#astronomy This Week’s Sky at a Look, September three – 11 – Sky & Telescope

September 3, 2021 - Comment

The bursting stars RS Ophiuchi and Nova Cassiopeiae 2021 proceed to hover round magnitude 8½. FRIDAY, SEPTEMBER three ■ Earlier than moonlight returns to the night sky subsequent week, hint out the Milky Means arching from horizon to zenith to horizon after dusk is full. Even via a good quantity of sunshine air pollution you’ll

The bursting stars RS Ophiuchi and Nova Cassiopeiae 2021 proceed to hover round magnitude 8½.


■ Earlier than moonlight returns to the night sky subsequent week, hint out the Milky Means arching from horizon to zenith to horizon after dusk is full. Even via a good quantity of sunshine air pollution you’ll be able to see refined traces of it. The Milky Means runs from the low south-southwest (between Sagittarius and the tail of Scorpius) up via Aquila after which Cygnus excessive overhead, on down via Cepheus and Cassiopeia to Perseus low within the north-northeast.

Cygnus sports activities the Cygnus Star Cloud, one of many Milky Means’s richest areas. Discover right here in depth with binoculars or a small scope utilizing Matt Wedel’s “Touring Cygnus with Binoculars” within the September Sky & Telescope beginning on web page 34.

■ Within the dawns of Saturday and Sunday, spot the skinny morning Moon waning away as proven under.

The waning crescent Moon steps down within the east-northeast within the dawns of Saturday and Sunday September 4th and fifth. On the sixth, shortly earlier than dawn, the Moon will nearly definitely be too low and slim to detect even with binoculars or a telescope, even when the air could be very clear; the Moon will then be solely about 16 hours from new for East-Coast crescent hunters, and a mere 13 hours from new within the Pacific time zone.

Need to give this actually main problem a strive? And possibly set your thin-Moon lifetime file sighting? Learn how in “Searching for Very Previous Lunar Crescents” within the September Sky & Telescope beginning on web page 49.


■ In early twilight, search for little Spica decrease left of Venus by 1.eight°. It is only one/100 as vivid. Tomorrow they will be 1.6° aside.


■ Now in early twilight, search for Spica below Venus by 1.6° as proven under. And, are you able to handle to catch Mercury 15° (a couple of fist and a half) to their decrease proper?

Spica, a finger-width under Venus this night, is only one% as vivid. Nicely at the least it twinkles.

In actuality, Spica is sort of 1,000 occasions bigger than Venus in bodily diameter. And with its blinding blue-white temperature, it emits 5 trillion occasions extra gentle than the daylight that Venus displays. However at a distance of 260 light-years, Spica is 16 million occasions farther away. Area is huge.

■ As autumn approaches, Fomalhaut, the Autumn Star, makes its look above the southeast horizon in mid- to late night. Its rising time will rely on the place you reside. However by about 10 p.m. you should not have any hassle recognizing it low within the southeast; simply discover an open view in that route. This season Fomalhaut is simpler to find than normal: Look about two fists under Jupiter and a little bit left.

■ New Moon (actual at eight:52 p.m. EDT).


■ By 10 p.m. two of the best-known deep-sky objects, the Double Cluster in Perseus and the Nice Andromeda Galaxy M31, are in excessive view within the east. Do you know they’re solely 22° aside? They’re each cataloged as 4th magnitude however to the bare eye they appear reasonably completely different from one another, the extra so the darker your sky. See for your self; they’re plotted on the all-sky constellation map within the heart of the September Sky & Telescope, which must be all of the map you must establish their places. They’re under Cassiopeia and farther to Cassiopeia’s proper, respectively. Sky too vivid? Use binoculars!

The 2 clusters of the Double Cluster (NGC 869 and NGC 884) are at very comparable distances about 7,600 light-years away. M31, at 2.5 million light-years, is about 330 occasions as far.


■ Early in twilight use the low, skinny Moon to information you down towards Mercury, as proven under. They’re going to be about 5° aside. Binoculars assist.

Reentering the night sky to begin a brand new lunation, the skinny Moon hangs higher proper of Mercury, then higher proper of Venus, low within the west-southwestern twilight. Little Spica switches place with respect to them from the eighth to the ninth. (The Moon is drawn thrice its precise obvious dimension.)


