In the month of September, sky watchers are usually delighted both to have longer nights than they had in July and August and to enjoy the night skies without the hazy conditions that usually follow the hot days of mid-summer.

Sunset locally on September 1 is at about 7:45 p.m. Eastern Daylight Time, and evening astronomical twilight ends at about 9:30 p.m., which is over an hour earlier than it did a month ago. During September the time of sunset will be about 2 minutes earlier each evening, until by the end of the month it is at about 6:45 p.m., with twilight lasting until about 8:30 p.m.. (From these numbers you can calculate the times of sunset and end of twilight for each day of the month.) There is also a change of over a half-hour in the times of dawn and sunrise. On September 1^st, morning astronomical twilight begins at about 4:45 a.m. and sunrise occurs at about 6:30 a.m. Over the entire month of September, there is more than an hour and a half decrease in the time of daylight and, of course, an equal increase in the time of darkness. The beautiful Milky Way that we learned to appreciate over the summer months still sweeps overhead in the late evening hours. As in the last two months, we should look for Cygnus, the Swan, also called The Northern Cross, “flying” almost directly overhead as evening twilight ends. This “bird of stars”, “flying south” along the Milky Way, appears amid the three bright stars of the Summer Triangle, and it may remind us of the coming southward migration of our Canada Geese and other birds.

Among the five bright planets, only three of them will be seen this month by observers in this part of the world, but those three put on a “distinctive showing” compensating for the invisibility of the other two. Jupiter, the largest of the planets, is the brightest object in the evening sky (when the moon is not present), and it is easily found low in the southwestern evening sky. As we did last month, we should watch its steady night-by-night movement to the left as it appears to approach the star called Zubenelgenubi, brightest star in the constellation Libra. On September 11^th, (Don’t miss the view that evening!) it appears extremely close to that star, and after that evening it appears to move further to the left and away from that star. In making these observations over the course of the month, you will be watching the real orbit of the planet Jupiter as it revolves around the sun.

Brilliant Venus, the brightest planet of all, is seen low in the eastern morning sky for over an hour before sunrise in early September, but for less than an hour later in the month. Saturn which appears considerably fainter than Venus, is up and slightly to the right from Venus throughout the month. Obviously, it is also seen only in morning twilight hours in the eastern sky. At the beginning of the month Venus and Saturn are separated by less than the width of a fist held at arm’s length, but as the month passes, Saturn moves further and further above Venus.

Though it is theoretically possible that someone with binoculars and a perfect view of the western horizon may catch a short glimpse of Mercury about 30 minutes after sunset during the last week of the month, we may assume that no one will be able to do so.

This month Mars will be completely impossible to see from the earth’s northern hemisphere, as indeed it was during the last half of August. (Yes, that last sentence is indeed true, yet the bizarre internet chain letter persists, and I continue to hear questions about it – the one that repeats the nonsense about a spectacular apparition of Mars on August 27^th. Remember only that the message of that letter is a lie and a hoax.)

Twice during the month the moon’s orbit around the earth will carry it into a position where it appears close to a bright planet, giving us a very pleasant sight of some of the sky’s brightest objects, appearing to be close together (even though they are of course, very far apart). In the morning sky on September 18^th and 19^th the slender waning crescent moon appears first above and then below the planet Saturn. On September 20^th the even slimmer crescent appears above Venus, if they are viewed about 40 minutes before sunrise. On the following morning, the 21^st, those luck enough to have very good observing conditions and an excellent view of the eastern horizon may catch a glimpse of the slender crescent moon EXTREMELY close to brilliant Venus Remember that, to see this superb and memorable view, you may find it helpful to have ordinary binoculars. All of these sights are worth setting the alarm. Very low in the western evening sky on September 24^th, 25^th, 26^th, and 27th, the young waxing crescent moon may be detected below and to the right from Jupiter (on the first two of those dates and to the left from Jupiter on the last two dates). Begin looking just 30 to 45 minutes after sunset. Again a very good view right down to the horizon is required and binoculars may be helpful. Try not to miss these “gems of the morning and evening sky”; clip the column to remember the dates and times.

Having gone a half-year since the last eclipse season we are now into this year’s second eclipse season. However, this one does not favour observers in North America. There is a partial lunar eclipse on September 7^th (visible in Africa, Asia, and Australia) and an annular solar eclipse on September 22^nd (visible as such in only a tiny part of South America and in the South Atlantic Ocean between South America and Africa. NO PART OF EITHER ONE OF THESE TWO ECLIPSES will be visible from anywhere in North America.

Besides the events mentioned above, there may well be opportunities to see an active display of the Aurora Borealis or ‘Northern Lights’, a passage overhead of the International Space Station which appears almost as bright as the planet Jupiter, or a sudden glow of a blazing meteor (“shooting star”) as it burns up in the upper atmosphere. Turn off any outdoor lighting that can hinder your view and your enjoyment of the sky, and “become a naturalist of the night sky”. More information about observing stars, planets, and constellations is to be found in the book called The Beginner’s Observing Guide which is available at Sharbot Lake Pharmacy and on the internet at www.rasc.ca/publications.htm.