Feature Article April 10, 2002
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A truly rare evening gathering of planetsby Leo EnrightWith the change to Daylight Saving Time on the first Sunday of the month, the rapid increase in the hours of daylight seems more dramatic than it actually is. At the beginning of April, sunset in this area is at about 7:30 p.m. EDT, and by the end of the month it occurs a little after 8 p.m. EDT. The end of evening twilight changes from 9:15 p.m. EDT to about 10 p.m. at months end. Sunrise times move from 6:50 a.m. at the first of the month to 6 a.m. on the last day of April.During evening twilight, skywatchers can see the winter star patterns sinking low in the western sky and the large spring constellations moving upward into the eastern and southern parts of the sky. High in the south, the outline of Leo, the Lion, is seen with its large backwards question mark forming his head and forepaws, and with the brilliant star Regulus marking one front paw. Somewhat to his left and down into the southeastern sky stretches Virgo, the Maiden, marked by the very bright star called Spica. Further to her left and down near the southeastern horizon is the box-like pattern of four stars known as Libra, the Scales. Within the regions of these three large constellations, observers who have binoculars and telescopes can spend hours finding and studying very distant galaxies and also many interesting variable stars within our own galaxy. For observers who watch the skys wonders with the unaided eye, this will be a truly remarkable month, since all five of the bright planets of our solar system will be more closely arrayed in the evening twilight than they have been at any time since the month of February 1940. Yes, over 62 years ago! As for the future, for Canadian observers who miss this grouping of bright planets, they will not see a similar one until the array in the morning sky in July 2060, and in the evening sky in January 2081! Truly the gathering of the planets in the evening sky this month will be a once-in-a-century event. Jupiter, our solar systems largest planet, is seen early in twilight very high in the western sky. Downward from it a pair of bright stars will appear. The reddish-orange one on the left is the star Aldebaran, the Eye-of-the-bull star in the constellation Taurus, and the creamy yellow one on the right is not a star, but Saturn, second largest planet of our solar system. Further down and to the right, reddish Mars is seen as evening twilight darkens. Still closer to the horizon is Venus, absolutely unmistakable because of its great brilliance. Beginning on April 15, the fifth bright planet, Mercury, may be seen very low and close to the western horizon for a short while beginning about 40 minutes after sunset. The planetary arrangement will change slightly as the month passes. From night to night, Saturn will appear to move upward and closer to Jupiter. Mars will appear to move upward and closer to Saturn. Venus will move upward toward Mars. Finally in the last ten days of the month, Mercury will move upward toward Venus. The movement of the planets against the background stars will be easy to notice: Saturn moving upward and away from the Hyades cluster that forms the head of the Bull in Taurus, Mars climbing from the area of the Pleiades and up past the Hyades, and Venus climbing up past the Pleiades or the Seven Sisters star cluster, being particularly close to them on April 24, 25, and 26. (Try to record any of these night-to-night changes that you notice.) As the moon orbits the earth this month, it provides some very fascinating views in the evening twilight. Shortly after sunset on April 13, the extremely thin crescent will appear just to the left of Mercury, but this pair will be so close to the western horizon that most people will miss the sight. On the 14th, the slender crescent will be just to the left of Venus, and these two objects will provide a truly fabulous sight in the west after sunset! On the 15th, the crescent will be just to the left of Mars. On the 16th, it will be seen just above the planet Saturn, and on the 18th, it will be close to Jupiter. Try to see as many of these moon-planet conjunctions as possible, marking them on a calendar, if necessary, so as not to miss them. As usual, be sure to turn off outdoor lighting. There has been some very exciting news in recent weeks concerning the discovery of three comets - all of them visual discoveries (as opposed to photographic, or computerized camera, or spacecraft searches). One of them, Comet Ikeya-Zhang, named after the gentlemen in Japan and China who independently discovered it the same night, February 1, has brightened into a beautiful comet which I have observed six or seven times. Though it may be spotted with the unaided eye, binoculars are recommended in order to appreciate the long and bright tail that may be seen. Look low in the west-northwest about 45 minutes after sunset. Remember also to check the northern part of the sky for possible displays of the Aurora Borealis. For the 30th year, Astronomy Day is being celebrated in North America on Saturday, April 20. This countys major astronomy club will be holding a day-long display at Kingstons Frontenac Mall and an observing session at MacDonald Park. Everyone is invited to both events. All readers of this column are also advised of the upcoming adult interest course in astronomy offered at Perths Algonquin College during the month of May, one night a week - a relaxing way to learn about the basics of astronomy and about the spring and summer sky. For details, phone 267-2859 as soon as possible.
More information about observing the night sky may be obtained from the book, The Beginners Observing Guide, which is available from Sharbot Lake Pharmacy. Clear skies for good observing!
