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Feature Article - September 29, 2005

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September 29, 2005

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Gray MerriamLegaleseGeneral information and opinion on legal topics by Rural Legal ServicesNature Reflectionsby Jean GriffinNight Skiesby Leo Enright

Mars, the feature attraction of October

by Leo Enright

At the beginning of October, sunset in this area is at about 6:45 p.m. Eastern Daylight Time, and astronomical twilight ends at about 8:30 p.m., more than an hour earlier than it did a month ago. By the end of October sunset will be a few minutes before 6 p.m. with astronomical twilight lasting until a few minutes after 7:30 p.m. However, on October 30, at 2 a.m., our clocks will be returned to Standard Time, and so, that night, the eve of Halloween, and the next night, Halloween, the ‘Eve of All Hallows’, will seem to be even longer, with sunset being before 5 p.m., and the end of astronomical twilight occurring just after 6:30 p.m. Standard Time.


These increasing hours of darkness mean more people can enjoy the wonders of the autumn sky, which still features the Milky Way passing overhead, in a grand northeast-to-southwestern sweep in the early night, and in an east-to-westward direction in the late night. This enormous band of light, which we are so fortunate to be able to see from our rural locations, is the starlight from the many millions of stars in our home galaxy, our sun being just one of those many millions. Skywatchers who have observed the Milky Way over the past few months know by now three of the constellations that are found within it: Cassiopeia, in the shape of a large “W” now high in the northeast; Cygnus, the Swan, also known as the Northern Cross, which is now slightly west of the directly overhead position it occupied last month; and Aquila, the Eagle, which is now in the southwest. Low in the south, where the “Teapot of Sagittarius” was seen last month, we now find the constellation Capricornus, the Sea-goat, or Goat-fish, a bizarre creature from ancient mythology. Modern stargazers tend rather to see the shape of an enclosed “V-shaped” pattern resembling the appearance of the hull of a boat viewed from the front. Sagittarius’s Teapot has moved low into the southwestern sky and starts setting soon after midnight. The three very bright stars of the Summer Triangle may be no longer straight overhead in the evening, but, except for planets, they dominate the western half of the sky until they start to set after 3 a.m. Meanwhile in the late evening, the brightest of what we call “the winter stars” are moving up into the eastern and southern skies, led by the famous cluster of stars called The Pleiades, sometimes called “the Seven Sisters”, and in Japan known as “Subaru” (an image easily recognized in the logo of a well-known car maker). This “little cloud of stars” can be seen in the east any time after 10 p.m. On clear, moonless nights, test your eyesight. If your location is not too light-polluted, you should be able to distinguish the cluster’s six brightest stars. Then note whether you are able to see the “Seventh Sister” or the “Lost Pleiad.” (Sharp visual acuity may allow you to do so. Many children can do this more easily than adults.) Then with a pair of ordinary binoculars, marvel at the brightest two dozen stars in the cluster, and if conditions are very good, at the slightly bluish nebulosity that may be seen near one of the stars near the centre of the cluster. By midnight, the outline of Orion, the Great Hunter may be seen rising in the southeast – a forecaster of the many brilliant stars to be enjoyed over the winter months. Among the bright planets, only three of the five are easily seen this October, but one of them makes a truly spectacular appearance. Jupiter and Mercury are the planets that will probably be seen by extremely few people because of their position in the sky. Both are very low in the west for a very short period of time after sunset, and Jupiter only for a few days at the beginning of the month, and Mercury only near the end of the month. How different are the prospects for the other three planets! Brilliant Venus, the brightest planet of all, can be easily found after sunset low in the southwestern sky, if one has a good view in that direction, and it can be observed for almost two hours until it sets. Beside Venus on the evening of October 16, try to see the star Antares, brightest star in the constellation Scorpius, less than 2 degrees to the lower left of Venus. (That is less than the width of 2 fingers held at arm’s length.) Mars is spectacular and dramatic this month, much brighter than it usually appears. In fact, it will appear brighter to the eye, and larger in a telescope, than at any time in the next 13 years. In late October and in early November this year, Mars will reach the two points called “closest approach to Earth” and “opposition”, events that happen once every 26 months, when Earth and Mars are in the same direction as “viewed” from the Sun. Though these events happen once every 26 months, we are fortunate that the approaches of these two planets in 2003 and in 2005 are slightly closer than usual, giving a slightly enhanced brightness on these two occasions. (However, anyone who has heard of the recent fraudulent chain-letter on the Internet, with its ridiculous claim that Mars would become as bright as the Full Moon, can rest assured that all such statements in that letter were utter nonsense!) Mars, with its distinctive reddish-orange colour is easily seen in the eastern sky after 9 p.m. in early October and much earlier than that in late October. Each time “closest approach” and “opposition” of Mars occur, the planet, for a 2 month period, may be seen moving backwards in the sky against the background stars, an event known as its “retrograde motion.” Try to note its position very carefully among the stars, and see if you notice that, instead of going slightly eastward, as usually happens, it actually moves westward between October 1 and December 10 of this year. Then, its eastward movement will resume among the stars of Aries and Taurus. Saturn, considerably fainter than Mars, this month rises in the east-northeast at about 2 a.m. in early October, but much earlier, even by midnight in late October.

Even though we are again into the “eclipse season” with a solar and lunar event this month, local residents are quite unlikely to see either. The solar eclipse of October 3 is visible from Europe and Africa. The partial lunar eclipse of October 17 begins that morning at about the time the moon sets locally, with residents of Western Canada having a front-row seat. However, we can hope to see the Moon adding to some planetary views this month. Don’t miss the view low in the southwestern sky on October 6 from 30 to 60 minutes after sunset as the crescent moon appears just below Venus, and the following night, at the same time, when the crescent is to the left of Venus and below the star Antares. In the eastern sky on October 18 the almost Full Moon appears just above Mars, and the next night it is to the left of Mars and just to the right of the Pleiades. In the morning sky on October 25, the moon appears above Saturn and the following morning it is just below Saturn.

For those who are interested in having star maps and up-to-date information about observing the autumn sky, a book called The Beginner’s Observing Guide is now available at Sharbot Lake Pharmacy.

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