Sky This Month: October 2023

An annular eclipse of the Solar on Oct. 14 is the massive occasion this month, with a lot of the U.S. seeing a partial eclipse. Saturn is beautiful within the evenings, whereas Jupiter is nearing its greatest for the yr, seen all night time. And it’s a very good time to trace down Uranus and Neptune in binoculars. Venus dazzles within the morning sky, rising about 4 hours earlier than the Solar. The second week of October can also be a good time to view the zodiacal gentle.

Saturn is effectively positioned all night for statement with a telescope. It begins out at magnitude 0.5 and dips by 0.1 magnitude throughout October. The planet’s location in southwestern Aquarius provides luster to this dimly lit area of sky. 

The ringed planet stands excessive within the south effectively earlier than midnight. It units by 4 a.m. on Oct. 1 and two hours earlier on Halloween. You’ll discover Saturn 5° northeast of a waxing gibbous Moon in a single day on Oct. 23/24.

Small telescopes readily showcase the rings. Bigger scopes reveal little extra of the planet visually; particulars on the 18″-wide disk are greatest captured by utilizing high-speed video and stacking the most effective frames. 

Saturn’s ring system stays greater than 41″ vast from its distance of over 9 astronomical models (837 million miles; 1 astronomical unit, or AU, is the common Earth-Solar distance). The present ring tilt is about 10°. The outer A hoop is separated from the brighter B ring by the darkish Cassini Division. The diaphanous inside C ring is lighter and partly clear. 

Saturn’s brightest moon is magnitude 8.5 Titan. It’s north of the planet Oct. 9/10 and 25/26, and south Oct. 1/2 and 17/18. Some evenings, a star lies near the planet, corresponding to a Tenth-magnitude discipline star Sept. 30/Oct. 1. It may be simply mistaken for a moon.

You can find three Tenth-magnitude moons — Tethys, Dione, and Rhea — orbiting nearer in than Titan. Their orbits lie within the aircraft of the rings and because the angle shrinks, transits of the planet’s disk happen. Tethys does this twice, as soon as on Oct. 15/16 and once more on the seventeenth. Tethys begins transiting shortly after 1:00 a.m. EDT on the sixteenth (nonetheless the fifteenth in western time zones), taking simply over 70 minutes to cross the disk. Its tiny shadow follows inside 5 minutes of the transit begin, although you’ll want distinctive seeing situations to view it. The sequence repeats Oct. 17 starting round 10:20 p.m. EDT, with Tethys taking about the identical period of time to cross the disk. Observe that these are approximate occasions; start observing 15 to twenty minutes early. Recording video is best than visually making an attempt to trace the occasion.

Enceladus shines at twelfth magnitude near the sting of the disk. Because the rings shut over the subsequent few years, this moon will turn into simpler to identify because the glare from the rings diminishes.

Iapetus is lower than 1′ east of Saturn the morning of Oct. 1. It lies between Titan and Dione. The Tenth-magnitude discipline star is a mere 15″ from Iapetus, making this a very good night time to identify the moon, glowing close to Eleventh magnitude. Iapetus is racing towards japanese elongation on the 18th, dimming to twelfth magnitude.

Neptune is seen all night time in Pisces. It’s past the naked-eye restrict, requiring binoculars or a telescope to spy. At magnitude 7.7, the distant world’s brilliance is much like many different objects’, so it’s greatest to make use of brighter stars as a information.

Magnitude 5.5 20 Piscium serves this objective effectively. It’s westernmost in a line of three stars of comparable brightness south of the Circlet of Pisces. Neptune stands 33′ west of 20 Psc on Oct. 1 and strikes west every night time. In mid-October, Neptune could be very near a magnitude 7.3 star, arriving simply 6′ due north of it on the fifteenth.

By a telescope, Neptune spans 2″ and glows bluish. It’s solely a few weeks previous opposition at the beginning of October, making this a good time to view the planet. 

Jupiter is one month from opposition as October opens and rises simply after 8 p.m. native daylight time. It’s gaining in diameter and brightness; by month’s finish it’s reached a span of 49″ and a magnitude of –2.9, its most good of the yr.

Jupiter is positioned in southern Aries. On the first, the planet lies 3° south of a waning gibbous Moon.

Jupiter’s disk is filled with element when seen by a telescope, although newcomers making an attempt their first view will discover a lot of it refined. Affected person viewing aids in recognizing wonderful particulars. The dual equatorial belts are the darkest options, together with the sometimes seen Nice Pink Spot. 

The Galilean moons orbit each two to 17 days. Within the runup to opposition, transits of the moons are preceded by their shadows with reducing time separation. By early subsequent month, each shadow and moon transit virtually concurrently. After opposition, the moon leads, adopted by its shadow.

