The Sky This Week from Aug. 20 to Sept. 5: Saturn’s time to shine

Sky This Week is delivered to you partially by Celestron.

Friday, August 29
The waxing Moon lies in southern Libra tonight. Our satellite tv for pc is rapidly approaching Scorpius, the place it can meet the Scorpion’s brightest star in just some days. 

High within the southeast within the few hours after sundown is the small constellation Sagitta the Arrow. It lies above the bigger, extra simply recognizable constellation Aquila the Eagle, which is marked by the brilliant star Altair (a part of the Summer Triangle). 

Tonight, we’re in search of the globular cluster M71, an Eighth-magnitude ball of historic stars that sits roughly midway between Delta (δ) and Gamma (γ) Sagittae. Around 9:30 P.M. native daylight time, magnitude 3.8 Delta lies some 9.7° above magnitude 0.8 Altair. Magnitude 3.5 Gamma Sge lies simply to Delta’s higher left, about 3° away. M71 sits halfway between them, overlaying about 7’ on the sky. The cluster’s vivid central core is straightforward to identify with binoculars or a small scope, whereas increased magnification (or bigger scopes) will reveal an rising variety of stars. M71 is a comparatively loosely packed cluster, so be aware how its look differs from denser objects, resembling M13 in Hercules. 

M71 lies about 13,000 light-years away, and its vivid core covers a real diameter in house of about 24 light-years.

Sunrise: 6:25 A.M.
Sunset: 7:36 P.M.
Moonrise: 12:53 P.M.
Moonset: 10:23 P.M.
Moon Phase: Waxing crescent (36%)
*Times for dawn, sundown, moonrise, and moonset are given in native time from 40° N 90° W. The Moon’s illumination is given at 12 P.M. native time from the identical location.

Saturday, August 30
Saturn’s moon Iapetus reaches biggest western elongation at present, now positioned 9.5’ west of the ringed planet. Iapetus has two vastly completely different hemispheres, one gentle and one darkish. As the moon orbits Saturn, it slowly rotates in order that one after which the opposite facet faces us, with its brightness various vastly relying on which area is pointed at Earth. At western elongation the icy, brighter facet of Iapetus is turned towards us, bringing the moon’s brightness as much as Tenth magnitude, in keeping with a few of Saturn’s different moons (Rhea, Tethys, and Dione). Titan, at mid-Eighth-magnitude, continues to be brightest — we’ll make certain to find it tonight, too. 

Saturn is rising within the east about an hour after sundown. Give it a little bit time to climb out of the horizon haze after which level your scope at it late this night or in a single day into the early-morning hours. Around 11 P.M. native daylight time, it’s reached 25° in altitude within the east, hanging beneath the Circlet of Pisces and shining because the brightest level of sunshine in that area of the sky. 

Through a telescope, you’ll spot Titan some 3’ east of Saturn; once more, it’s the brightest of the planet’s moons. Then look far — a full 9.5’! — west of Saturn to identify Tenth-magnitude Iapetus. Much nearer in, round midnight EST you’ll additionally see Tethys simply off the japanese finish of the rings, with Rhea simply north of the rings additionally to the planet’s east. Dione lies west of the western fringe of the rings, with a lot fainter (twelfth magnitude) Enceladus between it and the sting of the rings. You could not be capable to spot Enceladus, so don’t be stunned should you can’t make it out. 

There’s extra happening across the ringed planet this week — and all subsequent month, because it approaches opposition September 21 — so keep tuned. We’ll be again on this area of the sky quickly! 

Sunrise: 6:26 A.M.
Sunset: 7:34 P.M.
Moonrise: 1:56 P.M.
Moonset: 10:58 P.M.
Moon Phase: Waxing crescent (45%)

Sunday, August 31
Bright Venus hangs close to the stunning Beehive Cluster (M44) in Cancer this morning. Both rise greater than two hours earlier than the Sun and attain practically 20° excessive within the east an hour earlier than dawn. Venus shines at magnitude –3.9, a blazing beacon simply 1.4° southwest (to the higher proper) of the Beehive. 

At magnitude 3.1, M44 is seen to the bare eye, though viewing it this fashion whereas it’s low within the sky and twilight is approaching will probably be troublesome. Instead, attempt for the brilliant, scattered stars of the Beehive with binoculars or your telescope’s finder scope. A small scope with a large area of view can even reveal a number of of its suns, and even catch Venus throughout the view.

Through a telescope, Venus reveals off a 12”-wide gibbous disk that’s 84 % lit. What you’re seeing is daylight reflecting off the venusian cloud tops, because the planet is swathed in a thick blanket of carbon dioxide that each hides the floor from view and creates a robust greenhouse impact that heats the planet to some 870 levels Fahrenheit (465 levels Celsius).

