This Week’s Sky at a Glance, September 3 – 11

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


FRIDAY, SEPTEMBER 3

■ Before moonlight returns to the night sky subsequent week, hint out the Milky Way arching from horizon to zenith to horizon after dusk is full. Even by a truthful quantity of sunshine air pollution you possibly can see delicate traces of it. The Milky Way runs from the low south-southwest (between Sagittarius and the tail of Scorpius) up by Aquila after which Cygnus excessive overhead, on down by Cepheus and Cassiopeia to Perseus low within the north-northeast.

Cygnus sports activities the Cygnus Star Cloud, one of many Milky Way’s richest areas. Explore 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.

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

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 actually 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.

Want to present this actually main problem a attempt? And possibly set your thin-Moon lifetime document sighting? Read how in “Seeking Very Old Lunar Crescents” within the September Sky & Telescope beginning on web page 49.

SATURDAY, SEPTEMBER 4

■ In early twilight, search for little Spica decrease left of Venus by 1.8°. It’s only one/100 as brilliant. Tomorrow they’re going to be 1.6° aside.

SUNDAY, SEPTEMBER 5

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

Spica, a finger-width beneath Venus this night, is only one% as brilliant. Well at least it twinkles.

In actuality, Spica is almost 1,000 instances bigger than Venus in bodily diameter. And with its blinding blue-white temperature, it emits 5 trillion instances extra mild than the daylight that Venus displays. But at a distance of 260 light-years, Spica is 16 million instances farther away. Space 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. But by about 10 p.m. you shouldn’t have any bother recognizing it low within the southeast; simply discover an open view in that route. This season Fomalhaut is simpler to find than standard: Look about two fists beneath Jupiter and a little left.

■ New Moon (actual at 8:52 p.m. EDT).

TUESDAY, SEPTEMBER 7

■ By 10 p.m. two of the best-known deep-sky objects, the Double Cluster in Perseus and the Great Andromeda Galaxy M31, are in excessive view within the east. Did you recognize they’re solely 22° aside? They’re each cataloged as 4th magnitude however to the bare eye they give the impression of being quite 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 it is advisable determine their areas. They’re beneath Cassiopeia and farther to Cassiopeia’s proper, respectively. Sky too brilliant? Use binoculars!

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

WEDNESDAY, SEPTEMBER 8

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

Reentering the night sky to start out a 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.)

THURSDAY, SEPTEMBER 9

■ Now catch the extra apparent crescent Moon paired with white-light Venus low within the west-southwest in twilight, as proven above. They’ll be 4° aside for North America. Can you make out Spica beneath them?

FRIDAY, SEPTEMBER 10

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

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

SATURDAY, SEPTEMBER 11

■ Look left of the thick crescent Moon for the pinnacle stars of Scorpius, then orange Antares. Halfway between the Moon and Antares (for the Americas) is the brightest of the pinnacle stars, the long-term eruptive variable Delta Scorpii. It’s been holding pretty regular at magnitude 1.8 since 2010.

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This Week’s Planet Roundup

Mercury (magnitude 0.0) could be very deep down within the sundown, 15° decrease proper of Venus this week. You would possibly have a likelihood 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 –4.0, 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 –2.8 and +0.3, 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 “Dog Days with the Gas Giants” on web page 40 of August.

Three satellites on Jupiter, two shadow transits, and extra! “Today we had a grand slam event,” wrote Christopher Go from the Philippines on August fifteenth. “A very rare triple transit on Jupiter with the moons Callisto, Ganymede and Europa in transit. As a bonus, a partially eclipsed Io was seen just before it went behind Jupiter. After the triple transit there was a very rare event when Ganymede occulted Europa followed by Ganymede eclipsing Europa! Seeing the shadow of Ganymede over Europa was surreal!” In the photographs right here, north is up.

But one of the best way to observe the sequence of occasions is by video! The Washington Post put all of it collectively together with a step-by-step information: Watch this ‘surreal’ Jupiter eclipse that you probably missed.

(*3*)
Saturn on July twenty fifth. North is up. This beautiful stacked-video picture exhibits element within the broad B Ring, in addition to the skinny Encke Gap simply contained in the outer fringe of the outer A Ring. Saturn’s Equatorial Zone is brilliant as standard, and its North Equatorial Belt is distinct. The slim darkish band seemingly on the opposite aspect of the Equatorial Zone is definitely the dim, internal C ring. Agapios Elia of Nicosia, Cyprus, took video throughout 45 minutes on July twenty fifth 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 7.8, at 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.

Eastern Daylight Time, EDT, is Universal Time minus 4 hours. Universal Time is also called UT, UTC, GMT, or Z time. To develop into extra professional about time programs than 99% of the individuals you may ever meet, see our compact article Time and the Amateur Astronomer.


Want to develop into a higher astronomer? Learn your way 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 out of doors nature interest. For an easy-to-use constellation information protecting the entire night sky, use the massive month-to-month map within the heart of every concern of Sky & Telescope, the important journal of astronomy.

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

Pocket Sky Atlas cover, Jumbo edition
The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and tons of of telescopic galaxies, star clusters, and nebulae amongst them. Shown right here is the Jumbo Edition, which is in onerous covers and enlarged for simpler studying open air by red flashlight. Sample charts. More about the current 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 recognize your way round, are the even bigger Interstellarum atlas (stars to magnitude 9.5) or Uranometria 2000.0 (stars to magnitude 9.75). And you’ll want to learn how to use sky charts with a telescope.

You’ll additionally need a good deep-sky guidebook, corresponding to the massive Night Sky Observer’s Guide by Kepple and Sanner.

Can a computerized telescope exchange charts? Not for freshmen, 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 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 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’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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