Friday, Sept. 13
• Full Harvest Moon (exact at 11:33 p.m. Central Daylight Time / 12:33 a.m. September 14th Eastern Daylight Time). The Moon rises in the east shortly after sunset for North America, a lovely sight as twilight descends. After dark, look upper left of the Moon for the Great Square of Pegasus balancing on one corner (outside the frame above). The Square is made of 2nd- and 3rd-magnitude stars.
And then watch for 1st-magnitude Fomalhaut rising to the Moon's lower right, by about two fists at arm's length. How early can you see it? The farther south you live, the higher and easier Fomalhaut will be. The sky scenes here are always drawn for latitude 40° north.
Saturday, Sept. 14
• By the end of twilight the bright Moon is shining low in the east. Look a couple of fists to its upper left for the Great Square of Pegasus, tipped onto one corner. The Square's lower left side points diagonally down at the Moon.
Sunday, Sept. 15
• Now the Moon rises around the end of twilight. Watch for it to come above the horizon due east, below the Great Square of Pegasus.
Monday, Sept. 16
• As autumn approaches (the equinox is on the night of September 22-23 this year), the Sagittarius Teapot moves west of south and tips increasingly far over to the right during evening, as if pouring out the last of summer. Spot the Teapot under Saturn.
Tuesday, Sept. 17
• You know the season is changing; we've reached the time of year when, just after nightfall, Cassiopeia has already climbed a little higher in the northeast than the Big Dipper has sunk in the northwest. Cas reigns high in early evening during the chilly fall-winter half of the year. The Big Dipper takes over for the milder evenings of spring and summer.
Almost midway between them stands Polaris. It's currently a little above their midpoint.
Wednesday, Sept. 18
• This is the time of year when the rich Cygnus Milky Way crosses the zenith in early evening (for skywatchers at mid-northern latitudes). The Milky Way extends straight up from the southwest horizon, passed overhead, and runs straight down to the northeast.
Thursday, Sept. 19
• In the west off to the Big Dipper's left, bright Arcturus, the "Spring Star," shines a little lower at nightfall each week. From Arcturus, the narrow kite-shaped pattern of Bootes extends 24° to the upper right.
• If you're up before dawn Friday morning, you'll find the waning gibbous Moon high with Aldebaran near it, as shown above.
Friday, Sept. 20
• These moonless evenings are a good time to bring out your binoculars and try for the unusually small, compact open cluster NGC 7160 in the rich center of Cepheus, now high in the north — as Matt Wedel tells in his Binocular Highlight, with finder chart, in the center of the September Sky & Telescope.
Saturday, Sept. 21
• Last-quarter Moon (exact at 10:41 p.m. Eastern Daylight Time). Tonight the Moon rises around midnight daylight-saving time, depending on your location. Watch for it to clear the east-northeast horizon lower right of Capella and lower left of the Pleiades.
By the first sign of Sunday's dawn the Moon shines high in the southeast, now with Orion to its lower right and Gemini to its lower left. How often do you examine the Moon with your telescope when the Moon is its late-night waning phases? To most of us, the waxing Moon of evening is much more familiar — when lunar mountains and crater walls cast their shadows in the opposite direction.
• Summer's not quite over yet! The September equinox this year comes at 3:50 a.m. September 23rd EDT.
Want to become a better astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.
This is an outdoor nature hobby. For an easy-to-use constellation guide covering the whole evening sky, use the big monthly map in the center of each issue of Sky & Telescope, the essential guide to astronomy.
Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The basic standard is the Pocket Sky Atlas (in either the original or Jumbo Edition), which shows stars to magnitude 7.6.
Next up is the larger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; nearly three times as many. The next up, once you know your way around, are the even larger Interstellarum atlas (stars to magnitude 9.5) and Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope.
You'll also want a good deep-sky guidebook, such as Sue French's Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, or the bigger Night Sky Observer's Guide by Kepple and Sanner.
Can a computerized telescope replace charts? Not for beginners, I don't think, and not on mounts and tripods that are less than top-quality mechanically (meaning heavy and expensive). And as Terence Dickinson and Alan Dyer say in their Backyard Astronomer's Guide, "A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand."
This Week's Planet RoundupMercury, Venus, and Mars are out of sight behind the glare of the Sun.
Jupiter (magnitude –2.1, between the feet of Ophiuchus) is the white dot hanging in the south-southwest as twilight fades away. Get your scope on it early before it sinks lower into even poorer seeing. Orange Antares, much fainter at magnitude +1.0, twinkles 8° to Jupiter's lower right. In a telescope, Jupiter is only 37 arcseconds wide and shrinking.
Saturn (magnitude +0.4, in Sagittarius) is the steady yellow "star" in the south during and after dusk, 28° left or upper left of Jupiter. Below Saturn is the handle of the Sagittarius Teapot. Much closer above it is the dimmer, smaller bowl of the Teaspoon.
Uranus (magnitude 5.7, in Aries) is well up in the east by 11 p.m. daylight saving time and highest in the south around 3 a.m.
Neptune (magnitude 7.8 and just past opposition) is still just west of 4th-magnitude Phi Aquarii. It's well up in the southeast by about 10 p.m. and highest in the south around midnight. See Bob King's Observe Neptune as it Comes to Opposition. Actually, Neptune is so distant that it's hardly any closer in the weeks near opposition than at any other time.
All descriptions that relate to your horizon — including the words up, down, right, and left — are written for the world's mid-northern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America.
Eastern Daylight Time (EDT) is Universal Time (UT, UTC, GMT, or Z time) minus 4 hours.
Audio sky tour. Out under the evening sky with your earbuds in place, listen to Kelly Beatty's monthly podcast tour of the heavens above. It's free.
"The dangers of not thinking clearly are much greater now than ever before. It's not that there's something new in our way of thinking, it's that credulous and confused thinking can be much more lethal in ways it was never before."
— Carl Sagan, 1996