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The night sky tonight and on any clear night offers an ever-changing display of fascinating objects you can see, from stars and constellations to bright planets, often the moon, and sometimes special events like meteor showers.
Observing the night sky can be done with no special equipment, although a sky map can be very useful, and a good telescope or binoculars will enhance some experiences and bring some otherwise invisible objects into view. You can also use astronomy accessories to make your observing easier, and use our Satellite Tracker page powered by N2YO.com (opens in new tab) to find out when to see the International Space Station and other satellites. You can also capture the night sky by using any of the best cameras for astrophotography, along with a selection of the best lenses for astrophotography.
Read on to find out what’s up in the night sky tonight (planets visible now, moon phases, observing highlights this month) plus other resources (skywatching terms, night sky observing tips and further reading).
Related: The brightest planets in October’s night sky: How to see them (and when)
Monthly skywatching information is provided to Space.com by Chris Vaughan of Starry Night Education, the leader in space science curriculum solutions. Follow Starry Night on Twitter @StarryNightEdu and Chris at @Astrogeoguy.
Editor’s note: If you have an amazing skywatching photo you’d like to share for a possible story or image gallery, please contact managing editor Tariq Malik at [email protected].
Calendar of observing highlights
Saturday, October 1 – Delphinus Swims the Southern Sky (all night)
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During the evening in early October, the small constellation of Delphinus is positioned high in the southern sky. Look for its five 4th-magnitude stars shining just to the lower left (or celestial southeast) of the line connecting the bright stars Deneb and Altair.
According to Greek legend, Poseidon, god of the seas, was assisted in a matter of the heart by a friendly dolphin, so he rewarded it with a place of honor in the heavens. Delphinus’ brightest two stars are bluish Sualocin, at the top of its head, and whitish Rotanev, at the nape of its neck. Those funny appellations are actually the name of 19th-century astronomer Nicolaus Venator spelled backward. Gamma Delphinus, the star marking the dolphin’s nose, is a close-together double star with one component a greenish color. Despite swimming close to the Milky Way, Delphinus’ only prominent deep-sky objects are two globular clusters designated NGC 7006 and NGC 6934, which are also numbers C42 and C47, respectively, on Sir Patrick Moore’s Caldwell List.
Sunday, October 2- First Quarter Moon (at 8:14 p.m. EDT)
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The moon will complete the first quarter of its journey around Earth on Sunday, Oct. 2 at 8:14 p.m. EDT or 5:14 p.m. PDT. That translates to Monday, Oct. 3 at 00:14 GMT. At first quarter, the moon’s 90-degree angle from the sun will cause us to see it half-illuminated — on its eastern side, and shining among the Teapot-shaped stars of Sagittarius after dusk. At first quarter, the moon always rises around midday and sets around midnight, so it is visible in the afternoon daytime sky, too. The evenings surrounding first quarter are the best ones for seeing the lunar terrain when it is dramatically lit by low-angle sunlight, especially along the terminator, the pole-to-pole boundary that separates the lit and dark hemispheres.
Wednesday, October 5 – Bright Moon near Saturn (evening)
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After dusk on Wednesday evening, Oct. 5, look in the lower part of the southeastern sky for the waxing gibbous moon shining a slim palm’s width to the lower left (or five degrees to the celestial southeast) of Saturn‘s yellowish dot. That spacing will be just close enough for them to share the view in most binoculars (green circle). By the time Saturn sets in the west-southwest around 2:30 a.m. local time, the diurnal rotation of the sky will lift the moon to Saturn’s upper left.
Thursday, October 6 – Vesta ends its Retrograde Loop (overnight)
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On Thursday night, Oct. 6, the westward retrograde motion (red path with date:hr) of the large main belt asteroid designated (4) Vesta will stow to a stop. After Thursday, it will resume eastward motion through the stars of eastern Capricornus. The magnitude 6.6 asteroid is bright enough to see in good binoculars and any size of telescope. Look for it shining a slim fist’s diameter to the lower left (or 8.75 degrees to the celestial southeast) of Saturn and a palm’s width (six degrees) from the stars Deneb Algedi and Zeta Capricorni.