First Quarter Moon happens at 2:25 A.M. EDT this morning. The Moon then passes 0.7° south of Antares at 7 A.M. EDT, though neither is seen at the moment. You can catch the pairing within the southern sky this night, with the waxing Moon now sitting about 7.5° to the left (southeast) of ruddy Antares within the darkening twilight. They stay above the horizon for just a few hours, setting round 11:30 P.M. native time. 

Sunrise: 6:27 A.M.
Sunset: 7:33 P.M.
Moonrise: 2:57 P.M.
Moonset: 11:41 P.M.
Moon Phase: Waxing gibbous (54%)

Monday, September 1
Cepheid variables are a number of the most well-known variable stars within the sky, chargeable for serving to astronomers precisely measure cosmic distances and famously clueing Edwin Hubble in to the truth that the Andromeda Galaxy was far past the Milky Way. So, tonight let’s start September by discovering the Cepheid variable that began all of it: Delta Cephei, the archetype Cepheid variable. 

Related: The star that modified the cosmos

If you know the way stellar names work, you’ll already know the place to search out this star — it’s within the constellation Cepheus. The King lies excessive within the north after darkish right now of yr, his house-shaped define showing upside-down early within the night, then slowly rotating onto its facet because the hours progress. Cepheus is a circumpolar constellation, which means it seems to circle the North Celestial Pole (and the North Star, Polaris) moderately than rise within the east and set within the west. 

Two hours after sundown, Cepheus is 50° excessive within the north, standing on the highest of its peaked roof, marked by magnitude 3.2 Gamma Cep. The two stars marking the eaves of the home (on the prime of its sq. form when rightside-up) are above Gamma right now — they’re magnitude 3.2 Beta (β) and magnitude 3.5 Iota (ι) Cep. Above Beta is magnitude 2.5 Alpha (α) Cep, and above Iota is magnitude 3.4 Zeta (ζ) Cep. It is close to Zeta that we’ll lastly discover our goal, Delta Cep, which lies about 2.5° to Zeta’s northeast, or that star’s decrease proper early this night. 

Delta Cep varies in brightness between magnitudes 3.6 to 4.3 over a interval of 5.three hundred and sixty six days. So, you should utilize Zeta as a comparability as soon as you discover the star — is Delta shut in brightness to Zeta, or is it notably fainter? Once you’ve famous the relative magnitude, make certain to come back again day by day for the subsequent a number of nights and watch whether or not it brightens or fades. If you’re skilled in taking astrophotos, attempt taking a photograph every evening to chart the star’s adjustments; its cycle could also be simpler to observe on a collection of photographs than together with your reminiscence and your eyes. 

Sunrise: 6:28 A.M.
Sunset: 7:31 P.M.
Moonrise: 3:55 P.M.
Moonset: —
Moon Phase: Waxing gibbous (64%)

Tuesday, September 2
Mercury passes 1.2° north of Regulus at 6 A.M. EDT; the pair is seen within the east simply earlier than dawn, nevertheless it is perhaps a difficult statement. You’ll need to get to a location above the encompassing terrain if potential, with an japanese horizon freed from tall bushes or buildings. 

Rising round 5:30 A.M. native daylight time, Mercury reaches an altitude of 4° roughly half an hour earlier than dawn. It’s now magnitude –1.3, which ought to assist it stand out in opposition to the brightening sky, though binoculars also can assist you find it to the far decrease left of blazing Venus, which stands some 20° excessive right now. Magnitude 1.4 Regulus will probably be more difficult and should solely be seen with binoculars or a telescope, simply over a level to the decrease proper of Mercury within the sky as they’re rising. The star ought to be simply throughout the similar area of view because the planet with a telescope, and positively inside a single binocular area. 

If you’re utilizing a telescope, take a second to give attention to Mercury as properly. The tiny planet seems 5” broad — practically 2.5 occasions smaller than Venus’ disk, at the moment — and is 90 % lit, barely greater than Venus’ 85 %. The latter, brighter planet hangs  2° immediately beneath M44 this morning, so should you’d prefer to catch a binocular view of the 2, you possibly can search for them a little bit earlier, whereas the sky continues to be darkish — attempt some 60 to 90 minutes earlier than dawn. 

Note that you must all the time put away any binoculars or telescope a minimum of a couple of minutes earlier than dawn happens out of your location, which can differ barely from the occasions listed beneath. 

