#astronomy This Week’s Sky at a Look, August 20 – 28 – Sky & Telescope

August 20, 2021 - Comment

RS Ophiuchi fades. On August eighth the well-known recurrent nova RS Ophiuchi lept from its regular magnitude 11.2 to four.eight, dim naked-eye magnitude, after 15 years of simmering quietude. It is fading quickly now, as up to now. See Bob King’s Recurrent Nova RS Ophiuchi Simply Blew its Prime! with finder charts and comparability stars.

RS Ophiuchi fades. On August eighth the well-known recurrent nova RS Ophiuchi lept from its regular magnitude 11.2 to four.eight, dim naked-eye magnitude, after 15 years of simmering quietude. It is fading quickly now, as up to now. See Bob King’s Recurrent Nova RS Ophiuchi Simply Blew its Prime! with finder charts and comparability stars. Ophiuchus is ideally positioned excessive within the night sky.

Nova Cassiopeiae 2021, in the meantime, has bounced round in brightness ever because it erupted from 15th magnitude to 7.7 in March. Amongst its bumps have been brightenings to magnitude 5.5 in early Might and 6.zero round July 27th. As of August 12th it was all the way down to about eight.5. Cas too is excellently positioned within the night sky. Charts and comparability stars.


■ The Moon shines beneath Saturn this night, and Jupiter shines to their left, as proven under.

Moon under Saturn, then Jupiter, Aug 20 and 21, 2021 Because the Moon turns full it hangs beneath Saturn, then Jupiter — which, not coincidentally, are at opposition this month. This scene is in twilight; within the subsequent few hours watch the entire sample climb and switch clockwise.

■ The 2 brightest stars of summer time are Vega, now overhead shortly after dusk, and Arcturus, shining within the west. Draw a line down from Vega to Arcturus. A 3rd of the best way down, the road crosses the dim Keystone of Hercules. Two thirds of the best way down it crosses the dim semicircle of Corona Borealis with its one modestly brilliant star, Alphecca or Gemma.

Additionally: Vega and the Keystone star closest to it type an equilateral triangle with Eltanin to their north, the nostril of Draco the Dragon. Eltanin is the brightest star of Draco’s quadrilateral head; he is eyeing Vega.


■ Now the Moon shines beneath Jupiter, with Saturn to their proper. The Moon is full tonight and tomorrow night time; precise full section happens at 9:02 a.m. tomorrow morning, splitting the date distinction (for night skywatchers within the Americas).

■ As summer time progresses and Arcturus strikes down the western sky, the kite determine of Bootes sprouting up from Arcturus tilts to the precise (relying in your latitude). 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.

The Large Dipper now slants at about the identical top within the northwest, to the Kite’s proper.


■ The Moon once more kinds a giant curving arc with Jupiter and Saturn, however now they’re to the Moon’s proper. The arc spans three fists at arm’s size.


■ By 10 or 11 p.m. the waning Moon is nicely up within the east-southeast. Spot brilliant Jupiter off to its higher proper. They type a virtually equilateral triangle with Fomalhaut, the Autumn Star, rising under Jupiter. How early and low are you able to first see it? Is that this your first sighting of Fomalhaut for this yr’s apparition?


■ One other signal of the advancing season: Cassiopeia is excessive within the northeast, its W sample tilting up. And under it, starry Perseus is reaching up.

The very best a part of Perseus contains the wintry Double Cluster. To search out it, look under the bottom two stars of the Cassiopeia W (they’re the faintest two), by considerably extra that the space between them. You are searching for what looks as if a small spot of enhanced Milky Manner glow. Binoculars or a finderscope will assist you to detect the Double Cluster even via a good quantity of sunshine air pollution. The pair are a glory in a telescope.


■ As August proceeds and nights start to show chilly, the Nice Sq. 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 matches inside it.

From the Sq.’s left nook extends the primary line of the constellation Andromeda: three stars (together with the nook) about as brilliant as these forming the Sq..

This entire big sample was named “the Andromegasus Dipper” by the late Sky & Telescope columnist George Lovi. It is formed type of like a large Little Dipper with an extra-big bowl, and it is presently lifting its contents upward.


■ Low within the northwest or north on the finish of summer time twilights, would you acknowledge noctilucent clouds in the event you noticed them? They’re probably the most astronomical of all cloud varieties, with their excessive altitude and formation on meteoric mud particles. And so they’re pretty uncommon — although changing into extra frequent in recent times because the environment modifications. See Bob King’s article.


■ Every time brilliant Vega crosses nearest your zenith, because it does proper after darkish now, you already know 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-shaped Capricornus down under it to face at their highest due south.

With the passing weeks, Jupiter and Saturn seem ever larger as the celebrities come out.


■ Now that the Moon is out of the night sky, it is prime Milky Manner time. After darkish, the Milky Manner runs from Sagittarius within the south, up and a bit left left throughout Aquila and thru the large Summer time Triangle excessive overhead, and on down via Cassiopeia to Perseus low within the north-northeast.