Friday, October 7 – Crater Copernicus (all night)
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The nights surrounding Friday, October 7 will be particularly good for viewing the prominent crater Copernicus, which is located in eastern Oceanus Procellarum, the dark region located due south of Mare Imbrium and slightly northwest of the moon’s center. This 800 million-year-old impact scar is visible with unaided eyes and binoculars — but telescope views will reveal many more interesting aspects of lunar geology. Several nights before the moon reaches its full phase, Copernicus exhibits heavily terraced edges (due to slumping), an extensive ejecta blanket outside the crater rim, a complex central peak, and both smooth and rough terrain on the crater’s floor. Around the full moon, Copernicus’ ray system, extending 500 miles (800 km) in all directions, becomes prominent. Use high magnification to look around Copernicus for small craters with bright floors and black haloes — impacts through Copernicus’ white ejecta that excavated dark Oceanus Procellarum basalt and even deeper highlands anorthosite.
Saturday, October 8 – Moon Pursues Jupiter (all night)
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After it rises in the eastern sky around dusk on Saturday evening, October 8, the bright, waxing gibbous moon will shine several finger widths below (or 3.5 degrees to the celestial southeast) of the very bright planet Jupiter — allowing the duo to share the view in binoculars (green circle) all night long as they slide west. By the time they set around 6 a.m. local time the diurnal rotation of the sky will swing the moon above Jupiter. Due to the moon’s continuous easterly orbital motion, skywatchers viewing the duo later, or in more westerly time zones, will see the moon positioned a little farther from the planet.
Saturday, October 8 – Mercury at Greatest Western Elongation (pre-dawn)
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On Saturday, October 8, the planet Mercury will reach a maximum angle of 18 degrees from the sun, and peak visibility, for the current morning apparition. Look for the innermost planet shining brightly while it climbs the eastern pre-dawn sky between about 5:45 and 6:30 a.m. in your local time zone. In a telescope (inset) Mercury will exhibit a 50%-illuminated, waxing phase. Mercury’s position above the nearly upright morning ecliptic (green line) will make this an excellent apparition for Northern Hemisphere observers, but a very poor one for those located south of the equator, where the ecliptic will be tilted.
Sunday, October 9 – Full Hunter’s Moon (at 20:55 GMT)
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The full moon of October, which will occur at 4:55 p.m. EDT, 1:55 p.m. PDT, or 20:55 GMT, on Sunday, October 9, is traditionally called the Hunter’s Moon, Blood Moon, or Sanguine Moon. The Anishinaabe people of the Great Lakes region call this moon Binaakwe-giizis, the Falling Leaves Moon, or Mshkawji-giizis, the Freezing Moon. The Cree Nation of central Canada calls it Opimuhumowipesim, the Migrating Moon – the month when birds are migrating. The Haudenosaunee (Iroquois / Mohawk) of Eastern North America uses Kentenha, the Time of Poverty Moon. Full moons in October always shine in or near the stars of Cetus and Pisces. Since it’s opposite the sun on this day of the lunar month, the full moon will rise at sunset and set at sunrise.
Tuesday, October 11 – Bright Moon Approaches Uranus (late night)
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On Tuesday evening, October 11 in the Americas, the very bright, waning gibbous moon will shine a short distance to the upper right (or celestial west) of the blue-green, magnitude 5.7 speck of Uranus. When the pair clears the eastern rooftops in the Atlantic and Eastern Time Zones, the moon will be positioned several degrees from the planet. Since the moon’s orbital motion (green line) will be carrying it steadily eastward, observers looking later, and in the more westerly time zones, will see the moon progressively closer to Uranus. Around 06:00 GMT, telescope-owners in the northwestern USA, Alaska, northern and western Canada, and Greenland can see the moon occult Uranus – the tenth in a series of consecutive lunar occultations of that planet. The rest of North America will only see the moon pass closely above (north) Uranus. Use Starry Night to look up your timing for the event.
