Night Skies August 5, 2004
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The Night Skies of August, 2004A Month For Morning Planets and Many Meteorsby Leo Enright
During the month of August we have more time to enjoy the night sky with its fabulous views along the Summer Milky Way, as well as the added bonus of a famous meteor shower that produces dozens of shooting stars per hour. At the beginning of August, sunset locally is at about 8:30 p.m. Eastern Daylight Time, and astronomical twilight ends at about 10:30 p.m., almost an hour earlier than in late June. By the end of August, sunset will be about 7:45 p.m., with twilight ending about 9:30 p.m.
Everyone who has grown familiar with the great Summer Milky Way can now recognize the several distinctive constellations through which it passes: Sagittarius in the shape of a teapot low in the southern sky, Cygnus the Swan, also called the Northern Cross from the shape of its star pattern, well up in the eastern evening sky and swinging overhead later in the night, and Cassiopeia, in the shape of a large letter W standing on its side in the northeastern sky. As our eyes sweep along this enormous river of starlight, from the deep southern sky to the north-northeast, we should remember that this Milky Way that we see is one huge arm of our home galaxy, the Milky Way Galaxy, which is made up of over 200 billion stars, many of them quite similar to our sun, and our sun is just one of this immense family of stars.
In August evenings, if we are under a clear, moonless sky, we can also easily see, with the unaided eye, another whole galaxy, the Andromeda Galaxy. It is a close neighbour to our galaxy, being only (!) about 2 million light-years away, and it probably contains twice as many stars as our galaxy! Look, between 10:00 p.m. and midnight, for what seems to be a faint fingerprint in the eastern sky about half way between the horizon and the zenith (the point overhead). Be sure to pause and reflect on the incredible size and distance of the object at which you are gazing, on the fact that the light hitting your eyes left that galaxy over 2 million years ago.
Among the bright planets, Jupiter continues to be the dominant planet of the evening sky, but it is much lower in the evening sky than it was a month ago. During August this trend will continue. In order to see it easily all month, you will need to have a good view of the western horizon. By the end of the month it will become difficult to see, since it will be setting only about 40 minutes after sunset. Try to observe it right to the end of the month. The two other planets of the evening sky are much more difficult to see. Mercury is found down and to the right from Jupiter by about the width of a fist held at arms length. Binoculars will be helpful in locating it about 30 to 60 minutes after sunset. Mars appears to the right of Mercury by about the width of a fist at arms length and should be seen at the same time as Mercury. Try to locate these last two planets early in the month, because they will become much more difficult to locate after August 10.
This months two morning planets, Venus and Saturn, are easier to enjoy. Venus is spectacularly brilliant, and rises over 3 hours before sunrise. It absolutely dominates the eastern sky until sunrise. Careful observers should try to follow it right up and even after sunrise. In a small telescope its appearance gradually changes from a crescent phase in early August to a quarter phase at mid-month, a very interesting transformation. Saturn rises in the east, over an hour before sunrise in early August, increasing to over 3 hours by late August. Saturn still appears in the constellation Gemini, as it has for the past year; it is just to the right of the twin stars Castor and Pollux. At any chance you have for morning observing, be sure to note that brilliant Venus and Saturn appear to be approaching each other, until by the last day of the month they are very close. Dont miss the view in the eastern sky an hour before sunrise on August 31 when Saturn and Venus will be extremely close and almost in a perfect line with the stars Castor and Pollux on the left, and Procyon and Sirius on the right, and all six of these objects to the left of the great hunter constellation, Orion.
With the coming of August, we have a greater chance of seeing meteors than at most other times of the year. The very famous Perseid Meteor Shower, so-called because these meteors appear to radiate from the area of the constellation Perseus in the north eastern sky, reaches its peak on August 12, though I have seen some of these meteors as early as June.
Perseid meteors are tiny dust particles left in a huge elliptical stream in the inner solar system from Comet Swift-Tuttle, a comet of 130-year period, that last appeared in 1862 and in 1992. Special excitement this year is about possibly seeing increased activity from the layer of dust cast off when the comet was near the sun in 1862. Perseids are very fast, travelling at 60 kilometres per second before being burned up in the atmosphere.
Some meteors are likely to be seen on any night in August, but I suggest that people make definite plans to observe them on the nights of August 11 and 12. Fortunately this year, moonlight will not interfere at all for most of the night. Although some meteors may be seen beginning at about 10:00 p.m., I strongly recommend observing all night, right up to morning twilight. Meteor experts are predicting this years best activity for early morning at the beginning of twilight. Enjoy the show from the comfort of a reclining lawn chair. To see the most meteors, face in a northerly or southeasterly direction and direct your gaze to a quarter-section of the sky quite high above the horizon. You will soon notice that most of the meteors come from, and can be traced back to, a spot, called the radiant in the northeastern sky; these meteors are members of the Perseids; others are not. Try to keep an hour-by-hour count of the Perseids seen; I would be interested in hearing the results of per-hour counts for various times during both nights suggested
Anyone interested in having more information about observing the night sky should obtain a copy of the book, The Beginners Observing Guide at Sharbot Lake Pharmacy.
