#astronomy This Week’s Sky at a Look, August 13 – 21 – Sky & Telescope

August 14, 2021 - Comment

RS Ophiuchi erupts. For the primary time since 2006, on August eighth the well-known recurrent nova RS Ophiuchi lept from its regular magnitude 11.2 to four.eight, dim naked-eye magnitude. Within the first week after its previous outbursts RS Oph has pale easily by about two magnitudes, then it declines extra slowly all the way down

RS Ophiuchi erupts. For the primary time since 2006, on August eighth the well-known recurrent nova RS Ophiuchi lept from its regular magnitude 11.2 to four.eight, dim naked-eye magnitude. Within the first week after its previous outbursts RS Oph has pale easily by about two magnitudes, then it declines extra slowly all the way down to regular. See Bob King’s Recurrent Nova RS Ophiuchi Simply Blew its High! with finder charts and comparability stars. Ophiuchus is ideally positioned excessive within the night sky.

Nova Cas fades. Nova Cassiopeiae 2021 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. Charts and comparability stars. Cas too is excellently positioned within the night sky.


■ A twilight problem: as twilight fades, study Venus with binoculars or a small telescope. Chances are you’ll discover a tiny spark barely zero.1° from it (under it as seen from mid- North America). That is Beta Virginis. At visible magnitude three.6, Beta Vir is 1,000 instances fainter than Venus.

■ A lot simpler: Search for 1st-magnitude Spica decrease proper of the Moon, by rather less than a fist at arm’s size. A lot increased to their higher proper shines brighter Arcturus.


■ The brightest star excessive within the southeast these evenings is Altair, with little orange Tarazed above it by a finger-width at arm’s size.


■ First-quarter Moon (precise at 11:20 a.m. EDT). This night the Moon shines close to the pinnacle of Scorpius. Look left of the Moon for the roughly vertical row of Beta, Delta, and fainter Pi Scorpii, between the Moon and Antares. Delta’s correct title, Dschubba, is from the Arabic for “Brow” of the scorpion.

Delta is the brightest of the three. It is an irregular variable star: a fast-rotating blue subgiant throwing off luminous gasoline from its equator. It has a smaller orbiting companion that appears to set off extra such exercise at 10.5-year intervals. Lengthy presumed to be secure, Delta unexpectedly doubled in brightness in the summertime of 2000 and has remained practically that vivid, with fluctuations, for most of the years since.

Astronomers are ready to see whether or not it’ll show one other flareup quickly, when the companion makes its third move by the first star for the reason that instability began in 2000.


■ Now the Moon shines higher left of Antares, as proven under (for North America).

Proper after first quarter the Moon shines close to Antares, then excessive over the Cat’s Eyes.

■ Concerning the Moon in your scope, have you ever ever made a examine of lunar craters’ central peaks? Discover them and the physics behind them with Chuck Wooden’s “Hills within the Center” within the August Sky & Telescope, web page 52.


■ After dusk, look far under the Moon for the Cat’s Eyes within the tail of Scorpius (as proven above for mid-twilight). These are Lambda and fainter Upsilon Scorpii, zero.6° aside and canted at an angle; the cat is tilting its head to the precise. And the cat has a bleary eye; Upsilon is fainter than Lambda (they’re magnitudes 2.6 and 1.6). Each are blue-white giants, 500 and 700 mild years away, respectively. Sure, the fainter one is the nearer one.


■ Approach, approach, approach down low within the vivid afterglow of sundown, Mercury and Mars are in conjunction solely zero.1° aside (for North America). About 15 or 20 minutes after sundown, use binoculars or a small telescope to attempt to decide up Mercury a number of levels above the horizon. It is a hint to the precise of due west, far decrease proper of Venus. You have received a reasonably good probability; Mercury is at the moment magnitude –zero.5. Mars is one other story; at magnitude +1.eight it is solely an eighth as vivid. Good luck with that. . . .

■ After darkish, look above the waxing gibbous Moon for 2nd-magnitude Sigma Sagittarii (Nunki). It is the brightest star within the deal with of the Sagittarius Teapot.

The Moon’s darkish limb occults Nunki for Florida and different components of the southernmost US, Mexico, Central America, and the Caribbean; map and timetables.


■ The Moon kinds an awesome, curving arc with Saturn and brighter Jupiter, that are to its left.

