Friday, Aug. 31 Full Moon (exact at 9:58 a.m. EDT). This is a "blue Moon," when the term refers to the second full Moon in a calendar month. Blue Moons come once every 2.7 years on average. The next is on July 31, 2015. This week, right after dark is the time when the Big Dipper descends to the same height in the northwest as Cassiopeia rises in the northeast. Henceforth it will officially be Cassiopeia season. Look for Polaris midway between them (and a bit above).
Saturday, Sept. 1 This week, bright Vega passes the zenith as twilight fades away if you live in the world's mid-northern latitudes. Vega goes right through your zenith if you're at north latitude 39°: near the latitudes of Baltimore, Kansas City, Lake Tahoe, Sendai, Beijing, Athens, Lisbon.
Sunday, Sept. 2 The waning gibbous Moon rises in late twilight. It's beneath the uptilted Great Square of Pegasus.
Monday, Sept. 3 As twilight fades this week, spot bright Arcturus high in the west. Look far to its lower left for Saturn and Mars. They're about a fist-width at arm's length apart. Mars is the one on the left.
Compare Mars with similarly bright and similarly colored Antares ("Anti-Mars" in Greek), three fists to its left and perhaps higher. Which of the two looks deeper orange?
Tuesday, Sept. 4 Face south soon after dark and look high. The brightest star there is Altair, with dimmer Tarazed a finger-width at arm's length above it and a bit to the right.
Look left of Altair, by a bit more than a fist-width, for the dim but distinctive little constellation Delphinus, the Dolphin, splashing in the edge of the Milky Way. For more on Delphinus, its legendry, and telescopic double stars, see the September Sky & Telescope, page 47.
Wednesday, Sept. 5 One of the nicest star clusters for binoculars or a telescope is M11 in Scutum just off the tail of Aquila, the Eagle, as most amateur astronomers know. But can you also spot dimmer, more difficult M26 less than 4° below it? See the finder chart with Gary Seronik's "Scutum Odd Couple" in the September Sky & Telescope, page 45.
Thursday, Sept. 6 Whenever Vega is near the zenith, as it is just after dark now, you know Sagittarius is at its highest and best in the south displaying the deep-sky riches of the summer Milky Way to their best advantage. The Teapot asterism of Sagittarius is tilting to pour to the right. The richest big patch of the Milky Way, the Large Sagittarius Star Cloud, is just above its spout.
Right after dark the Sagittarius Teapot stands highest in the south, with the Large Sagittarius Star Cloud above its spout like a puff of steam. Binoculars will show the two nebulae labeled here.
Friday, Sept. 7
Jupiter and the last-quarter Moon rise together around 11 or midnight, depending on where you live. Watch for them coming over the east-northeast horizon, and look for fainter Aldebaran to their right. They continue climbing high up the sky until dawn Saturday morning when the three shine high in the southeast over Orion, as shown here.
Up before dawn? Watch the Moon wave from morning to morning as if passes between Jupiter and Aldebaran. (The scene is drawn for the middle of North America. European observers: move each Moon a quarter of the way toward the one for the previous date. The Moon is shown three times actual size.)
Saturday, Sept. 8 It's still summer, but look low in the southeast after about 9 p.m. this week (depending on where you live) and there's 1st-magnitude Fomalhaut, the Autumn Star, already making its seasonal appearance.
Want to become a better amateur astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.
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. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).
Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts).
The standards are the little Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger and deeper Sky Atlas 2000.0 (stars to magnitude 8.5); and the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope effectively.
Sky Atlas 2000.0 (the color Deluxe Edition is shown here) plots 81,312 stars to magnitude 8.5. That includes most of the stars that you can see in a good finderscope, and typically one or two stars that will fall within a 50× telescope's field of view wherever you point. About 2,700 deep-sky objects to hunt are plotted among the stars.
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, the bigger Night Sky Observer's Guide by Kepple and Sanner, or the classic if dated Burnham's Celestial Handbook.
Can a computerized telescope replace charts? I don't think so not for beginners, anyway, and especially not on mounts and tripods that are less than top-quality mechanically (able to point with better than 0.2° repeatability). As Terence Dickinson and Alan Dyer say in their invaluable 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 Roundup
Mercury is lost low in the glow of sunrise.
Venus (magnitude 4.3, in Gemini) rises in darkness around 3 a.m. daylight saving time (depending on where you are), emerging above the east-northeast horizon like a witching-hour UFO a good two hours before the first glimmer of dawn. By dawn Venus is blazing high in the east vastly outshining Pollux and Castor to its upper left and Procyon to its right or lower right.
Mars (magnitude +1.2, in Libra) and Saturn (magnitude +0.8, in Virgo) are low in the west-southwest in twilight. This week they widen from 10° to 13° apart: a fist-width at arm's length or more. Look for them far lower left of bright Arcturus. Saturn is the one on the right. You may still be able to see Spica twinkling 5° below Saturn.
Jupiter (magnitude 2.3, in Taurus) rises in the east-northeast around 11 or midnight daylight saving time. Once it's well clear of the horizon, look for fainter orange Aldebaran twinkling 6° or 7° to its right. By dawn Jupiter shines very high in the south-southeast, 40° or 45° upper right of brighter Venus.
The side of Jupiter away from the Great Red Spot on August 23rd. South is up. The huge, reddish northern-hemisphere belt is resolving itself back into the North Equatorial Belt (NEB) and, below it here, the North Temperate Belt (NTB), with the light North Tropical Zone re-emerging between them. Notice the thin, unusual Equatorial Band in the middle of the bright Equatorial Zone.
John H. Rogers, the British Astronomical Association's Jupiter Section director, says the recent regrowth of the NEB is its first "full-scale revival" since 1926, "and the NTB is reviving via a super-fast jet-stream outbreak as last seen in 2007. Sectors of the belts and the intervening NTropZ which were still light in June have now filled in with intense turbulence and reddish (ochre) colour, producing one
vast brown-and-ochre belt from the NEBs to the NTB."
Uranus (magnitude 5.7, at the Pisces-Cetus border) and Neptune (magnitude 7.8, in Aquarius) reach good heights in the southeast by mid- to late evening. Finder charts for Uranus and Neptune.
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) equals Universal Time (also known as UT, UTC, or GMT) minus 4 hours.
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