Sunrise: 6:29 A.M.
Sunset: 7:30 P.M.
Moonrise: 4:44 P.M.
Moonset: 12:33 A.M. 
Moon Phase: Waxing gibbous (73%)

Wednesday, September 3
With a waxing Moon lighting the sky for many of the evening, we’re specializing in brighter stars this night. Our goal for tonight is a well-known asterism that’s at the moment seen all evening lengthy. You can catch it already above the horizon within the east an hour after the Sun disappears, then observe its progress because it arcs via the sky in a single day. 

Look east an hour after sundown and also you’ll spot a big diamond of stars — that is the Great Square of Pegasus, which depicts the physique of the Winged Horse. It is bounded by 4 stars; lowest early within the night is magnitude 2.8 Gamma Pegasi. Moving counterclockwise, some 16.5° to its higher proper (west) is magnitude 2.5 Markab (Alpha Peg). The subsequent star is Scheat (Beta Peg), which shines at magnitude 2.5 and sits roughly 13° north (to the higher left) of Markab. As the Great Square is Rising, Scheat seems on the prime of the diamond, immediately above Gamma. 

Finishing off the Great Square is a star that isn’t really in Pegasus — it’s Alpheratz, Andromeda’s magnitude 2.1 alpha star, which lies simply over 14° east (to the decrease left) of Scheat. 

Although the sky is vivid with moonlight tonight, taking the time to be taught the Great Square will assist information your method to many fainter objects when the nights develop darker once more. 

Sunrise: 6:30 A.M.
Sunset: 7:28 P.M.
Moonrise: 5:27 P.M.
Moonset: 1:34 A.M. 
Moon Phase: Waxing gibbous (82%)

Thursday, September 4
We’re again at Saturn early this morning (or late on the third within the western half of the U.S.) to catch a transit of Titan along with its shadow throughout the ringed world. 

The shadow transits first, starting at 1 A.M. EDT (once more, early on the 4th within the japanese half of the U.S. however late on the third within the Mountain and Pacific time zones). At this time, Saturn is excessive within the southeast within the japanese U.S., whereas appreciably decrease and within the east on the West Coast. 

Watch via a telescope as Titan’s shadow slowly seems on the northeastern limb of the planet, taking some 25 minutes to completely emerge. Titan continues to be removed from the limb because it casts its shadow right now, as Saturn continues to be greater than two weeks from opposition. The moon’s shadow takes about two hours to succeed in halfway throughout the disk (round 3 A.M. EDT), as Titan slowly closes in. Titan lastly begins its transit, which can carry it solely partially throughout Saturn’s northern polar area, round 5 A.M. EDT — not lengthy after the shadow has begun its half-hour-long disappearing act over on the northwestern limb. Titan’s shadow is totally gone from the disk by 5:15 A.M. EDT, and Titan’s partial transit ends quarter-hour later. 

Tenth-magnitude Tethys can be transiting this morning, crossing Saturn between about 4:30 A.M. EDT and 6:25 A.M. CDT (be aware the time change, as dawn happens on the East Coast in the course of the transit). Planetary imagers would possibly be capable to decide up the small moon, whereas it might be invisible to visible observers. Its shadow will possible be indistinguishable as properly. 

The Moon passes 0.06° south of Pluto at 10 A.M. EDT.

Sunrise: 6:31 A.M.
Sunset: 7:26 P.M.
Moonrise: 6:03 P.M.
Moonset: 2:40 A.M. 
Moon Phase: Waxing gibbous (89%)

Friday, September 5
Rising earlier than midnight and visual all morning lengthy till daybreak, the distant planet Uranus now resides throughout the area of Taurus the Bull. Its present location makes it simpler than regular to search out, simply 4.5° south-southeast of the Pleiades (M45). By 4 A.M. native daylight time, the area is a few 60° excessive within the east, above the easy-to-find three-star belt of Orion. 

At that point, you’ll discover Uranus to the decrease proper of the Pleiades. With binoculars, scan 4.5° due south of Alcyone (Eta [η] Tauri) to land on a pair of Sixth-magnitude stars in an east-west line. The easternmost star is 14 Tauri, and Uranus is slightly below 3° east of this star. 

The ice big is at the moment 1.8 billion miles (2.9 billion kilometers) from Earth and spans 4” on the sky — small however decidedly nonstellar via a telescope. You could discover it seems “flatter” than the pinprick stars close by, and likewise reveals off a grayish hue.

Uranus is creeping westward via the sky relative to the background stars, ever-so-slowly closing in on 14 Tau (and its japanese companion, 13 Tau), passing south of this pair in December.

Sunrise: 6:32 A.M.
Sunset: 7:25 P.M.
Moonrise: 6:34 P.M.
Moonset: 3:52 A.M. 
Moon Phase: Waxing gibbous (95%)