This Week’s Sky at a Glance

Jupiter is climbing higher above faint Mars low in the dawn. And on what morning can you first pick up Mercury?

Friday, July 26

  • The Delta Aquariid meteor shower should be in its broad maximum all week. This and other weak, long-lasting July showers with radiants in the southern sky increase the chance that any meteor you see will be flying out of the south. See article.

    Saturday, July 27

  • With the Moon now gone from the evening sky, try exploring through the nest of galaxies over the back of Draco, the Dragon, using Sue French's Deep-Sky Wonders article and charts in the July Sky & Telescope, page 56. The brightest of them are 10th magnitude.

    Sunday, July 28

  • Starry Scorpius is sometimes called "the Orion of Summer" for its brightness and its prominent red supergiant (Antares in the case of Scorpius, Betelgeuse for Orion). But Scorpius is a lot lower in the sky for those of us at mid-northern latitudes. This means it has only one really good evening month: July. Catch Scorpius due south just after dark now, before it starts to tilt lower toward the southwest.

    Monday, July 29

  • Last-quarter Moon (exact at 1:43 p.m. EDT). The Moon rises around midnight tonight, shining below the stars of Aries. As it climbs higher through the morning hours, look well to its lower left for the Pleiades.

    Tuesday, July 30

  • Bright Vega shines nearly overhead these evenings, for those of us at mid-northern latitudes. Look southeast for Altair, almost as bright. Above Altair by a finger-width at arm's length is its little orange sidekick Tarazed, 3rd magnitude.

    Wednesday, July 31

  • Find Altair again high in the southeast after dark. To its right, by about a fist and a half at arm's length, is the dim but distinctive little constellation Delphinus, the Dolphin, jumping leftward.

    Thursday, August 1

  • The asteroid 3 Juno is brightest at opposition this week, glimmering at magnitude 9.0 at the Aquarius-Aquila border. Pick it up with your scope using the finder chart in the August Sky & Telescope, page 51.

    Friday, August 2

    As summer begins to wane, The Big Dipper hangs diagonally on the wall of the northwestern sky during evening. It's about as high as bright Arcturus, shining left of it in the west.

    As dawn begins to brighten on August 3rd and 4th, look for the thin Moon and three planets. This view is drawn for 1 hour before sunrise for a skywatcher at mid-northern latitudes in North America. Binoculars may help for the fainter objects. The blue 10° scale is about the size of your fist held at arm's length.
  • In early dawn Saturday morning (you can set your alarm), the waning crescent Moon hangs to the upper right of Jupiter, Mars, and Mercury low in the east-northeast, as shown at right.

    Saturday, August 3

  • During Sunday dawn an even thinner waning Moon poses to the right of the Jupiter-Mars-Mercury line, as shown at right.


    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.

    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 pretty 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

    Mercury, Mars, and Jupiter shine low in the east-northeast during dawn. Jupiter is the highest and brightest (magnitude –1.9). Look for faint Mars (magnitude +1.6) a little to Jupiter's lower left. Look below them, and perhaps a bit left, for Mercury, which brightens from magnitude +1 to 0 this week. Best time: about 60 to 40 minutes before your local sunrise. See the illustrations above. Binoculars may help with the fainter two planets, especially through summer haze.

    Venus (magnitude –3.9) shines brightly low in the west in evening twilight. In a telescope Venus is still small (12 arcseconds) and gibbous (83% sunlit).

    Double-shadowed Saturn. Saturn is near eastern quadrature during July and August (90° east of the Sun), so this is when its globe casts the widest shadow onto the rings behind as seen from Earth's viewpoint. That's the black band on the rings just off the globe at lower right of center (celestial northeast).

    Meanwhile, the rings are now casting a prominent shadow onto the globe. That's the black rim above the rings here (south is up). Both shadows add to Saturn's 3-D appearance in a telescope.

    The gray band on the globe just inside the rings is the semitransparent C Ring, the sparse "Crepe Ring," with no shadow currently behind it to confuse its appearance.

    Damian Peach took this excellent image on July 19th using the powerful stacked-video method. Don't expect Saturn to look this clear and crisp in any telescope visually!


    Saturn (magnitude +0.6, in Virgo) glows in the southwest just after dusk, with Spica 12° to its lower right. Look almost as far to Saturn's left for fainter Alpha Librae. Less than 0.9;° upper right of Saturn this week is dim Kappa Virginis, magnitude 4.3.

    Uranus (magnitude 5.8, in Pisces) and Neptune (magnitude 7.8, in Aquarius) are nicely placed in the southern sky before the beginning of dawn. 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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