It's Perseid meteor week! The shower peaks on the night of August 11th (see below), but you may see the occasional Perseid on any night at this time of year. Perhaps you already have?
FRIDAY, AUGUST 7
■ Jupiter and Saturn continue to dominate the southern sky these evenings, like a wide pair of unequal eyes. How early in twilight can you see them both? And how much darker does it have to get for the Sagittarius Teapot to emerge into view to Jupiter's right?
■ Bright Vega passes closest to overhead around 10 or 11 p.m. this week, depending on how far east or west you are in your time zone. How closely it misses your zenith depends on how far north or south you are. It passes right through your zenith if you're at latitude 39° north (Washington DC, Cincinnati, Kansas City, Lake Tahoe). How closely can you judge this just by looking?
Deneb crosses its closest to the zenith almost exactly two hours after Vega. Deneb passes exactly overhead at latitude 45° north: Portland, Minneapolis, Montreal, southern France, northern Italy.
SATURDAY, AUGUST 8
■ Mars and the waning gibbous Moon rise together around 11 p.m. or so (daylight saving time), only 2° or 3° apart for North America. By midnight they're quite the spectacle shining low in the east; Mars has brightened to magnitude –1.2, almost Sirius-bright, on the way to its October opposition.
Sunday's dawn, August 9th, finds them very high in the south, now as little as 1° apart depending on where you are.
SUNDAY, AUGUST 9
■ Different people have an easier or harder time seeing star colors, especially subtle ones. To me, the tints of bright stars stand out a little better in the deep blue of late twilight than in complete dark.
For instance, the two brightest stars of summer are Vega, now almost overhead in late twilight, and Arcturus, shining in the west. Vega is white with just a touch of blue. Arcturus is a yellow-orange giant. Do their colors stand out a little better for you before dark? Could this be a contrast effect of seeing yellow, orange, or orange-red stars on a blue background?
In any case, binoculars or a telescope will make star colors much more obvious.
MONDAY, AUGUST 10
■ The brightest star high in the southeast these evenings, high to the upper left of Jupiter and Saturn, is Altair. Look for little orange Tarazed above it by a finger-with at arm's length. Hardly more than a fist-width to Altair's left is delicate Delphinus, the Dolphin, leaping left.
Slightly less far above or upper left of Altair, look for smaller, fainter Sagitta, the Arrow. It too points left.
TUESDAY, AUGUST 11
■ Last-quarter Moon (exactly so at 12:45 p.m. EDT).
■ The Perseid meteor shower should be at its strongest late tonight. But the Moon (in Taurus) rises around midnight, and its light will interfere somewhat during the prime meteor hours from midnight to dawn. So you might do best before then, from about 11 p.m. through moonrise.
Layer up warmly even if the day was hot; remember about radiational cooling under a clear, open sky! A sleeping bag makes good mosquito armor, and use DEET where you remain exposed.
Bring a reclining lawn chair to a dark, open spot where no local lights get in your eyes. Lie back, and and gaze up into the stars. Be patient. As your eyes adapt to the dark, you may see a meteor every minute or so on average as night grows late. You'll see fewer under light pollution, but the brightest ones will still shine through.
The best direction to look is wherever your sky is darkest, usually overhead. The shower's radiant (the meteors' perspective point of origin, if you could see them coming from far away in space) is in northern Perseus under Cassiopeia. But the meteors only become visible when they hit the upper atmosphere, anywhere in your sky.
Gianluca Masi's live feed from Europe starts at 22:00 UT (6 p.m. EDT). Here's the International Meteor Organization's activity graph of the shower so far, based on meteor watchers' counts, done by carefully standardized methods, coming in from around the globe.
WEDNESDAY, AUGUST 12
■ The Big Dipper hangs diagonally in the northwest after dark. From its midpoint, look to the right by about three fists at arm's length to find Polaris (not very bright at 2nd magnitude) glimmering due north in the same place as always.
Polaris is the end of the Little Dipper's handle. The only other Little Dipper stars that are even modestly bright are the two forming the outer end of its bowl: 2nd-magnitude Kochab and 3rd-magnitude Pherkad. On August evenings you'll find them to Polaris's upper left (by about a fist and a half). They're called the Guardians of the Pole, since they ceaselessly circle around Polaris throughout the night and throughout the year.
■ Saturn's largest moon Titan is visible in a 3-inch telescope at magnitude 8.5. This evening, find it four ring-lengths west of Saturn. Can you make out its orange tint?