Try the transit of Io Oct. 5, starting with the moon’s shadow at 9:50 p.m. EDT, simply as Ganymede is skimming the planet’s south pole. Io slips onto the disk shortly after 10:30 p.m. EDT. The shadow leaves the disk at midnight EDT, whereas Io follows 41 minutes later. On the twenty eighth, Io’s shadow leads the moon by solely 9 minutes, beginning at 10:02 p.m. EDT. Different transits with intermediate timing happen Oct. 12/13 and 21.

Ganymede performs a wonderful transit Oct. 12, previous to Io’s occasion the identical night. Beginning at 9:56 p.m. EDT (not seen from Mountain and Pacific time zones), its large black shadow crosses the planet’s southern polar area. Io’s shadow seems at 11:44 p.m. EDT, simply as Ganymede’s shadow is leaving the southwestern limb. Io’s transit begins at 12:18 a.m. EDT on the thirteenth (Oct. 12 in all different U.S. time zones), adopted 20 minutes later by Ganymede. 

Europa transits the evenings of Oct. 2/3, 9/10, and 16/17, and early on the twenty fourth. Every occasion begins progressively later within the night time or early morning. Because of the moons’ inclined orbital aircraft relative to our line of sight, Callisto passes north or south of the disk this month.

Uranus stands about 9° southwest of the Pleiades (M45) and 9° northeast of Jupiter. Scan the sky between Jupiter and M45 to discover a small grouping of Fifth-magnitude stars together with Tau (τ) Arietis. Uranus is simply over 3° south of this star. The planet glows at magnitude 5.7. Its bluish hue ought to stand out in opposition to the remainder of the starfield. 

Uranus strikes westward because it approaches subsequent month’s opposition, passing between a pair of extensively spaced Seventh-magnitude stars from the sixteenth to the 18th. By month’s finish, Uranus lies 18.7 AU from Earth and is simply 4″ vast by a telescope.

Early within the night on the twenty ninth, you’ll discover Uranus about 2° south of the brilliant Moon. Our satellite strikes eastward and later that night time passes by a bunch of Fifth- and Sixth-magnitude stars, occulting two of them (63 and 65 Arietis) from some components of the nation.

Venus is an excellent morning star, beginning the month 7° west of Regulus, Leo’s brightest star. At magnitude –4.7, Venus is seen within the japanese sky quickly after rising round 3:30 a.m. native daylight time. By the Tenth, Venus is magnitude –4.6 and stands 2.5° south of Regulus. The pair is joined by a waning crescent Moon about 5° away.

Venus traverses southern Leo and on the thirty first stands 6° northwest of Beta (β) Virginis. By a telescope, Venus’ disk is a 32″-wide, 37-percent-lit crescent on the first. The disk shrinks to 22″ by the thirty first and is 54 % lit. Venus reaches western elongation (46°) on the twenty third. The planet is now 50 % lit, referred to as dichotomy. Nevertheless, observers might even see the precise second of dichotomy occurring earlier than or after this date. That is referred to as Schröter’s impact, named for the German astronomer who first famous it, in 1793. At western elongations, dichotomy could be as much as 6 days late. The phase is greatest decided in brilliant twilight.

Venus additionally acts as a pleasant information for the road of the ecliptic if you wish to observe the zodiacal gentle. For a number of days round New Moon, verify for this faint cone-shaped glow rising from the japanese horizon earlier than morning twilight begins.

Mercury makes a short morning look at magnitude –1.1 early within the month. Its elongation from the Solar is reducing rapidly. On the first, the planet stands 4° excessive within the east 50 minutes earlier than dawn. By the 4th, it has dropped to 2° excessive on the identical time. Mercury reaches conjunction with the Solar Oct. 20 and returns to the night sky later subsequent month.

Mars is just too near the Solar for statement this month.

An annular eclipse of the Solar takes place Saturday, Oct. 14. Simply six months earlier than the much-anticipated 2024 total solar eclipse, it affords an incredible alternative to apply observing that occasion. A lot of the U.S. will see a partial eclipse with diminishing proportion farther from the central observe. Solely observers alongside that heart line will see the annular eclipse.

The observe of annularity, the place the Moon crosses precisely in entrance of the Solar however leaves an excellent ring at central eclipse — and subsequently all the time requires eclipse glasses to watch — runs from Oregon to Texas. Annularity begins close to Eugene, Oregon, simply earlier than 9:17 a.m. PDT and ends in Texas close to Corpus Christi round 12:01 p.m. CDT.

The eclipse continues by Mexico, Belize, Honduras, Nicaragua, and Panama. It then enters Colombia and begins to show eastward throughout Brazil. The trail enters the Atlantic Ocean south of Natal, the place the Solar units throughout the ultimate partial phase.

