September is my favorite month for stargazing. Nightfall comes earlier, so one doesn’t need to wait until very late to enjoy the dark skies. Our northwest weather is usually still nice, with many nights of clear skies and comfortable temperatures. Here in Trout Lake, about 2/3 of nights are still clear.
The planets Mars and Saturn are still visible in September, low in the southern sky. Both are moving away from the Earth and becoming fainter, but you can still view Saturn’s magnificent rings through a telescope. Jupiter and Venus are visible very low in the west, just after sunset. Jupiter slips below the horizon by mid-month.
The two outer planets, Uranus and Neptune, deserve mention too. On Sept. 2, Neptune will be at opposition, closest to Earth. It will be pretty low in the evening sky in September, and better to view in coming couple of months. The same is true for Uranus, which will come into opposition in mid-October.
Mercury will be visible in September’s morning sky, late in the month. Look for the bright planet due east before sunrise. On Sept. 29, a very thin, waning crescent Moon will lie just below Mercury in the early morning sky, a treat for early-bird sky watchers.
The Moon will be “new” on Sept. 1. On Sept. 8, the first-quarter Moon will lie just above Saturn and Mars, in the southern sky. Full Moon will be on Sept. 16. We’ll have a second new Moon on the last day of September.
This year the first day of fall, the autumnal equinox, comes on Sept. 22. At 7:21 a.m. PDT. At that time, the Sun will lie directly above the equator, and the length of our days and nights will be approximately equal. By the end of September, we’ll be down to 11 hours and 42 minutes of daylight.
Fall constellations are beginning to rise in the east during September. Pegasus will be easy to pick out in the evening sky. The constellation’s “Great Square” is visible, made up of 4 almost identically luminosity, forming an almost perfect square.
To the right of Pegasus lie two small constellations, Delphinius (the Dolphin) and Equuleus, the foal or “little horse.” Delphinius does not contain any very bright stars, but its brightest members make up a shape that does resemble a fish or dolphin. See if you can make it out. Equuleus, one of the smallest and faintest constellations, lies below Delphinius, and doesn’t contain any stars of noticeable brightness.
As always, a good way to enjoy the night skies is to visit the Goldendale Observatory. Our unique State Park is undergoing some improvements, including the main telescope. The scope was removed in late July, but should be back in place by September (I’m writing this in mid-August). A smaller, portable telescope is being used during the interim, one that still provides very nice views of celestial objects. The main scope is being changed to allow for wider fields of view and brighter images, a significant improvement!