Sky at a Glance | August 23rd, 2013

Bright nova in Delphinus. For news of the naked-eye nova in the evening sky that first erupted August 14th, see Bright Nova in Delphinus, which includes a finder chart and a link to a continuously updated light curve.


Friday, August 23

  • The Great Square of Pegasus, tipped up on one corner, hangs above the waning gibbous Moon after the Moon rises in mid-evening.

    Saturday, August 24

  • The asteroid 7 Iris (the 7th discovered) is just past opposition in Aquarius. Find it at magnitude 8.0 this week with a small telescope and the finder chart in the September Sky & Telescope, page 52.

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

    Sunday, August 25

  • Whenever bright Vega shines highest overhead, as it's doing after dark this week, you know that Sagittarius, rich in deep-sky objects, is at its highest and best in the south. Do your observing here early before the Moon rises around 10.

    Monday, August 26

  • The Moon rises around 11 p.m. now, about a fist-width at arm's length to the right of the Pleiades.

  • Perseus is up in good view in the northeast by late evening. By then you can catch Algol, Beta Persei, near the bottom of one of its eclipses: shining at only magnitude 3.4 instead of its usual 2.1. Mid-eclipse is around 11:54 p.m. EDT (8:54 p.m. PDT). Algol stays this dim for about two hours, and it takes several additional hours to fade and to rebrighten.

    Tuesday, August 27

  • Last-quarter Moon tonight (exact at 5:35 a.m. Wednesday morning). The Moon rises around 11 or midnight. Once it's well up in the east, look above it for the Pleiades and below it for orange Aldebaran. Well off to their left shines bright Capella.

    Wednesday, August 28

  • 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.

    Thursday, August 29

  • Off the eastern shoulder of Ophiuchus are several interesting binocular sights, including the loose open cluster IC 4665 and the evocative asterism of Taurus Poniatovii. See Gary Seronik's Binocular Highlight in the August Sky & Telescope, page 45.

    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

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

    Saturday, August 31

  • Before dawn Sunday morning, the waning Moon shines inside a quadrilateral of Pollux and Jupiter (above it) and Mars and Procyon (below it).


    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 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.


    This Week's Planet Roundup

    Mercury is hidden in the glare of the Sun.

    Venus (magnitude –4.0) shines brightly low in the west-southwest in evening twilight, far below Arcturus. Look to its left for much fainter Spica, and upper left of Spica for Saturn. In a telescope Venus is still small (14 arcseconds) and gibbous (75% sunlit).

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

    Above Mars are Pollux and Castor. Off to its right or lower right twinkles Procyon.

    Saturn (magnitude +0.7, on the border of Virgo and Libra) glows in the southwest as twilight fades, with Spica 13° to its lower right and bright Venus farther lower right.

    Uranus (magnitude 5.8, 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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