Catch the brightest luminaries
Winter, spring, summer or fall, there’s always a blockbuster overhead on any clear night.
Mercury still clings to the west-southwest horizon a half-hour or so after sunset at week’s end. It is surprisingly bright, but you may need binoculars to pick it out amidst twilight’s glare. Catch this one while you can, as it’s on its final showing.
Sunset finds Jupiter high in the east, easily the brightest nighttime object other than the moon, which pays the gaseous giant a visit early next week. Whereas Earth has but one moon, the king of planets has more than 60 moons, four of which you can see through a small telescope or even binoculars. Io and Europa are roughly the size of our moon, while Callisto and Ganymede are half again as large. In fact, Ganymede is larger than Mercury.
By 9:30pm, Jupiter is almost directly overhead, surrounded by The Great Winter Circle, an asterism of seven of the 25 brightest luminaries. Just to the east of Jupiter are the Gemini twins Castor and Pollux, the 23rd- and 17th-brightest stars respectively. Shifting your gaze clockwise to the north you’ll find golden Capella, the sixth-brightest star. Continuing now to the southwest, look for Aldebaran, the red eye of Taurus the bull, the 14th-brightest star. From there, look to the south for Rigel, the foot or Orion the hunter and the seventh-brightest star. You’ll find the brightest star of all, Sirius of Canis Major, at the southern edge of the circle, followed to the east by Procyon of Canis Minor, the 8th-brightest star. Within the Circle but not part of the actual asterism is the 11th-brightest star, Betelgeuse, marking Orion’s shoulder. The waxing gibbous moon is also within the Circle throughout much of this week.
Mars rises around 11pm and is less than five degrees from Spica, the 16th-brightest star in the heavens. As daybreak nears, the two are high in the south. Trailing behind the two and rising 90 minutes later is Saturn, a steady golden light as bright as the average star.
Finally, in the hour before sunrise, the brightest star-like object crests the southeast horizon. Nothing aside from the sun and moon outshines Venus, which is at its most brilliant this week, although it will remain a fixture in our pre-dawn skies until autumn.