This Week’s Sky at a Glance, August 21 – 29 – Sky & Telescope


■ Spot the crescent Moon low within the west-southwest in twilight. Look to its left by about 16° for Spica twinkling into view, as proven beneath. Spica, often thought-about 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 instances 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 in these scenes is all the time drawn about 3 times its precise obvious dimension, so do not choose the celebrities’ distances from the Moon by the dimensions of the crescents right here. ■ Double shadow transit on Jupiter. For telescope customers in western North American late Friday night time, Io and Ganymede are each casting their tiny black shadows onto the face of Jupiter from 11:32 p.m. to 1:20 a.m. Pacific Daylight Time.


■ Look beneath the Moon at dusk for Spica, as proven above. They’re 5° or 6° aside at nightfall in North America.

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


■ Whenever vibrant Vega crosses nearest your zenith, because it does quickly after darkish now, you recognize 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.


■ As nightfall turns into night time, look left of the Moon for the close to-vertical row of stars marking the top of Scorpius. Antares and its two outrigger stars shine a little farther left. And see tomorrow’s entry in regards to the telescopic double stars awaiting you right here.

■ 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 simply 17 gentle-years away. Tarazed (Gamma Aquilae) is a purple big about 400 gentle-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.


■ First-quarter Moon (actual at 1:58 p.m. EDT). Come dusk, the Moon shines simply above Antares and the top of Scorpius. As quickly as you are achieved with the Moon in your scope, take a look at the double stars Beta Scorpii (the highest of the row of three head stars) and fainter Nu Scorpii proper close to it. Beta this night is about 4° proper of the Moon, simple to identify with a complete magnitude of two.6. It’s a advantageous double for any telescope: separation 13 arcseconds, magnitudes 2.Eight and 5.0.Upper left of Beta by 1.6° is Nu Scorpii, separation 41 arcseconds, magnitudes 3.Eight and 6.5 . In reality it is a telescopic triple. High energy in good seeing reveals Nu’s brighter part itself to be a shut binary, separation 2 arcseconds, magnitudes 4.Zero and 5.3, aligned nearly north-south.


■ This night proper after nightfall, the Saturn-Jupiter line factors straight at the Moon to their left. Lower left of the Moon is Antares.And look down beneath the Moon, by about 14° and simply a bit left, for the star pair often known as the Cat’s Eyes: Lambda and Upsilon Scorpii within the Scorpion’s tail. They’re 0.6° aside and canted at an angle. They’re unequal (magnitudes 1.6 and a couple of.7); the cat is winking. The brighter one, on the higher left, is Lambda. Both are blue-white supergiants, 700 and 500 gentle years away respectively.


■ The waxing gibbous Moon shines due south at the tip of twilight, nonetheless to the suitable of Jupiter and Saturn and nearly in step with them. The Moon is poised simply above the lid of the Sagittarius Teapot. Can you may see the Teapot stars by the moonlight? If not binoculars do the trick, however solely a smallish a part of the Teapot will match of their view at as soon as.

■ Ceres, the primary asteroid found (in 1801) is at opposition tonight in southern Aquarius at magnitude 7.7. It’s about 6° north-northeast of 1st-magnitude Fomalhaut, your simple place to begin for a cautious star hop late these nights to determine Ceres utilizing the finder chart within the August Sky & Telescope, web page 50. Ceres stays about that vibrant all this week and subsequent because it creeps alongside.


■ Jupiter shines simply a couple levels above the gibbous Moon this night for North America; see the twilight view beneath. To their left, Saturn waits its flip.

The waxing gibbous Moon passes beneath Jupiter and Saturn.SATURDAY, AUGUST 29

■ Now the eastward-marching Moon shines nearer to Saturn than to Jupiter, as proven above. The three are, after all, at very totally different distances: The Moon is 1.Three gentle-seconds from you, Jupiter is at present 37 gentle minutes distant, and Saturn is 77 gentle-minutes.


This Week’s Planet Roundup

Have you caught Venus at daybreak but? It’ll be there for the remainder of 2020, however decrease every month.Mercury is hidden within the glare of the Sun.

Venus (magnitude –4.3, in Gemini) rises in deep darkness about two hours earlier than daybreak begins, a bizarre UFO of a factor within the east-northeast. By the time daybreak will get underneath method, Venus blazes brightly excessive within the east as proven above.

Pollux and Castor are at present left if it, and Procyon is to its decrease proper, as proven. Spot Orion farther to Venus’s proper. High above or higher left of Venus is vibrant Capella.

In a telescope Venus is simply previous dichotomy: barely greater than half lit.

Mars rises within the east lower than an hour after the tip of twilight. It emerges vibrant (magnitude –1.6) and strongly orange like a far-off bonfire. Where will it come up? Watch the horizon far beneath the Great Square of Pegasus.Mars climbs increased all by the night time. By the start of 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 17½ to 18½ arcseconds in obvious diameter. That’s already larger than it seems at many oppositions, however we’re nonetheless approaching Mars as Earth speeds alongside our sooner orbit across the Sun. When we catch as much as and go Mars at opposition in early October, it is going to seem 22.6 arcseconds huge and can shine at a Jupiter-bright magnitude –2.6.

Mars remains to be gibbous, 90% sunlit. Look for its white South Polar cap, doable clouds particularly close to the limb, and subtler darkish floor markings. To get a map of the aspect going through us at the date and time you may observe, use our Mars Profiler. The map there may be sq.; keep in mind to mentally wrap it onto the aspect of a globe. (Features close to the map’s edges change 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 tremendously with the advance of summer time in Mars’s southern hemisphere. The giant, darkish spherical function close to the terminator higher left of heart is Solis Lacus and its environment, “the Eye of Mars.” The giant, wavy darkish band working towards the suitable limb is Mare Sirenum. In from the underside proper limb is low-distinction Olympus Mons. 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 +0.3, respectively) shine within the south-southeast in twilight. They’re highest within the south, for sharpest telescopic viewing, shortly after darkish. Jupiter is the brightest; Saturn is 8° to its left.They’re completely horizontal proper across the finish of twilight. Lower proper of Jupiter after darkish is the deal with of the Sagittarius Teapot.Follow the telescopic interaction of Jupiter with its moons and their shadows, and discover all of the transit instances 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 utilized to 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 the barest 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, east of Mars.

Neptune (magnitude 7.8, in Aquarius) is increased within the southeast by that point. 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 rely 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 change 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 passion. For a straightforward-to-use constellation information overlaying the entire night sky, use the large month-to-month map within the heart of every difficulty of Sky & Telescope, the important journal of astronomy.

Once you get a telescope, to place it to good use you may want a detailed, giant-scale sky atlas (set of charts). The primary commonplace 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 a whole bunch of telescopic galaxies, star clusters, and nebulae amongst them. Shown right here is the Jumbo Edition, in exhausting covers and enlarged for simpler studying outdoor 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 3 times as many. The subsequent up, as soon as you recognize 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 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 novices, I do not suppose, and never on mounts and tripods which are 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, hearken 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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