Two weeks after the annular eclipse, a partial eclipse of the Moon happens Oct. 28, seen in Europe, Africa, India, and Asia. Observers within the northeastern U.S. would possibly see the Full Moon rise with a dusky southern edge, the results of the ultimate phases of the penumbral eclipse. 

Rising Moon: One superb sight after one other

The waxing crescent Moon rides low within the autumnal night sky but sports activities an impressive array of wonders alongside the light-dark terminator that make it worthwhile to observe every night time.

On the twenty first, the rugged lunar Apennines thrust diagonally into the sunlit area close to the lunar equator. Mendacity to their north alongside the terminator are two younger craters — Autolycus and Aristillus — sticking up proudly above the decrease plains. They shaped a few billion years in the past close to the tip of the final main lunar bombardment. The low Solar angle highlights the rugged apron of particles that splattered round every round formation, whereas their steep, excessive partitions forestall this gentle from reaching a lot of the flooring. Keep for an hour on close by fabulous Archimedes and watch the lengthy shadows stretching into the terminator retreat because the rotation of the Moon causes the Solar to rise.

Take into account the traits of those “youthful” craters. The bigger impactor that created Aristillus was capable of excavate much more materials — there are lots of extra streaks and ridges pointing radially away from this crater than Autolycus. Additionally examine the edges and aprons to these of the big, spherical craters Hipparchus and Albategnius south of the equator. Proof of the latter’s larger age comes from their degraded options, the results of incessant pounding from smaller impacts over time. Their central peaks are decrease, their partitions are rounded and pockmarked with dozens of craterlets, and their aprons have been smoothed out. 

Return on the twenty second to see how the upper Solar angle begins to hide the aprons’ roughness. You may additionally discover the looks of the Straight Wall positioned within the southern third of the Moon.

Meteor Watch: What Halley leaves behind

The height of the Orionid meteor bathe coincides properly with a First Quarter Moon this yr.  After the September lull, observers look ahead to the Orionids partially as a result of they’re produced from particles shed throughout historic passes of the well-known Halley’s Comet. The Orionids may attain a zenithal hourly charge of 20 to 30 meteors per hour in a single day on Oct. 21/22, the night time of most, akin to an observable charge of 15 to twenty per hour between 2 a.m. and daybreak because the radiant in northeastern Orion rises greater within the sky.

The bathe is energetic from Oct. 2 by Nov. 7, and charges away from the utmost are a lot decrease. The radiant rises by 11 p.m. native daylight time. As with all meteor showers, the most effective observing time is within the early morning, when you’re on the main facet of Earth and heading straight into the meteor stream.

Comet Search: The clown with inexperienced hair

Peaking at eighth magnitude, Comet 103P/Hartley (additionally referred to as Hartley 2) can be an honest telescopic sight after midnight from nation skies with a 4-inch scope. Binoculars might pull it in, too. From the suburbs, it’s in vary of a 10-inch scope.

Though Hartley 2 handed closest to Earth final month, it’s nonetheless closing in on the Solar for perihelion on the twelfth. The mile-long, bowling-pin-shaped soiled snowball orbits Sol each 6.48 years. We get a very good probability at it each 12.96 years, however that slight shortfall in time implies that for every return, Earth arrives later so the comet is farther and fainter. Subsequent month is our final view brighter than Tenth magnitude for a number of many years.

We do get a comfort prize: On the twelfth and thirteenth, the “furry star” is simply 0.5° from NGC 2392 in Gemini, generally referred to as the Lion or the Clown-faced nebula. To imagers, each can be inexperienced. The upper floor brightness of the planetary nebula will set off our inexperienced cone receptors by 10-inch scopes, however visually the comet’s fuzz will stay ashen grey. We’re seeing the comet virtually head-on. Are you able to discover which facet is out of spherical?

Finding Asteroids: A drop within the water

Can you progress your scope straight up and down? That’s all it takes to find the big asteroid 8 Flora this month. Simply earlier than 10 p.m. native daylight time, Saturn and Iota (ι) Aquarii cross the meridian, the imaginary line rising overhead from the southern horizon. Shift the view 7° straight right down to land on Flora. For those who don’t know your precise discipline of view, there are on-line calculators for any scope-eyepiece mixture. 

Use the chart to maintain tabs on the patterns of triangles, voids, and clumps as you close to the spot. On the Seventh and eighth, Flora varieties a decent pair with a magnitude 7.4 discipline star. The 85-mile-wide, practically spherical mountain can be notably fainter at magnitude 9.2. You probably gained’t see any motion throughout your observing session as a result of Flora is simply exiting a hairpin retrograde arc, its movement briefly parallel to Earth’s. Take a break from Oct. 22 to 25, when the passing waxing gibbous Moon throws out its veil of sunshine. 

Flora was found by Englishman John Hind in 1847, many years after Giuseppe Piazzi had pegged 1 Ceres in 1801.