Sky at a Glance | August 30th, 2013

Dawn view
As dawn brightens, watch the waning crescent Moon passing Jupiter, Mars, and company in the eastern sky. (Positions are drawn for the middle of North America.)

Friday, August 30

  • By about 9 p.m. now (depending on where you live), W-shaped Cassiopeia has risen as high in the northeast as the Big Dipper is in the northwest. Midway between them, and a bit higher, is Polaris. Cassiopeia will grow more ascendant over the Dipper in the coming weeks and months as the seasons turn.

  • Before dawn tomorrow morning, Jupiter shines left of the waning crescent Moon in the east. They're in Gemini, as shown at right. Look for Orion way off to their right.

    Saturday, August 31

  • Before dawn Sunday morning, the waning Moon shines inside a quadrilateral of Pollux, Jupiter, Mars, and Procyon, as shown at right.

    Sunday, September 1

  • Look east after dark for the Great Square of Pegasus balancing on one corner. Its stars are 2nd and 3rd magnitude. From the Square's left corner runs Andromeda's main line of 2nd-magnitude stars, similarly spaced.

    Click for larger view
    The Sagittarius Teapot and the surrounding rich Milky Way are highest in the south right after dark at this time of year. The brightest puff of the summer Milky Way seems to rise like steam from the Teapot's spout. All of the labeled objects here and many more are good binocular targets under a dark sky. Click the image for a larger view.
    Alan MacRobert

    Monday, September 2

  • Right after dark at this time of year, bright Vega shines almost straight overhead for skywatchers at mid-northern latitudes. Whenever Vega is highest, it's the sign that rich Sagittarius is at its highest in the south. Work through the Sagittarius area with your charts and scope before it sinks low for the night and the season.

    Tuesday, September 3

  • With the Moon out of the evening sky, now's a good time to see what you can make of the distant galaxy cluster Abell 2666. Its location is easy to find just inside the Great Square of Pegasus. But you'll need a moderately large telescope and a good sky; the cluster's brightest member, giant NGC 7768, appears 12th or 13th magnitude. If you succeed, could this be your record-farthest galaxy? The cluster is 300 million light-years away. Use the finder charts and photo with Ken Hewett-White's "Going Deep" article in the September Sky & Telescope, page 60.

    Wednesday, September 4

  • The big but dark-colored asteroid 324 Bamberga has brightened to magnitude 8.3. It's nearly at an unusually close, once-in-22-years opposition. Seek it out on the edge of the Circlet of Pisces using the finder chart in the September Sky & Telescope, page 51.

    Thursday, September 5

  • As evening twilight fades, spot Venus low in the west. Look below it (by less than 2°) for much fainter little Spica twinkling away. Binoculars help. Saturn glows 14° to their upper left.

    Friday, September 6

  • Spica remains 2° below Venus in twilight, shifted somewhat from yesterday.

    Venus is bright, but bring binoculars to help with the faint 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.

    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. And plan for the lovely Moon-Venus conjunction tomorrow!


    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).

    Once you have 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.


    This Week's Planet Roundup

    Jupiter on Sept. 3, 2013
    We're getting good looks at Jupiter again now that it's climbing higher in the east during early dawn. "Seeing was excellent this morning!" writes Philippine imager Christopher Go September 3rd.


    His fine image here shows the Great Red Spot disappearing around the preceding limb. The whitish turbulence following behind the spot has widened and lengthened since last we saw. A small white outbreak is occurring near where the turbulence rubs against the brownish South Equatorial Belt. South here is up. The North Equatorial Belt remains plainly redder than its southern equivalent. Don't expect visual views this crisp and vivid in any telescope!


    Mercury is hidden in the glare of sunset.

    Venus (magnitude –4.0) shines brightly low in the west in evening twilight, far below Arcturus. Look a little to its left for much fainter Spica early in the week, then watch Venus close in on Spica every day. It passes less than 2° above Spica on September 5th. Binoculars help. Look too for Saturn about 14° upper left of Spica.

    Mars and Jupiter shine in the east before and during dawn. Jupiter, in Gemini, is the highest and brightest (magnitude –2.0). Look for fainter Mars (magnitude +1.6, in Cancer) increasingly far to Jupiter's lower left. Off to Mars's 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 11 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.


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