Moon, planets to promenade across western sky

COFFEE WITH WARREN, with Warren Harbeck
Cochrane Eagle, April 10, 2002

"This type of show can be enjoyed by anybody with a pair of eyeballs and a brain."
— Bruce McCurdy

The stars are lining up! The stars are lining up! Well, sort of. And when interesting things happen in the night sky, I often call on e-mail coffee companion Bruce McCurdy to add clarity.

Bruce, education development coordinator of the recently-founded SkyScan Awareness Project, a grant-funded astronomy program run through the University of Alberta, writes:

IF YOU'VE BEEN WONDERING about the string of bright lights stretching across the evening sky toward the west these days, you're hardly alone. Over the next several weeks we will enjoy the best alignment of planets in a century. Not since 1940, or again until 2040, will all five naked-eye planets be so easily visible in a single glance.

Jupiter, Saturn, Mars, Venus, and Mercury have no accredited discoverer; they've been known since antiquity. Indeed, along with the Sun and Moon, they are responsible for the ancient tradition of naming the seven days of the week. Use your hard-won bilingual skills and the relationship becomes obvious: the French mardi, mercredi, jeudi, vendredi and the English Saturday, Sunday, Monday can be clearly associated with these seven celestial bodies.

Of course, "alignment" must not be taken too literally. At their closest, Mercury and Jupiter will be about 33 degrees apart, about a tenth of a circle. But considering that the five are normally scattered all around the Great Circle known as the ecliptic, each stepping to its own drummer, to see all five squeezed into the same narrow piece of the pie is extraordinary.

For them to be far enough to one side of the Sun to be all visible in a darkening sky is even more so, and the fact that they are doing so in spring evenings rather than, say, the early, early pre-dawn sky of July, is our particular blessing this time.

The wonderful thing is this can all be appreciated with the unaided eye, with a simple pair of binoculars a useful, although not completely indispensable, accessory to accentuate the closer groupings. This type of show can be enjoyed by anybody with a pair of eyeballs and a brain.

While Jupiter, Saturn, Mars and Venus have been slowly coming together for some months now (Jupiter is the very bright planet at the eastern upper left end of the string, Venus the very bright planet at the western lower right end), in mid-April, tiny and elusive Mercury makes its entrance stage-west below Venus.

Last to join the party and first to leave, Mercury will -- as always– be found fairly low in bright twilight, as a bright "star" where no star exists. It might be possible to catch it as early as Saturday, April 13, when the sliver of the new Moon passes to its left. A pair of binoculars and an unimpeded view of the WNW horizon will be a must. Timing is critical, as the Moon and Mercury set an hour or so after the Sun. The optimal window is a half hour or so after sunset.

The rest of the week will see the waxing Moon making progressively more visible visits to each of the planets as it moves across the sky from west to east: Venus on the evening of April 14, Mars on April 15, Saturn on April 16, and Jupiter on April 18.

In some ways the best night will be Wednesday, April 17, when the Moon will temporarily fill the gap between Saturn and Jupiter, and our six closest neighbours will stretch out like a glorious string of Christmas lights. Picture them as a dotted line showing the path of the Sun as it rises to the summer solstice.

Less obvious than the Moon's will be the more subtle motions of the planets, relative to both the background stars and each other. Four of them are planning an elaborate square dance in the coming weeks. I will offer both a description and an explanation over a future cup of Coffee with Warren.

—Bruce McCurdy, Edmonton

FOR A GRAPHIC PERSPECTIVE on the planetary alignment, Bruce recommends Alan Dyer's five-page article in this month's edition of SkyNews magazine.

© 2002 Warren Harbeck

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