Mars grabs summer's celestial centre stage

COFFEE WITH WARREN, with Warren Harbeck
Cochrane Eagle, July 9, 2003

Mars will be the closest to Earth it has ever been in recorded history this summer.

In view of the significance of this event, I have asked our stargazer coffee companion Bruce McCurdy to provide a rundown on the summertime celestial show.

Bruce, a past president of the Royal Astronomical Society of Canada Edmonton Centre, is education development coordinator of the Sky Scan Awareness Project, a not-for-profit resource to the Grade 9 Alberta science curriculum. A frequent contributor to this column, he also contributes to popular astronomy magazines. His technical articles on this summer's Mars events have appeared in recent editions of the Journal of the RASC.

Bruce writes:

QUIETLY, the God of War is sneaking up behind us. The planet Mars is ready to invade, soon to cross the borders of our consciousness with its closest, brightest display in our lifetimes.

Mars will start rising before midnight in mid-July, but it takes its time clearing the horizon. Look low in the southeast for a reddish object visibly larger and steadier than a star. Not to mention brighter. Mars is doubling in brightness during July, and will redouble in brightness in August, all the while rising some three to four minutes earlier per night.

By the morning hours of Aug. 27, the Red Planet will be at its closest to Earth in human history. At magnitude minus-2.9, it will briefly outshine mighty Jupiter at its brightest. Only our closest neighbor Venus achieves greater lustre than Mars will this summer, but she is absent from the midnight sky.

Mars is the only planet to display significant surface features. Venus and the gas giants Jupiter, Saturn, Uranus and Neptune have opaque atmospheres, while tiny Mercury presents insuperable challenges due to lack of contrast in the Sun's glare.

Over 55 million km away at its nearest, Mars is about 150 times the average distance of the Moon. A good telescope operating at 150 power will reveal detail on the scale that one can resolve on the Moon with the unaided eye. But these subtle details include its famous reddish hue, light and dark regions, polar ice caps, and perhaps the shifting sands of a planet-encircling dust storm.

Alas, the geometry of a close Mars approach does not favor observers in the northern hemisphere. Mars will remain low in the southern sky throughout the weeks of closest approach, leaving a limited window for observation and, worse, an unfavorable angle at which to point your telescope through Earth's obscuring (albeit necessary) atmosphere. It will nonetheless be well worth the effort to do so to get a glimpse of our angry neighbor at his most forbidding. If you don't have access to a scope, look up your local observatory (Edmonton's Odyssium and the Calgary Science Centre, to name a couple), or cozy up to a friend who enjoys astronomy.

Much can be discerned with the unaided eye – or better yet, a pair of binoculars – as Mars whips by at an unusually fast speed. Ironically, the brighter the Red Planet gets the whiter it appears, its ochre hue bleached out like an overexposed photograph.

As planets go, Mars has a significantly eccentric, egg-shaped orbit, and happens to make its closest approach to the Sun on August 30, just as Earth on its inside track passes by. This favorable alignment, combined with the fact that Mars' eccentricity is gradually increasing at present, makes this its closest approach to the Blue Planet, Earth, in some 73,000 years.

—Bruce McCurdy, Edmonton

TO SUMMARIZE: except for the Moon, Mars will be the brightest object in the midnight sky this July and August. (This does not apply, of course, to readers north of the Arctic Circle, in the land of the midnight sun.)

By mid-August, Mars will be clearly visible in the southeast by 10 p.m. and will remain visible in its westward journey till overtaken by dawn.

Next week, we'll consider how the macho planet will stand atop Earth's Moon during the night of July 16/17 as it prepares to dance backward for a while across the starry sky.

© 2003 Warren Harbeck

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