Friday, August 1
At dusk this evening, the Moon forms the lower-right end of a very long, curving line of celestial objects. Counting to the Moon's upper left, these are Spica, Mars, and Saturn, as shown here.
Today is Lammas Day or Lughnasadh, one of the four traditional "cross-quarter" days midway between the solstices and equinoxes. More or less. The actual midpoint between the June solstice and the September equinox this year comes at 2:40 a.m. August 7th Eastern Daylight Time (6:40 UT). That will be the exact center of (astronomical) summer.
Saturday, August 2
The Moon shines about midway between Spica and Mars this evening, as shown above (plotted for the middle of North America).
Sunday, August 3
The first-quarter Moon shines between Mars and Saturn as seen from the Americas and Europe, as shown above. The Moon will occult (cover) Saturn as seen from Australia, where the local date will be August 4th. Watch live via Slooh starting at 11:00 UT August 4th (7 a.m. August 4th Eastern Daylight Time in the US).
Monday, August 4
Now the Moon forms the left end of a ragged line with Saturn, Mars, and Spica to its right and lower right. To the Moon's left are the vertical row of stars forming the head of Scorpius (highlighted by Delta Scorpii, labeled δ below), and then Antares.
Tuesday, August 5
Look below the Moon this evening for the red supergiant Antares, as shown at right. Around Antares and to its right are other stars of upper Scorpius.
Wednesday, August 6
Antares is well to the lower right of the Moon this evening, as shown here. More than twice as far to the Moon's upper left shines Altair.
Thursday, August 7
Vega is the brightest star very high in the east after dusk, almost overhead. The brightest in the southeast is Altair, nearly as bright. Altair is flagged by little Tarazed (3rd magnitude) a finger-width above it: an orange giant far in Altair's background.
Friday, August 8
Look northeast as the stars come out for W-shaped Cassiopeia. It's still not as high as the Big Dipper is in the northwest, but the two are on their way to their dusk balance point week by week. Get a preview of this by checking on them around 11 p.m. (depending on your location).
Saturday, August 9
If you're in the Earth's mid-northern latitudes, bright Vega crosses close by the zenith around 10 or 11 p.m. (depending on where you are east-west in your time zone). Wherever you are, Deneb always passes the zenith two hours after Vega.
Want to become a better 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 once you know your way around, 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 fairly heavy and expensive). As Terence Dickinson and Alan Dyer say in their 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 (about magnitude –1.5) sinks very deep into the glow of sunrise this week, farther and farther to the lower left of much-brighter Venus. Scan for it with binoculars. Mercury and Jupiter are in conjunction, 1° apart, on Saturday morning August 2nd.
Venus (magnitude –3.8) shines low in the east-northeast during dawn.
Mars (magnitude +0.5, in Virgo) is in the southwest at dusk. It's about midway between Saturn to its upper left and Spica to its lower right. In a telescope Mars's tiny gibbous disk is only 8 arcseconds tall.
Jupiter (magnitude –1.8) is just beginning to emerge from the glare of sunrise far to the lower left of Venus. Jupiter and Mercury are in conjunction, 1° apart, on the morning of August 2nd; bring binoculars.
On August 18th, Jupiter will reach a much more striking conjunction with Venus higher in the dawn.
Saturn (magnitude +0.5, in Libra) shines in the southwest in twilight to the upper left of Mars.
Uranus (magnitude 5.8 in Pisces) and Neptune (magnitude 7.8 in Aquarius) are well placed in the southern sky in the early-morning hours. Use our 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) is Universal Time (UT, UTC, or GMT) minus 4 hours.