Friday, October 14 – Waning Moon near Mars (overnight)
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When the waning gibbous moon clears the treetops in the east-northeastern sky around 10 p.m. local time on Friday, October 14, it will be accompanied by the bright, reddish dot of Mars shining several finger-widths to its lower right (or three degrees to the celestial south). The pair will be close enough to share the view in binoculars (green circle) all night long – but, by sunrise, the moon will be farther from and directly above the planet.
Saturday, October 15 – Mars Passes the Crab Nebula (all night)
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For about ten nights surrounding Saturday, October 15, the easterly motion of Mars will carry it closely past the Crab Nebula, otherwise known as Messier 1, in Taurus. Mars will move to within a thumb’s width above (or 1.5 degrees to the celestial northwest of) M1 on October 11 — close enough to share the view in a backyard telescope (green circle). At their closest approach on Saturday, Mars will be positioned about a finger’s width to the upper left of the magnitude 8.4 supernova remnant. On the following nights, Mars will shift more to the nebula’s upper left (or northeast). The relatively faint Crab Nebula is best viewed in larger telescopes under dark skies. Since the waning moon will pass close to the pair on October 14, plan to view the nebula before the crescent moon rises on October 17-20.
Sunday, October 16 – Moon Meets Castor and Pollux (overnight)
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When the waning crescent moon rises in the eastern sky at around 11 p.m. local time on Sunday, October 16, it will be forming a pretty triangle to the right (or celestial southwest) of the up-down pair of bright stars of Gemini, Castor and Pollux. During the night, the moon’s easterly orbital motion will carry it closer to Pollux (the lower, more easterly star), allowing all three objects to share the view in binoculars (green circle) until dawn.
Monday, October 17 – Third Quarter Moon (at 17:15 GMT)
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The moon will complete three-quarters of its orbit around Earth, measured from the previous new moon, on Monday, October 17 at 1:15 p.m. EDT and 10:15 a.m. PDT or 17:15 GMT. At the third (or last) quarter phase the moon appears half-illuminated, on its western, sunward side. It will rise around midnight local time, and then remain visible until it sets in the western daytime sky in the early afternoon. Third-quarter moons are positioned ahead of the Earth in our trip around the sun. About 3½ hours later, Earth will occupy that same location in space. The week of dark, moonless evening skies that follow this phase is the best one for observing fainter deep sky targets.
Tuesday, October 18 – Half-Moon Approaches the Beehive (pre-dawn)
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During the wee hours of Tuesday morning, October 18, the waning crescent moon will be climbing the eastern sky above the faint stars of Cancer. The moon’s easterly orbital motion (green line) will steadily carry it closer to central Cancer. Towards dawn, the moon will shine binoculars close to Cancer’s large open star cluster, which is known as Messier 44 or the Beehive. To see the cluster’s swarm of stars, which span more than twice the moon’s diameter, hide the moon just above your binoculars’ field of view (green circle).
Tuesday, October 18 – Juno Reverses Course (all night)
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On Tuesday, October 18, the westward motion of the main belt asteroid designated (3) Juno will slow to a stop as it completes a retrograde loop that it began in late July. After tonight it will resume eastward prograde motion through the stars of central Aquarius. The magnitude 8.6 minor planet can be spotted in binoculars (green circle) and any telescope. This evening it will sit partway up the southern sky between Jupiter and Saturn, within a triangle formed by the medium-bright stars Lambda, Tau, and Sigma Aquarii.