■ Now catch the extra apparent crescent Moon paired with white-light Venus low within the west-southwest in twilight, as proven above. They’re going to be four° aside for North America. Are you able to make out Spica under them?


■ The 2 brightest stars (not planets) of September evenings are Vega excessive overhead and Arcturus within the west, each magnitude zero.

Draw a line from Vega right down to Arcturus. A 3rd of the best way down you cross the dim Keystone of Hercules. Two thirds of the best way you cross the dim semicircle of Corona Borealis with its one modestly vivid star: Alphecca, the gem of the crown.


■ Look left of the thick crescent Moon for the top stars of Scorpius, then orange Antares. Midway between the Moon and Antares (for the Americas) is the brightest of the top stars, the long-term eruptive variable Delta Scorpii. It has been holding pretty regular at magnitude 1.eight since 2010.


This Week’s Planet Roundup

Mercury (magnitude zero.zero) could be very deep down within the sundown, 15° decrease proper of Venus 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 horizon due west. Good luck.

Venus, sensible at magnitude –four.zero, shines within the west-southwest throughout twilight. It nonetheless units round twilight’s finish.

Jupiter and Saturn shine within the southeast to south these evenings. They’re magnitudes –2.eight and +zero.three, respectively, in dim Capricornus.

Jupiter begins the night as barely the decrease of the 2. lowest. Saturn glows 17° (nearly two fists) to Jupiter’s higher proper. They degree out round 10 p.m. daylight-saving time. By then they’re about at their highest within the south, at their telescopic greatest. See “Saturnian Challenges” beginning on web page 52 of the July Sky & Telescope, additionally “Canine Days with the Gasoline Giants” on web page 40 of August.

Three satellites on Jupiter, two shadow transits, and extra! “Immediately we had a grand slam occasion,” wrote Christopher Go from the Philippines on August 15th. “A really uncommon triple transit on Jupiter with the moons Callisto, Ganymede and Europa in transit. As a bonus, eclipsed Io was seen simply earlier than it went behind Jupiter. After the triple transit there was a really uncommon occasion when Ganymede occulted Europa adopted by Ganymede eclipsing Europa! Seeing the shadow of Ganymede over Europa was surreal!” Within the photos right here, north is up.

However the easiest way to comply with the sequence of occasions is by video! The Washington Publish put all of it collectively together with a step-by-step information: Watch this ‘surreal’ Jupiter eclipse that you simply most likely missed.

Saturn on July 25, 2021Saturn on July 25th. North is up. This beautiful stacked-video picture exhibits element within the broad B Ring, in addition to the skinny Encke Hole simply contained in the outer fringe of the outer A Ring. Saturn’s Equatorial Zone is vivid as normal, and its North Equatorial Belt is distinct. The slender darkish band seemingly on the opposite facet of the Equatorial Zone is definitely the dim, internal 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 greatest frames.

Uranus (magnitude 5.7, in Aries) will get excessive within the east after midnight.

Neptune (magnitude 7.eight, on the Aquarius-Pisces border) is pretty excessive within the southeast as early as 10 p.m.

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 referred to as UT, UTC, GMT, or Z time. To develop into extra professional about time techniques than 99% of the individuals you may ever meet, see our compact article Time and the Novice Astronomer.

Need to develop into a greater astronomer? Study your manner 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 outside nature passion. For an easy-to-use constellation information protecting 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.

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 arduous covers and enlarged for simpler studying outdoor by crimson flashlight. Pattern charts. Extra concerning 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 manner round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.zero (stars to magnitude 9.75). And you should definitely learn use sky charts with a telescope.

You will additionally need a good deep-sky guidebook, akin to the large Night time Sky Observer’s Information by Kepple and Sanner.

Can a computerized telescope exchange charts? Not for learners, I do not suppose, and never on mounts and tripods which can be 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 creating the talents to search out issues within the sky and understanding how the sky works. This information comes solely by spending time below the celebrities with star maps in hand.”

Audio sky tour. Out below the night sky along with your
earbuds in place, take heed to Kelly Beatty’s month-to-month
podcast tour of the heavens above. It is free.

“The hazards of not pondering 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 pondering may 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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