December 2011

Planets Grace the Sky all Night Long

The month of December has the longest nights and shortest periods of daylight than any other month of the year in the northern hemisphere. This means that stargazers have plenty of time to observe the stars and planets of the night sky before retiring to bed and before the light of dawn begins to intrude into the darkness of the heavens.

With this extended period of darkness we have the opportunity to see the bright planets throughout the nights of December.

At the beginning of December the planet Venus can be seen about 30 minutes after sunset low above the southwestern horizon. Its brilliant white glow of magnitude -3.9 makes it rather easy to spot in the fading light of dusk. It will appear higher each week after sundown on its way to a spectacular pairing with Jupiter in March of next year. In the telescope it displays a rather small bland waning gibbous disk.

In the darkening skies after the sun has set Jupiter appears well up above the southeastern horizon throughout the month of December. Its bright yellowish colour shines at a magnitude of -2.7 making it easy to find amongst the faint background stars. Jupiter resides at the boundary of the constellations of Pisces and Aries throughout the month. Even though Jupiter was at opposition (closest to Earth) at the end of October it still presents an excellent telescopic target. The dark atmospheric bands are easily seen in small telescopes as are the four largest satellites of this giant planet.

Mars rises just after midnight at the beginning of December. Observers will notice the Red Planet grow prominently in brightness from magnitude 0.8 at the beginning of December to magnitude 0.2 by the end of the month, an increase of nearly 75 percent. Its reddish-orange glow is easily spotted amongst the fainter background stars in the constellation of southern Leo. Mars is still too distant to show any surface details in smaller telescopes. This will change as Mars approaches opposition at the beginning of March of next year.

Saturn can be seen rising around 2:30 a.m. above the eastern horizon at the beginning of December in the constellation of Virgo. The Ringed Planet’s yellowish radiance (magnitude 0.7) is slightly brighter than Virgo’s brightest star blue-white Spica shining at magnitude 1.0. Saturn resides within 5 degrees of Spica throughout December.

One of the strongest annual meteor showers, the Geminids, peak the night of December 13/14. Unfortunately the moon will be in a waning gibbous phase and its brightness in the night sky will wash out all but the brightest meteors of the shower.

The waxing gibbous moon can be found about five degrees above and to the left of Jupiter after sunset on December 6. Before sunrise the last quarter moon can be seen below and to the right of Mars on December 17. Before the night sky lightens on December 20 the waning crescent moon will be located directly below the planet Saturn. After sunset on December 27 the thin waxing crescent moon will be hanging just above Venus.

A total eclipse of the moon will occur on December 10. Unfortunately for us we will be unable to see the moon enter the Earth’s shadow as it will have set by that time. Only those who live west of the province of Manitoba will witness totality when the full moon becomes immersed entirely in the Earth’s dark inner shadow. We must wait until April 15, 2014 before Thunder Bay will witness a total eclipse of the moon.

December hosts the winter solstice. This is the time of year when the season of winter begins for us in the northern hemisphere. South of the equator the seasons are reversed so they will be looking forward to the beginning of summer. Officially winter begins on December 22 at 00:30 a.m. (30 minutes after midnight) EST. This point in time marks the winter solstice for us and the summer solstice for those residing in the southern hemisphere.

Clear Skies

Ted Bronson