembles cat eyes or headlights in binoculars. In nearby Lyra we find another popular and challenging target. Beside the bright star Vega, and in line with the right side of the parallelogram that forms the body of the harp, is Epsilon Lyrae. To the eye it is a single star and with binoculars it is a pair, but with a good telescope and a steady sky each of that pair can be resolved as two stars, earning Epsilon the moniker “Double-Double.” This goes well with the constellation’s other highlight; the Ring Nebula (M57), which resembles a doughnut.
This Week in the Solar System
Saturday’s sunrise in Moncton is at 8:02 am and sunset will occur at 4:44 pm, giving 8 hours, 42 minutes of daylight (8:04 am and 4:52 pm in Saint John). Next Saturday the Sun will rise at 8:01 am and set at 4:51 pm, giving 8 hours, 50 minutes of daylight (8:03 am and 4:59 pm in Saint John). Earth is at perihelion mid-morning on Wednesday, when it is closest to the Sun for the year. The Supersun will appear 6% larger than it does in early July, but be safe and don’t look at it. If you really want to see a large Sun, wait for it to enter its red giant stage in several billion years.
The Moon is at first quarter on Thursday, giving great views in a scope later in the week. Mars takes centre stage in the solar system this week, passing very closely below Neptune on Saturday evening and remaining within a binocular view all week. A scope or hopefully binoculars should show them together this weekend. The Moon joins them early in the week, and Venus is not far away. Jupiter and Spica make an attractive couple in the morning sky. Early Tuesday the sometimes-active Quadrantid meteor shower is near its peak, shooting meteors from above the handle of the Big Dipper.
The Saint John Astronomy Club meets on January 7 at 7 pm in the Rockwood Park Interpretation Centre. All are welcome; no experience, telescope or money is necessary.
Questions? You can contact Curt Nason here.