The Sky This Week from Oct. 24 to 31: Iapetus stands close to Saturn

Sky This Week is dropped at you partially by Celestron.

Friday, October 24
The Moon passes 0.5° south of Antares at 9 P.M. EDT. However, the pair units an hour and a half earlier; strive catching them about 40 minutes after sundown, when they’re low within the southwest. 

Already excessive within the sky after sundown and persevering with to rise is Andromeda the Princess, positioned within the east. Her curving determine seems to the left of the Great Square of Pegasus, considered one of whose stars — 2nd-magnitude Alpheratz — is definitely positioned in Andromeda and cataloged as its alpha star. 

M31 is probably the most well-known galaxy claimed by the Princess, however actually not the one one. NGC 891 is a Tenth-magnitude edge-on spiral that can also be known as the Silver Sliver Galaxy or the Outer Limits Galaxy. Located simply 3.5° from magnitude 2.1 Gamma (γ) Andromedae, you may spot it beneath darkish skies with only a small scope, although bigger telescopes (6 inches or extra) are higher for choosing out element, such because the thick, darkish mud belt that runs via its aircraft. One of the most effective methods to seize this galaxy visually is to make use of averted imaginative and prescient, centering it within the eyepiece after which glancing to the nook of the sphere of view, permitting the dim galaxy to come out in your peripheral imaginative and prescient.

Sunrise: 7:21 A.M.
Sunset: 6:07 P.M.
Moonrise: 10:35 A.M. 
Moonset: 7:34 P.M.
Moon Phase: Waxing crescent (12%)
*Times for dawn, sundown, moonrise, and moonset are given in native time from 40° N 90° W. The Moon’s illumination is given at 10 P.M. native time from the identical location.

Saturday, October 25

U.S. West Coast observers are in luck this morning, as Io and Europa forged their shadows collectively on Jupiter’s cloud tops as twilight is brightening the sky — an occasion that happens after dawn for the remainder of the U.S. 

40 minutes earlier than dawn, Jupiter is sort of 80° excessive within the south. Through a telescope, you’ll spot a pair of shadows on the disk — one practically midway throughout its journey from east to west, and the opposite close to the japanese limb. The shadow roughly within the middle of the planet is Io’s, forged by its mum or dad moon simply off the japanese limb. The darkish spot that has simply begun crossing and is nearer to the limb belongs to Europa, to Io’s east. (Much farther east of this pair is Ganymede, whereas Callisto lies alone to the planet’s west.)

See how lengthy you may comply with the moons and their shadows because the sky brightens. Io begins to transit at 6:44 A.M. PDT, not lengthy earlier than dawn (be aware the precise time of dawn will rely in your location). 

Sunrise: 7:22 A.M.
Sunset: 6:06 P.M.
Moonrise: 11:35 A.M. 
Moonset: 8:18 P.M.
Moon Phase: Waxing crescent (18%)

Sunday, October 26
Saturn’s moon Iapetus reaches inferior conjunction tonight, sitting 1.3′ due north of Saturn and glowing at roughly eleventh magnitude. This oft-elusive moon is simpler to search out when it’s near its mum or dad planet, so give it a strive tonight. 

Magnitude 0.7 Saturn is highest round 10 P.M. native daylight time, when it’s the brightest level of sunshine within the southern sky, hanging beneath the Circlet of Pisces and to the far higher left of Fomalhaut in Piscis Austrinus. Through a telescope, its rings stretch 43” extensive, whereas its disk is nineteen” throughout. 

At 10 P.M. CDT, Saturn’s largest and brightest moon, Titan, lies far to the planet’s west. Much nearer to the western fringe of the rings is smaller, Tenth-magnitude Dione. Just above the rings’ japanese tip is equally shiny Tethys, with Rhea farther to the east. And north of the planet is Iapetus. Note that whereas the positions of Dione, Tethys, and Rhea will change all through the night time, Titan and Iapetus ought to stay comparatively stationary for all observers. 

Sunrise: 7:23 A.M.
Sunset: 6:04 P.M.
Moonrise: 12:29 P.M.
Moonset: 9:10 P.M.
Moon Phase: Waxing crescent (26%)

Monday, October 27
Jupiter passes 7° south of Pollux in Gemini at 11 A.M. EDT. You can catch the pair late this night, seen by midnight native daylight time within the east and rising increased into the early-morning hours. Jupiter can’t be missed, glowing at magnitude –2.2 to the decrease proper of Castor and Pollux, the Twins’ heads. 

Pollux is the decrease and extra golden of the pair — it’s additionally barely brighter, shining at magnitude 1.2. Castor above it seems extra blue-white and is magnitude 1.6. Castor is a well-known double star, seen as two factors of sunshine via a telescope. One element is 2nd magnitude, whereas the opposite is a fainter third magnitude. 

Aim your telescope at Jupiter and East Coast observers can catch a disappearing act as Io, off to the planet’s west, disappears simply after 12:10 A.M. EDT on the twenty eighth, winking out because it passes into Jupiter’s lengthy, darkish shadow. Io will reappear from occultation about 3:45 A.M. EDT (now the twenty eighth throughout the U.S.), when it pops into view off the northeastern limb.

Sunrise: 7:24 A.M.
Sunset: 6:03 P.M.
Moonrise: 1:16 P.M.
Moonset: 10:09 P.M.
Moon Phase: Waxing crescent (35%)

Tuesday, October 28
Tonight is a superb alternative to observe dwarf planet 1 Ceres transfer relative to the background stars of Cetus the Whale. A bonus: You can achieve this even when all you’ve gotten is binoculars! 

