This Week’s Sky: December 15 – 22

Winter arrives with a new Moon.

All Week

Southwest, 1 hour after sunset.

The view facing southwest, one hour after sunset.

If you look very low in the western sky just after sunset you might catch a glimpse of Venus, now beginning an evening apparition. It sets just 50 minutes after the Sun, so it’ll be tough to fish the planet out from bright twilight low in the west. The situation will gradually improve in the coming weeks though. Mars is continuing its climb north and east along the ecliptic through Capricornus. The red planet hangs 20 degrees above the southwest horizon one hour after sundown, and sets shortly after 8 p.m., local standard time. Jupiter is the best planet to observe with a telescope at the moment. Big Jove rises a little after 11 p.m. and is at its best at 4 a.m., when it transits the meridian. Last to join the planet parade is Saturn. The ringed wonder rises at 5:30 a.m., more than two hours ahead of the Sun. It’ll be a while though before Saturn climbs high enough to be a rewarding telescopic target.

December 16

Double-shadow-transit

The double-shadow transit is shown for 1:42 a.m., EST.

This morning there is a double-shadow transit on Jupiter, viewable across the country. Observers on the East Coast enjoy the most favourable conditions. but even from Ontario, Jupiter will have an altitude of 41 degrees at 1:12 a.m., EST (10:12 p.m., PST, December 15), when Io’s shadow joins Europa’s on the planet’s disc. The double-shadow transit concludes at 2:02 a.m., EST, as Europa’s shadow drifts off Jupiter’s western limb. What makes this event especially interesting is that Europa itself will closely follow Io’s shadow across the planet — see if you can spot it.

December 19

Moon and Saturn

The Moon and Saturn as viewed in 10×50 binoculars.

This morning the thin waning crescent Moon will have a close encounter with Saturn. For viewers in Eastern Canada, the pair will be a little more than four degrees apart. On the West Coast, they will be less than three degrees aprat when they rise. The conjunction will be a fine naked-eye sight and enjoyable in binoculars too.

December 21

Winter solstice

During the winter soltice, the Sun is in the constellation Sagittarius and at its southernmost point on the ecliptic.

Today marks the winter solstice — the shortest day and longest night of the year. This is when the Sun reaches its most southern point on the celestial sphere. Winter officially begins at 6:03 p.m. EST. From this point on, the days gradually begin to get longer and the nights shorter. Depending on your preferences, that’s either cause for celebration or dismay.

At 8:36 p.m., EST, only a couple hours after the winter solstice, the Moon is new. A new Moon on the longest night of the year is surely a deep-sky observer’s dream come true.

December 22

If you have an unobstructed southwest horizon (and only then) you might catch Venus and a razor thin crescent Moon close together just after sunset. For viewers on the East Coast, the Moon will be less than 24-hours old, and only one percent lit. You’ll need binoculars, and it’s likely you’ll spot Venus first. If you do, look for the Moon about six degrees to the right of the planet.

Weekend Stargazer

Weekend sky tour

The evening sky features some of the season’s best and brightest deep-sky sights. (Click on image for a full-size version.)

The December 19 – 21 weekend features the longest night of the year and a new Moon. For deep-sky observers, that calls for some serious telescope time. Indeed, there’s so much darkness available on long winter nights that it can be difficult to decide what to look at first. Given the scarcity of clear nights at this time of year though, it’s not a bad idea to check in on some favourites before digging into more challenging fare.

An evening sky tour this weekend will allow you to take in quite a few of the best and brightest deep-sky objects in the entire sky. Start off with the Andromeda Galaxy (M31) — arguably the finest galaxy visible. It’s an easy binocular find and magnificent in a low-power telescope. Next, take in the Double Cluster in Perseus. Like M31, this is a great binocular sight and lovely in a small scope. For an even better cluster, zip down to the Pleiades (M45) in Taurus. For my money, this collection of bright stars is one of the very best binocular objects available, north or south. Next stop: the Orion Nebula, M42. This glowing cloud of gas is splendid in any instrument from binoculars up to a monster Dobsonian. After inspecting M42 at low power, add moderate magnification to enjoy the four stars in the centre of the nebula that make up the Trapezium. Last, but not least, low in the southeast is Sirius, the brightest star in the night sky. Thanks to the prismatic effects of Earth’s atmosphere, the star can flash different colours when it’s rising. It’s just an optical illusion, but striking none the less.

At SkyNews we love to read about your experiences and see your photos. You can share them with us by e-mailing dickinsonSkyNews@gmail.com.

Categories: This Week's Sky

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