Sky at a Glance | August 30th, 2013

Venus is bright, but bring binoculars to help with the fainter objects low in the twilight. The Moon is positioned as it's seen from the middle of North America. The blue 10° scale is about the width of your fist held at arm's length.

Friday, September 6

  • As evening twilight fades, spot Venus low in the west. Look below it by 2° for little Spica twinkling much fainter. Binoculars help. Saturn glows 13° to Venus's upper left.

    Saturday, September 7

  • While twilight is still bright, use binoculars to look for the thin crescent Moon just above the western horizon to the lower right of Venus and Spica, as shown here.

  • Low before dawn, Mars passes through the Beehive star cluster Sunday and Monday mornings.

    Sunday, September 8

  • Moon and Venus paired. Look low in the west-southwest in twilight for the waxing crescent Moon with bright Venus to its right, as shown here. See article: Crescent Moon and Venus Put on a Show.

    Monday, September 9

  • This evening the Moon in twilight stands off farther left of Saturn, with Venus down to their lower right.

    Tuesday, September 10

  • Off the tail of Aquila is the Scutum Star Cloud, with the grand cluster M11 just below the dark nebula Barnard 111. See Gary Seronik's Binocular Highlight column and chart in the September Sky & Telescope, page 45.

    Wednesday, September 11

  • Altair is the brightest star shining high in the south these evenings. Look a finger-width at arm's length to its upper right for fainter Tarazed, a red giant far in Altair's background. Look a little more than a fist to Altair's left or upper left for Delphinus, the leaping Dolphin.

    Thursday, September 12

  • The big but dark-colored asteroid 324 Bamberga is reaching opposition at magnitude 8.1 — an unusually close, once-in-22-years opposition. Seek it out near the Circlet of Pisces using the finder chart in the September Sky & Telescope, page 51.

    Saturn will soon pass above Venus.

    Friday, September 13

  • Saturn has closed to within 6° of Venus, as shown at right. They'll pass 3½° apart on the 17th and 18th.

    Saturday, September 14

  • Look for bright Vega passing 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 latitude 39° north (near Baltimore, Kansas City, Lake Tahoe, Sendai, Beijing, Athens, Lisbon).


    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.

    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. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).

    Pocket Sky Atlas
    The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6 — which may sound like a lot, but that's less than one star in an entire telescopic field of view, on average. By comparison, Sky Atlas 2000.0 plots 81,312 stars to magnitude 8.5, typically one or two stars per telescopic field. Both atlases include many hundreds of deep-sky targets — galaxies, star clusters, and nebulae — to hunt among the stars.
    Sky & Telescope

    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.

    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 beloved if dated Burnham's Celestial Handbook.

    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 (able to point with better than 0.2° repeatability, which means heavy and expensive). 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

    Jupiter on Sept. 9, 2013
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    Mercury is hidden deep in the glare of sunset.

    Venus and Saturn (magnitudes –4.1 and +0.7, respectively) hang low in the west-southwest in evening twilight, far lower left of Arcturus. Venus is the brightest but lowest. Saturn glimmers to Venus's upper left, a little closer every day. The star Spica begins the week just under Venus, then moves away to its lower right. Bring binoculars to help with Saturn and Spica.

    The waxing crescent Moon pairs with Venus on the 8th — lovely! — and Saturn on the 9th, as shown at the top of this page.

    Mars and Jupiter shine in the east before and during dawn. Jupiter, in Gemini, is the highest and brightest (magnitude –2.1). Look for fainter Mars (magnitude +1.6, in Cancer) increasingly far to Jupiter's lower left. Off to Mars's right or upper right shines Procyon, somewhat brighter.

    Uranus (magnitude 5.7, in Pisces) and Neptune (magnitude 7.8, in Aquarius) are well up toward the southeast by 10 p.m. 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.


    Like This Week's Sky at a Glance? Watch our SkyWeek TV short, also playing on PBS.


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