Wednesday, October 19 – Two Shadows and the Great Red Spot Cross Jupiter (17:20 to 19:00 GMT)
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From time to time, observers with good telescopes can watch the small, round, black shadow of one of the Galilean moons slip across Jupiter’s disk. On Wednesday evening, October 19, sky-watchers across Africa, Europe, and Asia can see a rare treat when two shadows cross the southern hemisphere of Jupiter, together with the Great Red Spot! At 7:19 p.m. Central European Summer Time or 17:20 GMT, the Great Red Spot and the small shadow of Europa will join the large shadow of Ganymede, which began its own crossing of the planet an hour earlier. Ganymede’s shadow will leave Jupiter around 9 p.m. CEST or 19:00 GMT, leaving Europa’s shadow to continue on until 9:45 p.m. CEST or 19:45 GMT. The GRS will disappear about 45 minutes later.
Thursday, October 20 – Crescent Moon Occults Bright Star Eta Leonis (pre-dawn)
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In the eastern sky on Thursday morning, October 20, observers across most of the continental USA and southern Canada can use binoculars (green circle) and backyard telescopes to see the crescent moon occult the bright star Eta Leonis, the star marks the chest of Leo, the Lion. Exact timings will vary by location, so use an app like Starry Night to determine the precise times where you are. In Denver, the bright, leading edge of the moon will cover Eta Leonis at 4:58 a.m. MDT or 10:58 GMT. The star will emerge from behind the moon’s opposite, dark limb at 6:14 a.m. MDT. In more easterly time zones, the event will occur in a brightening sky before sunrise. For best results, start watching a few minutes ahead of each time noted.
Friday, October 21 – Orionids Meteor Shower Peak (pre-dawn)
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The annual Orionids meteor shower is produced when the Earth crosses through a cloud of small particles dropped by repeated passages of Comet Halley in its orbit. Viewed in a dark sky during the peak of the shower, 10-20 bright and fast-moving meteors are usually seen each hour. Although this shower technically runs from September 26 to November 22, it will peak in the Americas on the afternoon of Friday, October 21, when Earth will be crossing the densest region of the particle field. Since meteors are only visible in a dark sky, the best viewing time for the USA and Canada will be the wee hours of Friday morning before the waning crescent moon rises, and late on Friday night. Those shoulder-peak times will yield somewhat fewer meteors. Orionids meteors will appear anywhere in the sky, but they can be traced back to their radiant in the constellation of Orion.
Friday, October 21 – Old Crescent Moon near Ceres (pre-dawn)
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During the hours before dawn on Friday morning, October 21, look in the eastern sky for the old crescent moon shining prettily. The dwarf planet Ceres will be positioned several finger-widths to the upper left (or 3 degrees to the celestial north) of the moon — close enough to share the view in binoculars (green circle). With a magnitude of only 8.84, Ceres will be seen more easily in a backyard telescope. The somewhat brighter stars HIP 53881 and 52 Leonis can assist in your search.
Saturday, October 22 – Saturn Pauses Close to Star Iota Cap (evening)
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On Saturday night, October 22, Saturn’s westward retrograde motion through the stars of central Capricornus will slow to a stop as it completes a retrograde loop that it began in early June. This evening, Saturn’s magnitude 0.6 yellowish dot will appear in the lower part of the southwestern sky, shining less than a finger’s width to the upper left (or 0.6 degrees to the celestial northeast) of the bright star Iota Capricorni — close enough to share the view in a backyard telescope (green circle). As Saturn resumes its regular prograde motion in the coming weeks, it will widen its separation east of that star.
Sunday, October 23 – Morning Zodiacal Light for Mid-Northern Observers (pre-dawn)
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During autumn at mid-northern latitudes every year, the ecliptic (green line) extends nearly vertically upward from the eastern horizon before dawn. That geometry favors the appearance of the faint zodiacal light in the eastern sky for about half an hour before dawn on moonless mornings. Zodiacal light is sunlight scattered by interplanetary particles that are concentrated in the plane of the solar system — the same material that produces meteor showers. It is more readily seen in areas free of urban light pollution. Between now and the full moon on November 8, look for a broad wedge of faint light extending upwards from the eastern horizon and centered on the ecliptic. It will be strongest in the lower third of the sky, below the bright star Regulus. Try taking a long exposure photograph to capture the zodiacal light, but don’t confuse it with the Milky Way, which is positioned nearby in the southern sky.
