| Sep 27, 2007


Feature Article - September 27, 2007

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Night Skies - September 20, 2007

Spectacular Morning Conjunction & Two October Meteor Showers

by Leo Enright

Locally, at the beginning of October, sunset is at about 6:45pm EDT and astronomical twilight ends at about 8:30pm. By the end of October sunset will be a few minutes before 6pm with astronomical twilight lasting until a few minutes after 7:30pm. The Milky Way that featured so prominently in the summer evening sky still sweeps overhead in a northeast-to-southwest direction in the early night, and in an east-to-west direction later in the night. This great band of light, which we are so fortunate to be able to see from our rural locations, is actually the combined starlight from the many billions of stars in our home galaxy, the Milky Way Galaxy.

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As the night advances, we see the constellations within the Milky Way and west of it, the ones sometimes called ‘the stars of summer’, setting in the west and northwest. The constellations east of it, the ones sometimes called ‘the stars of autumn’ are seen in the south-eastern sky. In this way the great Milky Way serves as ‘a divide in the sky’. In the later evening when we see the famous Pleiades Star Cluster (also called The Seven Sisters) rising in the east, we know we are now starting to look at the ‘stars of winter’, and shortly we will see Taurus, The Bull, and Orion, The Hunter, moving up into view over the south-eastern horizon. These are the bright ‘winter stars’, as always, arriving on schedule.

Of the five bright, naked-eye planets, four may be very easily seen this month, and one only briefly and with difficulty. Mercury is the difficult one, since it may be seen only in the first week of the month and very low in the west for a brief while, about an hour after sunset. Jupiter continues to dominate the south-western sky beginning shortly after sunset, but its period of dominance decreases, and by the end of October, it sets within an hour of our first sighting it. It will be seen in the evening twilight slightly above the reddish star Antares, brightest star in the constellation Scorpius. Very careful observers may note that Jupiter dims slightly over the course of the month, and if binoculars are used, its orbital movement to the left among the stars may also be detected. Mars is the dramatic planet this month. This obviously reddish-orange object is becoming much brighter than it was in the last two months. It rises in the east at about 11pm at the beginning of October, and earlier each evening until by month’s end, it may be seen at about 9:30pm or shortly thereafter. Using binoculars to follow its orbital motion eastward among the stars would be an interesting suggested project, especially every night in the first week of the month when it passes very close to a bright star in the constellation Gemini and later a large cluster of stars known to astronomers as M35. The brilliant object dominating the morning sky (No, it’s not a UFO!) is the planet Venus, now bright enough to be seen in the daytime – well worth the effort of setting the alarm for 4:30am! Unlike Jupiter in the evening, the period of its dominance in the morning sky increases over the month until by the end of October, Venus rises about four hours before the sun, and is the unmistakable centre of attraction in the eastern sky. Watching its changing phases (like those of the moon) and its orbital movement among the stars with binoculars or a small telescope is certainly worth the early-morning effort this month. The movement of Venus is almost as dramatic as its brightness this month, and watching its movement among the stars allows us to identify the last of the bright planets to be seen this month, Saturn. In the first four days of the month Venus appears above, and to the right of, Saturn with the star Regulus almost mid-way between them. In the next three days Venus appears to move downward to the right of Regulus, and then from October 12 to 15, Venus is to the right of Saturn. For the remainder of the month, Venus gradually moves further downward in the sky appearing, morning by morning, further below the planet Saturn. The close trio of Venus, Saturn, and the star Regulus is made more spectacular on three October mornings, the 6th, 7th, and 8th. On the 6th, the crescent moon appears just above the heavenly trio. On the next morning, October 7, the slim crescent moon appears right within the trio. (Don’t forget to set the alarm for 4:30am that morning!) As you stand in awe, with open mouth, looking at this spectacle, think of the time it has taken the light to get to your eyeballs from those four objects: from the crescent moon – 1 second; from Venus – 4 minutes; from Saturn – 1 hour; and from Regulus – 78 years! On October 8, the very slim crescent moon appears well below the trio. Some people may want the challenge of seeing the moon again the following morning, the 9th, but binoculars will likely be needed and a very good view right down to the horizon, 60 to 45 minutes before sunrise.

Three additional events warrant our attention: On October 9 the Draconid Meteor Shower reaches his peak. On that night and also the previous and following nights, there may be numerous “shooting stars” in the northern part of the sky. Observers may watch at any time during the night. The even more famous shower, the Orionid Meteor Shower peaks on October 21. Observers may see numerous meteors in the last half of the night during the three days before and after the actual peak, as well as the night of the actual peak, with meteors probably more frequent in the south-eastern part of the sky. On Saturday night, October 27, the rising moon, just past Full Moon, will occult some of the stars of the Pleiades Star Cluster (the famous Seven Sisters). That means some of its stars will be hidden as the moon moves in front of them. I suggest using binoculars to assist in seeing which of the stars are occulted and to see them again pop into view at the edge of the moon after being occulted. It is an interesting phenomenon, especially if one has not seen a lunar occultation before.

More information about observing the night sky is readily available in the book The Beginner’s Observing Guide now available at Sharbot Lake Pharmacy.

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