This Week’s Sky at a Glance, August 14 – 22 – Sky & Telescope


■ How early in twilight can you see Jupiter after which Saturn glimmering into view? Look for them within the south-southeast, as proven beneath. (To their proper, you will want binoculars to select the Sagittarius Teapot stars till twilight is sort of over.)Later the Jupiter-Saturn pair turns completely horizontal, a little earlier every night time. How nicely are you able to choose when this occurs? The precise time will depend upon the place you reside in your time zone. But count on it to occur about 4 minutes earlier with every passing day.

Jupiter, magnitude –2.6 this week, outshines Saturn, magnitude +0.2, by 13 occasions. (The formulation, for many who have requested: If DeltaM is the distinction between two magnitudes, the brightness distinction between them, when it comes to the precise quantity of sunshine, is 2.512DeltaM .)■ Double shadow on Jupiter. Late tonight, Jupiter’s moons Ganymede and Io each solid their tiny black shadows onto the planet’s face at as soon as from 12:08 to 1:54 a.m. EDT. The central and western states have probably the most handy view of Jupiter through the occasion; subtract Three hours from these occasions to get PDT.And, Jupiter’s Great Red Spot ought to cross the planet’s central meridian earlier than then, round 11:26 p.m. EDT.

■ In early daybreak Saturday morning, look east for Venus paired fantastically with the waning crescent Moon, as proven beneath. They’re solely 3° or 4° aside for the Americas, shining within the dim ft of Gemini.Look for Castor and Pollux to their decrease left. Orion is farther to their proper or decrease proper.


■ August is prime Milky Way time! After darkish, the Milky Way extends up from low within the the south (the place it runs between the tail of Scorpius and the spout of the Sagittarius Teapot), up and left throughout Aquila and thru the massive Summer Triangle very excessive within the east, and on down by way of Cassiopeia to Perseus rising low within the north-northeast.

■ Here’s a little-identified Milky Way sight: In southwestern Scorpius close to Lupus, off the deep-sky observer’s overwhelmed monitor, is the modest open cluster NGC 6124. It’s sixth magnitude in complete, however its stars are scattered throughout about 0.7°, so it is not a lot to look at in binoculars or a large-area scope.But it should be. As Matt Wedel remarks within the August Sky & Telescope’s Binocular Highlight (web page 43), this cluster is comparatively close by at only one,700 mild years, however it’s darkened by at least three totally different clouds or sheets of interstellar mud alongside our line of sight to it, in addition to mud inside the cluster itself. Were the view mud-free, he says, NGC 6124 would shine “as bright and prominent as some of the showier Messier clusters.”Use his chart there to search out it. Look instantly after darkish; it is fairly low and shortly to get decrease. The farther south you’re the higher.

■ Early within the daybreak of Sunday the 16th, Pollux and Castor shine left of the waning crescent Moon, as proven above.


■ Whenever vibrant Vega crosses nearest your zenith, because it does quickly after darkish now, you understand that the Sagittarius Teapot is at its highest due south.

Two hours later when Deneb crosses closest to the zenith, it is the flip of little Delphinus and boat-formed Capricornus down beneath to face at their highest due south.

■ In early daybreak Monday morning the 17th, you will discover the skinny crescent Moon method down underneath Pollux and Castor, as proven above.


■ The brightest star excessive within the southeast these evenings, excessive to the higher left of Jupiter and Saturn, is Altair. Look for little orange Tarazed above it by a finger-width at arm’s size. Altair is just 17 mild-years away. Tarazed (Gamma Aquilae) is a purple large about 400 mild-years within the background.Hardly greater than a fist-width to Altair’s left is delicate Delphinus, the Dolphin, leaping left: towards the east.

Slightly much less far above or higher left of Altair, search for smaller, fainter Sagitta, the Arrow. It too factors east.


■ As August proceeds and nights start to show chilly, the Great Square of Pegasus looms up within the east, balancing on one nook. Its stars are solely 2nd and third magnitude, and your fist at arm’s size suits inside it. Down beneath it, glary Mars rises lower than an hour after darkish.

