Longer nights, cooler days and drier air – whats not to like about September! After summer’s haze and short nights, astronomers really get back to business in the fall and winter. September will be a great month for star gazing as the planets re align and a comet pays a visit to the inner solar system. I hope you had a chance to see the Perseids meteor shower last month. We gathered up family and friends and reclined on blankets in our driveway and saw a dozen or so and a couple that were really bright.
The planets – Jupiter, the king of planets, makes a truly dashing appearance this month. In fact, it will be the closest it gets to the Earth in its 12 year orbit about the Sun. It will also be brighter and larger than its been in almost 45 years as its elliptical orbit brings it closest to the Earth at opposition. Opposition means it is exactly opposite the Earth in line with the Sun and thus rises at dusk and sets at dawn all month. It will be the second brightest planet in the sky after Venus which will be low in the western sky at sunset. Through a small telescope or binoculars you should be able to see Jupiter’s brighter moons; Ganymede, Callisto, Io and Europa, which will look like a line of bright stars on either side of the giant planet. Jupiter has planetary company in the sky this month as Uranus follows it near its opposition. On the 22nd it will be within 1 degree of Jupiter and will be very dim by comparison but visible through binoculars. Several folks have asked about the bright star near Venus – its Spica and appears between Venus and Mars early in the month. Be sure to check out Venus through a small telescope or binoculars. Like the moon it goes through phases as it orbits the sun and this month it will go from approximately one half to one-fifth phase as its orbit brings it closer to the Earth and makes it appear much larger. Also you may be able to see Mercury very bright and well below Venus just after the Sun sets. On our way back from the pot luck supper on the 30th we caught a brief glimpse as we were driving back.
Comets are notoriously unpredictable beasts but be on the look out for Comet Hartley. It is gradually getting brighter as it approaches the Sun and should be visible through binoculars late in the month. NASA’s Deep Impact spacecraft will fly by it and take photos in early November. Best hope to see it will be in November and December but if you are determined you can google a finder chart and try to see it.
On September 22nd at exactly 11:13 PM EDT the autumnal equinox occurs. This is the point in the Earth’s orbit when the Sun is perpendicular to the equator and days and nights are of equal length. Nothing to see but it marks the transition from summer to fall with gradually shorter days and longer nights.
A brief word about lights – please turn them off! Light pollution is a growing problem in our cities both big and small. The skies at Balsam are about as dark as it gets on the east coast so we all need to do what we can to preserve them. The BMP Habitat Review Board wisely restricts outside lighting. Numerous studies have shown that nighttime lighting negatively impacts wildlife and does not deter crime. If you have outside lights set your timer to turn them off after midnight or better yet use a motion sensor. For more information on what you can do to control light pollution visit www.darksky.org/.
Lastly, don’t forget to come to the Trust Talk at 7:30 PM on September 9th at the Stratigos residence aka Dogstar Observatory. I will give a general introduction to astronomy and the scope and scale of the universe with star gazing afterwards, weather permitting. Check the Trust web site www.bmtrust.org/ for latest details.
Thats all for this month – Go out at night, turn out the lights and enjoy the dark skies.
Jim Stratigos
Resident Astronomer