■ The thick waning crescent Moon rises around 1 a.m. with orange Aldebaran, the eye of Taurus, only about 3° to its lower right. By early dawn Thursday morning, they're high in the east-southeast — with Orion below them and brilliant Venus to their lower left.
THURSDAY, AUGUST 13
■ As summer progresses and Arcturus moves down the western sky, the kite figure of Bootes that sprouts from Arcturus tilts to the right. The kite is narrow, slightly bent with its top leaning right, and 23° long: about two fists at arm's length. Arcturus is its bottom point where the stubby tail is tied on.
Off to the Kite's right in the northwest, the Big Dipper slants diagonally.
FRIDAY, AUGUST 14
■ Double shadow on Jupiter. Late tonight, the shadows of Jupiter's moons Ganymede and Io are both on the planet's face at once, as two tiny black dots — from 12:08 to 1:54 a.m. EDT. (Subtract 3 hours to get PDT.)
And, Jupiter's Great Red Spot should cross the planet's central meridian around 11:26 p.m. EDT.
■ Look east in early dawn Saturday morning for Venus paired beautifully with the waning crescent Moon. They're only 3° or 4° apart for the Americas.
They shine in the feet of Gemini. If you're in the world's mid-northern latitudes, look for Orion to their right or lower right. Castor and Pollux are to their lower left.
SATURDAY, AUGUST 15
■ August is prime Milky Way time! After dark, the Milky Way extends up from low in the the south (where it runs between the tail of Scorpius and the spout of the Sagittarius Teapot), up and left across Aquila and through the big Summer Triangle very high in the east, and on down through Cassiopeia to Perseus now rising low in the north-northeast.
This Week's Planet Roundup
Mercury is hidden deep in the sunrise.
Venus (magnitude –4.5, moving across the top of Orion's Club into the feet of Gemini) rises in deep darkness about two hours before dawn begins. As dawn gets under way, Venus blazes brightly in the east. To its right or lower right is the main pattern of Orion. The brightest star high upper left of Venus is Capella.
In a telescope Venus is near dichotomy, just about half lit.
Mars rises in the east about an hour after the end of twilight. It shines bright (magnitude –1.2) yellow-orange near the Knot of Pisces, like a far-off bonfire. Where will it come up? Watch the horizon far below the Great Square of Pegasus.
By early dawn Mars shines grandly high and bright in the south, a high-blown firespark.
In a telescope this week Mars grows from 15½ to 16½ arcseconds in apparent diameter, bigger than at some oppositions! But we're still speeding toward it along Earth's faster orbit around the Sun, and we have a long way to go. When we catch up to Mars in early October around opposition, it will be 22.6 arcseconds wide.
Mars is currently gibbous, 88% sunlit. Look for its white South Polar cap and subtler dark surface markings. To get a map of the side facing you at the date and time you'll observe, use our Mars Profiler. The map there is rectangular; remember to mentally wrap it onto the side of a globe. (Features near the map's edges become very foreshortened.)
Jupiter and Saturn (magnitudes –2.7 and +0.2, respectively) shine in the south-southeast in twilight. They pass highest in the south around 11 p.m. daylight-saving time. Jupiter is the brightest; Saturn is 8° to its left.
Lower right of Jupiter after dark is the handle of the Sagittarius Teapot. High to the planets' upper left, the brightest star is Altair.
Keep up with the telescopic interplay of Jupiter with its moons and their shadows, and find all the transit times of Jupiter's Great Red Spot, in the Celestial Calendar section of the August Sky & Telescope, page 50.
Uranus (magnitude 5.8, in Aries) is well up in the east by 1 a.m. daylight-saving time, nearly 20° to the celestial east of Mars.
Neptune (magnitude 7.8, in Aquarius) is high in the southeast at that time, more than 30° west of Mars. 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 (also known as UT, UTC, GMT, or Z time) minus 4 hours.
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 magazine of astronomy.
Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The basic standard is the Pocket Sky Atlas (in either the original or Jumbo Edition), which shows stars to magnitude 7.6.
Next up is the larger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; nearly three times as many. The next up, once you know your way around, are the even larger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope.
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, meaning heavy and expensive. And 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."
Audio sky tour. Out under the evening sky with your
earbuds in place, listen to Kelly Beatty's monthly
podcast tour of the heavens above. It's free.
"The dangers of not thinking clearly are much greater now than ever before. It's not that there's something new in our way of thinking, it's that credulous and confused thinking can be much more lethal in ways it was never before."
— Carl Sagan, 1996
"Facts are stubborn things."
— John Adams, 1770