From the Great Square’s left nook runs the principle line of the constellation Andromeda: three stars (together with the nook) about as vibrant as these forming the Square. The line extends left and a bit down.

This entire large sample was named “the Andromegasus Dipper” by the late Sky & Telescope columnist George Lovi. It’s formed kind of like a large Little Dipper with an additional-large bowl, and it is at present lifting its contents upward.

■ New Moon (precise at 10:42 p.m. EDT).


■ The precise Little Dipper, in the meantime, is tipping over leftward within the north. It’s solely 40% so long as the Andromegasus Dipper, and most of it’s a lot fainter. As all the time, you will discover that it is oriented greater than 90° counterclockwise in comparison with Andromegasus. It’s dumping its contents out.


■ As summer season progresses and Arcturus strikes down the western sky, the kite determine of Bootes that sprouts from Arcturus tilts to the fitting. The kite is slim, barely bent with its high leaning proper, and 23° lengthy: about two fists at arm’s size. Arcturus is its backside level the place the stubby tail is tied on.

Off to the Kite’s proper within the northwest, the Big Dipper slants diagonally.


■ Spot the skinny crescent Moon low within the west in twilight. Look to its left by about 16° for Spica twinkling into view. Spica, normally thought of a star of spring, is heading down and out for the yr.

Much nearer to the Moon (for the Americas) is fainter Gamma Virginis, proven on the plot beneath. They’re simply a diploma or two aside as seen at the occasions of nightfall for North America.

The Moon on the 21st poses close to Gamma Virginis, magnitude 2.7. On the 22nd the Moon hangs over Spica, magnitude 1.0. The Moon right here is all the time drawn about thrice its precise obvious dimension, so do not choose the celebs’ distances from the Moon by the Moon’s dimension right here. ■ Another double shadow transit on Jupiter. On Friday night time Io and Ganymede are each casting their tiny black shadows onto the face of Jupiter, this time from 11:32 p.m. to 1:20 a.m. Pacific Daylight Time. This occasion is for westerners.


■ Late these evenings Fomalhaut, the Autumn Star, makes its inevitable look above the southeast horizon. Its rising time will depend upon the place you reside. But by 10 or 11 p.m. now, you should not have any bother figuring out it low within the southeast if in case you have a good view in that route. No different 1st-magnitude star is anyplace close by.


This Week’s Planet Roundup

Mercury is hidden along side the Sun.

Venus (magnitude –4.4, within the ft of Gemini) rises in deep darkness about two hours earlier than daybreak begins, a bizarre UFO of a factor within the east-northeast. As daybreak will get underneath method, Venus blazes brightly up within the east. You’ll discover Castor and Pollux off to its left and Orion farther to its proper. The brightest star excessive higher left of Venus is Capella.In a telescope Venus is close to dichotomy, half lit.

Mars rises within the east about an hour after the tip of twilight. It emerges Sirius-bright (magnitude –1.4) and strongly orange, like a far-off bonfire. Where will it come up? Watch the horizon far beneath the Great Square of Pegasus.By early daybreak Mars shines grandly excessive and vibrant within the south, now a excessive-blown firespark. It’s close to the dim Knot of Pisces.In a telescope this week Mars grows from 16½ to 17½ arcseconds in obvious diameter. That’s larger than at some oppositions, however we’re nonetheless approaching Mars as we pace alongside our quicker orbit across the Sun. When we catch as much as and move Mars at opposition in early October, it can seem 22.6 arcseconds large and can shine at a Jupiter-bright magnitude –2.6, thrice as vibrant as now.

Mars remains to be gibbous, 89% sunlit. Look for its white South Polar cap, attainable clouds particularly close to the limb, and subtler darkish floor markings. To get a map of the facet dealing with you at the date and time you will observe, use our Mars Profiler. The map there may be sq.; keep in mind to mentally wrap it onto the facet of a globe. (Features close to the map’s edges turn into very foreshortened.)

