The Sky This Week from December 10 to 17

Tuesday, December 14

Let’s head back to Gemini again today, as the annual Geminid meteor shower peaks this morning with a waxing Moon in Pisces. That means bright moonlight will wash out the sky until about 3 A.M. local time (when the Moon sets), so that’s when you’ll want to step outside to scan for shooting stars until dawn.

Around 4 A.M. local time, the radiant is some 65° high in the west. It’s located just northwest of the bright star Castor. The best strategy to catch shower meteors is actually a to look a bit away from the radiant. That’s because meteors originate at the radiant, so their trails will streak away from this point. The Geminids are expected to produce up to 150 meteors per hour at their peak, so you should expect to see several shooting stars the longer you stay outside, with numbers diminishing as dawn approaches and lightens the sky. If possible, pick an observing site well away from any light pollution, bundle up (for those in colder climates), and avoid using a telescope, as its small field of view will limit or eliminate any streaks you might see. Instead, scan the sky with your eyes or binoculars to catch the most meteors.

Sunrise: 7:14 A.M.
Sunset: 4:35 P.M.
Moonrise: 2:05 P.M.
Moonset: 2:54 A.M.
Moon Phase: Waxing gibbous (83%)

Wednesday, December 15

The Moon passes 1.5° south of Uranus at 1 A.M. EST. At that time, the pair is relatively high in the west, located in the southern portion of Aries the Ram. Our Moon is a waxing gibbous some 87 percent lit, while the distant ice giant Uranus shines at magnitude 5.7. That makes it easy to capture with binoculars or a telescope, although the bright moonlight may increase the challenge a bit.

Once you’ve found the planet, you may notice that its small, 4″-wide disk is colored grayish-blue. The planet’s cloud tops typically show no detail, so it should appear uniform in color. Uranus is well known for its odd — and extreme — tilt, which is nearly 98° and essentially places the planet on its side. This means its ring system (unfortunately invisible in your scope) is also tilted, circling the planet face-on from our point of view.

Sunrise: 7:15 A.M.
Sunset: 4:36 P.M.
Moonrise: 4:30 P.M.
Moonset: 3:54 A.M.
Moon Phase: Waxing gibbous (90%)

Thursday December 16

Venus has become an unmistakable beacon in the evening sky, seated in northeastern Sagittarius and setting some two hours after the Sun. Nearby, just one constellation over in Capricornus, is Saturn, glowing a much more muted magnitude 0.6 to Venus’ spectacular magnitude –4.9. The two began the month 18° apart and have been creeping closer over the past two weeks. Tonight, they reach their closest approach, separated by 14°. Once you’ve found Venus, simply scan east on the sky, along the ecliptic, to find dimmer Saturn. Beyond it, now having passed into Aquarius, is Jupiter, now magnitude –2.2.

Take some time to enjoy these planets through a telescope. Venus is the smallest of the three but also the closest to Earth. It presents a disk that is just 15 percent illuminated but spans 50″ on the sky. Its phase will continue to diminish but its size grow for the rest of the month. Saturn, the farthest of the three and middling in physical size, appears 16″ wide, flanked by its fantastic rings, which stretch 35″ end to end. Now is the time to view this planet with a telescope, as it will continue sinking toward the horizon in the coming weeks. Finally, the largest planet in the solar system, Jupiter, appears 37″ across and is flanked by all four of its Galilean moons this evening. Europa lies alone to the planet’s east, while, stretching from closest to farthest, are Io, Ganymede, and Callisto to the west.

Sunrise: 7:16 A.M.
Sunset: 4:36 P.M.
Moonrise: 2:58 P.M.
Moonset: 4:55 A.M.
Moon Phase: Waxing gibbous (95%)