■ Jupiter is at opposition, reverse the Solar as seen from Earth. Amongst different issues, this implies the tiny black shadows of Jupiter’s moons cross the face of the planet very near the moons themselves. Each the shadows and the moons enter and exit Jupiter’s edges just some minutes from one another. See timetables for all these occasions (in addition to for when Jupiter’s Nice Pink Spot transits the planet’s central meridian) within the August Sky & Telescope, pages 51-52.


■ The intense 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 the road crosses the dim semicircle of Corona Borealis with its one modestly vivid star, Alphecca or Gemma.

Vega and the Keystone’s 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.

■ As summer time progresses and Arcturus strikes down the western sky, the kite determine of Bootes that sprouts up from Arcturus tilts to the precise (relying in your latitude). The kite is slim, barely bent with its prime 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 Massive Dipper now slants at about the identical top within the northwest, to the Kite’s proper.


This Week’s Planet Roundup

Mercury and Mars are very deep within the sundown. You might need an opportunity for Mercury. About 15 or 20 minutes after sundown, search for it with binoculars or a wide-field scope simply above your west horizon about 20° (two fists at arm’s size) decrease proper of Venus. Mercury dims from magnitude –zero.eight to –zero.four this week, so earlier within the week is best.

A lot-fainter Mars is in Mercury’s neighborhood, passing it by a mere zero.1° at their conjunction on the 18th (as seen in twilight for the Americas). However since Mars is simply magnitude 1.eight, you in all probability have zero probability. Show me flawed?

Venus, sensible at magnitude –three.9, shines pure white within the west throughout twilight. It 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 or very close to Capricornus.

Jupiter begins the night time lowest. Saturn glows 19° (about two fists) to Jupiter’s higher proper. The pair ranges out round 11 or midnight daylight-saving time. By then they’re about at their highest within the south, at their telescopic finest.

Saturn reached opposition on August 1st. Jupiter does so on August 19th. So this month they’re at their closest, greatest, 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 situation, web page 50, and “Canine Days with the Gasoline Giants” on web page 40 of August.

Jupiter’s Nice Pink Spot facet, imaged on August seventh by Christopher Go along with a 14-inch Schmidt-Cassegrain scope. This can be a stacked-video picture, de-rotated throughout frames and with colours and distinction boosted. South is up. Word the high-quality element within the Nice Pink Spot! The South and North Equatorial Belts have largely diminished to slim dark-reddish traces. Small, dark-red 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 vivid as common, and the darker North Equatorial Belt is kind of distinct. Agapios Elia of Nicosia, Cyprus, took video throughout 45 minutes on July 25th utilizing a 9.25-inch Schmidt-Cassegrain scope. He stacked massive numbers of one of the best frames after de-rotating the globe throughout processing.

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 pre-dawn 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 rely on longitude (primarily Moon positions) are for North America.

Jap Daylight Time, EDT, is Common Time minus four hours. Common Time is also called UT, UTC, GMT, or Z time. To grow to be extra knowledgeable about time techniques than 99% of the folks you may ever meet, see our compact article Time and the Beginner Astronomer.

Need to grow to be a greater astronomer? Be taught your approach across the constellations. They’re the important thing to finding every little thing 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 massive month-to-month map within the middle of every situation of Sky & Telescope, the important journal of astronomy.

When you get a telescope, to place it to good use you may want an in depth, large-scale sky atlas (set of charts). The essential normal 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 lots of of telescopic galaxies, star clusters, and nebulae amongst them. Proven right here is the Jumbo Version, which is in exhausting covers and enlarged for simpler studying open air by pink 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 thrice as many. The subsequent up, as soon as you understand your approach round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.zero (stars to magnitude 9.75). And make sure you learn the right way to use sky charts with a telescope.

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

Can a computerized telescope substitute charts? Not for learners, I do not assume, and never on mounts and tripods which are lower than top-quality mechanically, that 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’t come with out growing the abilities to search out issues within the sky and understanding how the sky works. This information comes solely by spending time beneath the celebs with star maps in hand.”

Audio sky tour. Out beneath the night sky along 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 may be far more deadly in methods it was by no means earlier than.”
            — Carl Sagan, 1996

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


Supply hyperlink


Comments are disabled for this post.