A bright comet heralds arrival of spring

Glenn K.
Glenn K. Roberts
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The vernal equinox, or the official start of spring, occurs on March 20 this year at 8:02 a.m.

Only Jupiter and Saturn are readily visible in the night sky this month. Jupiter sits in the constellation of Taurus - the Bull this month and is visible in the early evening sky, well above the western horizon as twilight falls.

On March 17, the crescent moon sits just south of, and very close to, Jupiter (a nice photo op). Saturn rises before midnight all month long and is prominent in the SE sky. On March 29, the waning, gibbous moon sits just below Saturn, whose magnificent ring system is readily visible through a good pair of binoculars or a scope this month.

Of course, the big excitement in astronomy circles this month is the arrival of Comet PanSTARRS, the brightest comet in the past six years, into the evening skies of the northern hemisphere. This comet, officially known as Comet C/2011 L4, was discovered in June 2011 by astronomers using the Panoramic Survey Telescope and Rapid Response System telescope (thus the name PanSTARRS) in Hawaii.

Astronomers, both amateur and professional, and the general public in the southern hemisphere have had an almost exclusive look at the approaching comet over the past few weeks. Though off to a slow start in turns of anticipated brightness, reports now indicate that PanSTARRS has dramatically brightened over the past two weeks, and is rapidly approaching the level of brightness expected of it.

It now looks like it will be a naked-eye object (0 mag, and possibly -1 mag) by the time it becomes visible in the evening sky this month.

It made its closest approach to Earth (perigee) on March 5 and will reach perihelion (its closest approach to the sun) on March 10.

PanSTARRS is a virgin comet, meaning that this is its first visit through our solar system. And, as with all virgin comets, no one is exactly sure how it will perform — it could be a dud and fail to put on much of a show (as has happened with comets in the past) or it could burst forth in a radiant display with a magnificent tail(s) after perihelion. Let’s hope it is the latter.

Start looking for the comet low above the western horizon this evening about a half hour after the sun sets. Don’t be discouraged if you don’t spot it easily; it will, after all, be very low above the horizon against a still-bright sky.

March 12 should (if the weather gods co-operate) afford a better opportunity to spot PanSTARRS as you will have the moon to help you. On the evening of March 12, look for the thin, crescent moon just above the western horizon about a half hour after sunset. Look for a wispy “V” shape just to the left of the Moon, with the comet’s head (coma) in line with the moon.

Hopefully, by then, PanSTARRS will be a naked-eye object with a spectacular tail. The comet’s tail (if, indeed, one develops) will initially point straight upward, with a slight lean to the left, but as the month progresses will shift to the right. An unobstructed western horizon (over water would be perfect) will present the best opportunity to see the comet.

If the comet does not readily jump out at you, use a good pair of binoculars to sweep the area to the left of the moon, as you will only have about an hour to view the comet before it disappears below the horizon.

On the evening of March 13, the comet’s tail should be in line with the moon.

Comet PanSTARRS will continue to slowly get higher in the evening sky each evening and shift slowly toward the west-northwest part of the sky during the middle and later part of March, and into April. Though we will be able to find the comet more readily in the night sky as March progresses, due to its increased height on successive nights, moonlight after March 12 will diminish the view somewhat. Also, PanSTARRS will grow dimmer as it slowly moves away from the sun and Earth and back into deep space.

Join me at Indigo Bookstore on University Avenue in Charlottetown on Monday, March 11, 2-4 p.m., when I will be on hand to talk about where to look for Comet PanSTARRS throughout March and April. I will be joined by well-known Charlottetown photographer Clair Perry, who will provide information on how to take pictures of the comet with your digital or SLR camera. Both he and I will be back in the Indigo Bookstore in November to make a similar public presentation on Comet ISON, anticipated to be “the comet of the century.” Drop in, come over to say hello and ask questions about Comet PanSTARRS or any other celestial object. We hope to see you there.

Until next month, clear skies and good comet hunting.


Events (ADT):

March 10 — Comet PanSTARRS at perihelion; 44.8 million kms.

March 11 — New moon, 4:51 p.m.

March 12 — Comet PanSTARRS visible to left of crescent moon in the west half an hour after sunset

March 19 — Moon at apogee (farthest from Earth); 401,191 kms, 12:13 a.m.; first quarter moon; 2:27 p.m.

March 20 — Vernal equinox (start of spring); 8:02 a.m.

March 27 — Full moon; 6:27 a.m.

March 31 — Moon at perigee (closest to earth); 365,369 kms.; 2:51 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: Panoramic Survey Telescope and Rapid Response System, Indigo Bookstore, Royal Astronomical Society of Canada Charlottetown Centre

Geographic location: Taurus, Hawaii.Astronomers, Charlottetown

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