Mars on August 12th, imaged by Enrico Enzmann and Damian Peach with a 76cm (30-inch) telescope. South is up. The South Polar Cap has shrunk vastly with the advance of summer season in Mars’s southern hemisphere. The mud within the Martian ambiance that hazed the view a month in the past appears gone. The giant, darkish spherical characteristic close to the terminator higher left of heart is Solis Lacus and its environment. The giant, wavy darkish band working towards the fitting limb is Mare Sirenum. In from the underside proper limb, low-distinction Olympus Mons is clearly recorded. The solely signal of cloud is the refined fringe of the North Polar Cloud Hood alongside the underside limb. Jupiter and Saturn (magnitudes –2.6 and +0.2, respectively) shine within the south-southeast in twilight. They’re highest within the south, for sharpest telescopic viewing, round 10 or 11 p.m. daylight-saving time. Jupiter is the brightest; Saturn is 8° to its left.Lower proper of Jupiter after darkish is the deal with of the Sagittarius Teapot, as proven at the highest of this web page.Follow the telescopic interaction of Jupiter with its moons and their shadows, and discover all of the transit occasions of Jupiter’s Great Red Spot, within the Celestial Calendar part of the August Sky & Telescope, web page 50.

Jupiter with Callisto in transit, imaged by Christopher Go on August 11th at 13:22 UT. South right here is up. Callisto has the darkest floor of Jupiter’s 4 main moons, and its darkness is exaggerated by the distinction enhancement on this picture. But even visually, Callisto in transit (a pretty unusual sight) is commonly mistaken for a satellite tv for pc’s shadow.Writes Go, “This is the region [following] the Great Red Spot. The North Equatorial Belt is very active in this region; complex rifts and [white] outbreaks. The South Equatorial Belt is very pale in this region.” Callisto is seen in entrance of the slim, white North Temperate Zone.Saturn on July 27th, simply a week after opposition, imaged by Damian Peach and Enrico Enzmann. South is up. The ring tilt has modified simply sufficient that solely a hint of the globe peeks up from behind the rings’ south edge.Uranus (magnitude 5.8, in Aries) is nicely up within the east by midnight or 1 a.m. daylight-saving time, practically 20° to the celestial east of Mars.

Neptune (magnitude 7.8, in Aquarius) may be very excessive within the southeast by then. Finder charts for Uranus and Neptune.

All descriptions that relate to your horizon — together with the phrases up, down, proper, and left — are written for the world’s mid-northern latitudes. Descriptions that additionally depend upon longitude (primarily Moon positions) are for North America.

Eastern Daylight Time, EDT, is Universal Time (often known as UT, UTC, GMT, or Z time) minus Four hours.

Want to turn into a higher astronomer? Learn your method across the constellations. They’re the important thing to finding every thing fainter and deeper to hunt with binoculars or a telescope.

This is an outside nature pastime. For a straightforward-to-use constellation information masking the entire night sky, use the massive month-to-month map within the heart of every problem of Sky & Telescope, the important journal of astronomy.

Once you get a telescope, to place it to good use you will want a detailed, giant-scale sky atlas (set of charts). The primary normal is the Pocket Sky Atlas (in both the unique or Jumbo Edition), which exhibits stars to magnitude 7.6.

The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and lots of of telescopic galaxies, star clusters, and nebulae amongst them. Shown right here is the Jumbo Edition, in exhausting covers and enlarged for simpler studying outside at night time. Sample chart. More in regards to the current new editions.Next up is the bigger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; practically thrice as many. The subsequent up, as soon as you understand your method round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.0 (stars to magnitude 9.75). And learn easy methods to use sky charts with a telescope.

You’ll additionally need a good deep-sky guidebook, similar to Sky Atlas 2000.0 Companion by Strong and Sinnott, or the larger (and illustrated) Night Sky Observer’s Guide by Kepple and Sanner.

Can a computerized telescope substitute charts? Not for newbies, I do not suppose, and never on mounts and tripods which might be lower than high-high quality mechanically, that means heavy and costly. And as Terence Dickinson and Alan Dyer say of 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 underneath the night sky with yourearbuds in place, take heed to Kelly Beatty’s monthlypodcast 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

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