A comet for the holidays

Glenn K.
Glenn K. Roberts
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Although the final verdict on Comet ISON is not yet in, ground- and space-based telescopes indicate that the comet fragmented, and the greater part of it vapourized, as it swung close to the sun on Nov. 28.

The latest report is that some small part of the comet’s nucleus did actually survive the comet’s passage through the sun’s corona, but that it is not likely big enough to present a naked-eye comet throughout December. Using binoculars or a scope, start watching for Comet ISON, such as it will be, to the left of Saturn (about two fist’s width at arm’s length) in the eastern, pre-dawn sky about 90 minutes before sunrise on Dec. 10. On successive mornings, ISON will move higher and higher (to the left) in the darker, pre-dawn sky. Around the time of the winter solstice (Dec. 21), ISON will also become an evening object and will be visible all night long by the end of the month.

However, another comet, Comet Lovejoy (C/2013 R1), is now the object to watch throughout December. Lovejoy has been visible to the naked eye in the late night and morning skies since Nov. 1 and made its closest approach to Earth on Nov. 19 at a distance of nearly 59 million kms. Now, as it continues on its perihelion rendezvous with the sun on Dec. 25, it is expected to brighten further.

How it will perform when it appears on the other side of the sun in the latter part of the month is anyone’s guess, but it is expected to survive the trip and continue as a naked-eye object, hopefully with a spectacular tail. It is already a splendid view in binoculars and telescopes, and in quality photographs it displays a distinctly green coma around the nucleus and sports a bright tail.

Having passed near the bottom of the handle of the Big Dipper in late November, Lovejoy is now dropping towards the NE horizon during the pre-dawn hours. It will pass between the Big Dipper’s handle and the star Arcturus (in the constellation Bootes — the Herdsman), on its way towards the constellation of Hercules — the Giant at year’s end. To spot Comet Lovejoy, first find the Big Dipper in the NE sky, then follow “the arc” of the Dipper’s handle to the bright, orange star, Arcturus. Sweep the area between the handle and Arcturus, dropping lower towards the horizon with each sweep. Lovejoy should be readily visible. Consult either www.astronomy.com or www.skyandtelescope.com for detailed sky charts showing Lovejoy’s (and ISON’s) current position.

Venus, the “evening star,” shines bright in the west at dusk, and will be at its brightest (mag. -4.9) on Dec. 6. Point of interest: Venus is the only planet capable of casting a shadow; try it on Dec. 6. Unfortunately, the brilliance of Venus in the evening sky will be somewhat diminished by the waxing, crescent moon lurking nearby. This evening (Dec. 5), look for the waxing, crescent moon to the upper right of bright Venus in the SW. Venus sets about three hours after the sun in early December and approximately 90 minutes after the sun by month’s end. By then, it will have faded significantly in brightness. Venus remains in the evening sky throughout December, becoming a morning object in January.

Saturn rises about two hours before the sun in early December and about four hours before sunrise by month’s end. On the mornings of Dec. 28 and 29, the waning, crescent moon slides from Saturn’s upper right to its lower left. You’ll need at least a small telescope to have a chance this month at viewing Saturn’s magnificent ring system, which is tilted more than 21 degrees (from edge on) towards Earth, showing the system’s north face. The best chance will be towards the end of the month, when Saturn, having risen a few hours before sunrise, will be much higher in the eastern, pre-dawn sky.

Mercury will be visible just before sunrise in the early December low on the eastern horizon. Mercury will become an evening sky object in late December, but will not become visible here in the evening twilight until the latter half of January 2014.

As December opens, Jupiter becomes visible in the east during the early-to-mid evening hours (7-8 p.m.), and shines, brilliantly all night. By month’s end, it is up by dusk or nightfall (approximately 6 p.m.).

The moon (just passed full) swings by Jupiter on the evenings of Dec. 18 and 19. Jupiter will replace Venus as the bright beacon of the evening sky in January 2014.

Rising around 1 a.m. this month, Mars should be easy to spot before sunrise, as it climbs higher into the eastern predawn sky and brightens throughout the month. It reaches its highest point in the sky around 7 a.m. in early December and by about 6 a.m. near the end of the month. Look for Mars to the lower left of the waning Moon between midnight and dawn on the mornings of Dec. 25 and 26.

The Winter Solstice, the official commencement of winter, and the longest night of the year here in the Northern Hemisphere, occurs this year on Dec. 21st at 1:11 p.m.

This year, the Geminid meteor shower (radiant in the constellation of Gemini - the Twins) has two peaks, the nights of Dec. 12-13 and Dec. 13-4. Of the two, perhaps the best will be the night of Dec. 12-13, as the waxing, gibbous moon sets earlier that night than it does the following night. Whichever night you choose, the greater number of meteors is likely to come in the hours after the moon sets and dawn, so dress warmly. The Geminid meteor shower often rates as one of the best, if not the best, shower of the year, especially on a dark, moonless night. Under a dark sky, expect to see up to 50-plus bright meteors crossing the sky from the west.

Finally, December’s full moon on Dec. 17 was often referred to as the “long night moon” by North America’s native peoples, as this was the month of the winter solstice and the longest night of the year. Early settlers called it the “yule moon” in honour of the yuletime festivities of December.

Until next month, clear skies and happy holidays.


Events (AST):

Dec. 9 — First quarter moon; 11:12 a.m.

Dec. 12-14 — Geminid meteor shower peaks, best during pre-dawn hours

Dec. 17 — Full moon; 5:28 a.m.

Dec. 19 — Moon at apogee (furthest from Earth); 403,910 kms; 7:48 p.m.

Dec. 21 — Winter solstice; 1:11 p.m.

Dec. 25 — Last quarter moon; 9:48 a.m.


Glenn K. Roberts is a member of the Charlottetown Centre of the Royal Astronomical Society of Canada (RASC). His column appears in The Guardian once a month. He welcomes comments from readers. Anyone who would like to comment on his column is encouraged to email him at glennkroberts@gmail.com.

Organizations: Royal Astronomical Society of Canada, Twins, Charlottetown Centre

Geographic location: North America

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