Ceres is now eighth magnitude, inside vary of binoculars and small scopes. By 9 P.M. native daylight time, it’s 30° excessive within the southeast, positioned 7° above 2nd-magnitude Diphda (additionally known as Deneb Kaitos and cataloged as Beta [β] Ceti) and about 2° west of magnitude 4.8 Phi¹ (φ¹) Ceti. 

Ceres is passing notably near a equally shiny area star — it’s the southernmost gentle of the 2. Over the course of an hour or two, you may discover their relative positions change as Ceres slides from east to west south of the star. 

Sunrise: 7:25 A.M.
Sunset: 6:02 P.M.
Moonrise: 1:56 P.M.
Moonset: 11:14 P.M.
Moon Phase: Waxing crescent (45%)

Wednesday, October 29
The Moon passes 0.1° north of Pluto at 3 A.M. EDT. The dim, distant dwarf planet is already a problem for all however skilled observers with giant scopes, and the Moon renders it just about invisible. If you wish to search out Pluto, it’s finest to attend for a moonless night time to take action. 

First Quarter Moon happens at 12:21 P.M. EDT. It’s seen within the south in Capricornus at sundown and stays up virtually all night, setting within the half hour earlier than midnight. The most noticeable function on our satellite tv for pc is one that’s dynamic — the terminator, the dividing line between night time and day, which stands midway throughout the seen face of the Moon at First Quarter. Visible on the lit half of the Moon are giant, darkish areas — these are maria, or seas, though they had been fashioned by lava, not water. Along the terminator to the south, you’ll spot many giant, spherical craters. Take a while to discover the rugged terrain with a telescope. Also discover the big white function near the southeastern limb — that is the crater Stevinus, which is surrounded by shiny rays of ejecta (materials thrown up and out throughout the affect that created the crater). This crater has a big central peak — a typical function in affect craters — that may be seen fairly effectively with a telescope. 

Mercury reaches biggest japanese elongation (24°) at 6 P.M. EDT. The photo voltaic system’s innermost planet is low on the horizon after sundown, however shiny sufficient that these with a transparent view to the southwest might be able to catch it. Try wanting half an hour after sundown, when magnitude –0.1 Mercury is 3° excessive. To its proper is far fainter Mars (magnitude 1.4); you would possibly want binoculars to select it out in opposition to the brighter background. Come again tomorrow for the same view, once we deal with this pair of planets within the night sky. 

Sunrise: 7:26 A.M.
Sunset: 6:01 P.M.
Moonrise: 2:29 P.M.
Moonset: —
Moon Phase: Waxing gibbous (55%)

Thursday, October 30
Return to the night sky to catch Mercury now lower than 9° west of Antares, the brilliant purple coronary heart of Scorpius the Scorpion. Half an hour after sundown, Mercury is 3.5° excessive, with Antares to its higher left and Mars to its proper. 

Mercury is the brightest gentle right here, glowing at magnitude –0.1. Antares is subsequent, shining at magnitude 1.1, whereas Mars is a tad fainter at magnitude 1.4. Mercury shall be best to see and should come out of the twilight with out optical support. If you’ve gotten bother recognizing Mars, use binoculars or a small scope to slowly scan some 5.4° to the best (northwest) of Mercury to search for its faint, ruddy glow. 

Through a telescope, Mars’ disk is tiny, simply 4”, and doesn’t present floor options at this dimension. Mercury seems bigger — 7” extensive — and whereas no floor options are seen right here both, you may see that it’s not absolutely illuminated, however a 60-percent-lit gibbous. 

The pair of planets units by about 7 P.M. native daylight time, with Antares following shortly after. 

Sunrise: 7:28 A.M.
Sunset: 6:00 P.M.
Moonrise: 2:58 P.M.
Moonset: 12:21 A.M.
Moon Phase: Waxing gibbous (65%)

Friday, October 31
Start your Halloween off with a spooky sight within the early-morning sky: NGC 7789, an open cluster also called the Screaming Skull. You’ll discover this star group about 20° excessive within the north an hour earlier than dawn, slightly below the W-shaped star sample of Cassiopeia. 

Start at Caph (Beta Cassiopeiae) and drop down a tad lower than 3° towards the horizon (southwest on the sky). NGC 7789 glows at magnitude 6.6 and spans about 25’, making it a fantastic binocular or small scope goal. Discovered by Caroline Herschel, this wealthy younger cluster of stars is usually known as Caroline’s Rose. But Astronomy contributor Stephen James O’Meara calls NGC 7789 the Screaming Skull as a result of he — and plenty of others — see a cranium hidden within the patterns of stars and darkish areas as a substitute. What do you see? 

You can even catch this cluster within the night sky. An hour after sundown, you’ll discover it within the northeast as a substitute.

So, why are we up early? It’s additionally to see the blazing planet Venus rising simply forward of Spica, Virgo’s alpha star. Magnitude –3.9 Venus is the brightest gentle within the japanese sky because it rises round 6 A.M. native daylight time. Half an hour later, roughly an hour earlier than dawn, 1st-magnitude Spica has simply cleared the horizon. Wait one other half-hour — half an hour earlier than dawn — and the pair is about 8° excessive, seen in case your horizon is pretty clear. Spica sits simply to Venus’ decrease proper, and can grow to be ever-harder to see because the sky brightens. 

Venus will move 4° due north of Spica tonight at midnight EDT. The planet will sit somewhat nearer to the star if you happen to’re up tomorrow morning on the identical time to catch them.

Sunrise: 7:29 A.M.
Sunset: 5:58 P.M.
Moonrise: 3:24 P.M.
Moonset: 1:31 A.M.
Moon Phase: Waxing gibbous (75%)