This Week’s Planet Roundup

Mercury may be very deep within the sundown and fading additional, from magnitude –zero.four to –zero.1 this week. You may need an opportunity at it with binoculars or a wide-field scope. About 15 or 20 minutes after sundown, scan for it simply above your west horizon about 18° (practically two fists at arm’s size) decrease proper of Venus. Good luck.

Venus, good at magnitude –three.9, shines pure white within the west-southwest throughout twilight. It nonetheless units round twilight’s finish.

Jupiter and Saturn shine within the southeast in late twilight and after darkish. They’re magnitudes –2.9 and +zero.2, respectively, in Capricornus.

Jupiter begins the night time lowest. Saturn glows 18° (about two fists) to Jupiter’s higher proper. The pair ranges out round 11 p.m. daylight-saving time. By then they’re about at their highest within the south, at their telescopic finest.

Saturn reached opposition on August 1st, and Jupiter did so on August 19th. So this month they’re at their closest, largest, and brightest of the yr. See “Saturnian Challenges” beginning on web page 52 of the July Sky & Telescope, additionally “Motion at Jupiter” within the August problem, web page 50, and “Canine Days with the Gasoline Giants” on web page 40 of August.

Jupiter’s Nice Pink Spot aspect, imaged on August seventh by Christopher Go together with a 14-inch Schmidt-Cassegrain scope. As is commonplace for planets this can be a stacked-video picture, made from many frames chosen for sharpness after which de-rotated in software program to compensate for the planet’s rotation throughout a protracted video session. On this picture the colours and distinction are enhanced. South is up.

Observe the positive element within the Nice Pink Spot! The South and North Equatorial Belts have principally diminished to slim dark-reddish strains. Darkish crimson spots proceed simply north of the NEB. A lot of the Equatorial Zone continues pale yellow-tan.

Saturn on July 25, 2021Saturn on July 25. North is up. This beautiful stacked-video picture exhibits element within the broad A Ring, in addition to the skinny Encke Hole simply contained in the outer fringe of the outer B Ring. Saturn’s Equatorial Zone is brilliant as typical, and its North Equatorial Belt is distinct. The slim darkish band seemingly on the opposite aspect of the equatorial Zone is definitely the dim, inside C ring. Agapios Elia of Nicosia, Cyprus, took video throughout 45 minutes on July 25th utilizing a 9.25-inch Schmidt-Cassegrain scope. He de-rotated the globe throughout processing after which stacked massive numbers of the of finest frames.

Uranus (magnitude 5.7, in Aries) and Neptune (magnitude 7.eight, on the Aquarius-Pisces border) are excessive within the southeast to south within the early-morning hours.

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.

Jap Daylight Time, EDT, is Common Time minus four hours. Common Time is often known as UT, UTC, GMT, or Z time. To turn into extra knowledgeable about time techniques than 99% of the folks you will ever meet, see our compact article Time and the Novice Astronomer.

Need to turn into a greater astronomer? Be taught your manner across the constellations. They’re the important thing to finding all the things fainter and deeper to hunt with binoculars or a telescope.

That is an out of doors nature passion. For an easy-to-use constellation information masking the entire night sky, use the large month-to-month map within the heart of every problem of Sky & Telescope, the important journal of astronomy.

When you get a telescope, to place it to good use you will want an in depth, large-scale sky atlas (set of charts). The essential commonplace is the Pocket Sky Atlas (in both the unique or Jumbo Version), which exhibits stars to magnitude 7.6.

Pocket Sky Atlas cover, Jumbo editionThe Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and tons of of telescopic galaxies, star clusters, and nebulae amongst them. Proven right here is the Jumbo Version, which is in onerous covers and enlarged for simpler studying open air by crimson flashlight. Pattern charts. Extra in regards to the present editions.

Subsequent up is the bigger and deeper Sky Atlas 2000.zero, plotting stars to magnitude eight.5; practically 3 times as many. The following up, as soon as you already know your manner round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.zero (stars to magnitude 9.75). And make sure to learn the best way to use sky charts with a telescope.

You may additionally need a good deep-sky guidebook, akin to Sky Atlas 2000.zero Companion by Robust and Sinnott, or the larger (and illustrated) Evening Sky Observer’s Information by Kepple and Sanner.

Can a computerized telescope exchange charts? Not for novices, I do not assume, and never on mounts and tripods which might be lower than top-quality mechanically, which means heavy and costly. And as Terence Dickinson and Alan Dyer say of their Yard Astronomer’s Information, “A full appreciation of the universe can not come with out creating the abilities to search out issues within the sky and understanding how the sky works. This information comes solely by spending time beneath the celebrities with star maps in hand.”

Audio sky tour. Out beneath the night sky together with your
earbuds in place, hearken to Kelly Beatty’s month-to-month
podcast tour of the heavens above. It is free.

“The risks of not considering clearly are a lot better now than ever earlier than. It is not that there is one thing new in our mind-set, it is that credulous and confused considering could be rather more deadly in methods it was by no means earlier than.”
            — Carl Sagan, 1996

“Information are cussed issues.”
            — John Adams, 1770


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