Monday, October 24 – Very Old Moon Meets Mercury (before sunrise)
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Just above the eastern horizon before sunrise on Monday, October 24, the very old crescent moon (only 1% illuminated) will shine less than a thumb’s width above (or 1.6 degrees to the northwest of) the bright planet, Mercury. The duo will be tough to see within the pre-dawn twilight. Binoculars (green circle) will help your search — but be sure to turn them away before the sun rises. The optimal viewing window at mid-northern latitudes will be 6:30 to 6:50 a.m. local time.
Tuesday, October 25 – New Moon and Partial Solar Eclipse (at 10:49 GMT)
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The moon will officially reach its new phase at 6:49 a.m. EDT, 3:49 a.m. PDT, or 10:49 GMT on Tuesday, October 25. This new moon will also feature a deep partial solar eclipse that will be visible across most of Europe, northeastern Africa and the Middle East, and Central Asia. After the moon’s penumbral shadow first contacts Earth in the North Atlantic Ocean around sunrise at 08:58:20 GMT, it will sweep eastward and south across Europe and the Middle East until it lifts off Earth near the Persian Gulf at 13:02:16 GMT. The instant of greatest eclipse, with the moon blocking 0.63 of the sun’s diameter, will occur east of Surgut, Russia, around sunset, at 11:01:20 GMT. This solar eclipse will be followed by a total lunar eclipse on Nov 8. Protective solar filters will be needed to view any part of this eclipse.
Wednesday, October 26 – Double Shadow Transit on Jupiter (20:20 to 22:20 GMT)
On Wednesday evening, October 26 observers with telescopes across Africa, Europe, and western Asia can watch the round black shadows of two of Jupiter’s moons cross the southern hemisphere of the giant planet together for two hours. At 10:20 p.m. CEST or 20:20 GMT, the large shadow of Ganymede will join Europa’s smaller shadow, which began to cross at 9:55 p.m. CEST. Europa’s shadow will move off Jupiter at 12:20 a.m. CEST or 22:20 GMT, leaving Ganymede’s shadow to cross alone until 1 a.m. CEST or 23:00 GMT.
Thursday, October 27 – Young Moon near Antares (after sunset)
Low in the southwestern sky after dusk on Thursday, October 27, the young crescent moon will shine beside the claw stars of Scorpius, several finger-widths to the right (or 4 degrees to the celestial northwest) of the scorpion’s bright, reddish star Antares. They will be close enough to share the view in binoculars (green circle). Scorpius’ stars will become easier to see as the sky darkens, but the tableau will disappear below the rooftops by about 7 p.m. local time.
Saturday, October 29 – Mars Enters Retrograde (overnight)
On Saturday night, October 29 in the Americas, Mars’ eastward prograde motion through the stars of Taurus will slow to a stop in order for it to begin a westerly retrograde loop that will last through its December opposition and into mid-January. On Saturday evening, bright, reddish Mars will be positioned in the eastern sky between the two horn tips of the bull, the medium-bright stars Zeta Tauri and Elnath. Over the next month, you can watch Mars swing between those stars and then race west (red path with date:hr) towards the bright Pleiades star cluster.
Sunday, October 30 – Medusa’s Eye Pulses (at 01:39 GMT)
In the constellation of Perseus, Algol, also designated Beta Persei, marks the glowing eye of Medusa from Greek mythology. The star is among the most accessible variable stars for skywatchers. During a ten-hour period that repeats every 2 days, 20 hours, and 49 minutes, Algol dims noticeably and re-brightens because a companion star orbiting nearly edge-on to Earth crosses in front of the much brighter main star, reducing the total light output we perceive. Algol normally shines at magnitude 2.1, similar to nearby Almach in Andromeda. But when fully dimmed, Algol’s magnitude 3.4 is slightly fainter than Rho Persei (ρ Per), the star sitting just two finger widths to Algol’s lower right (or 2.25 degrees to the celestial south). On Sunday, October 30 at 9:39 p.m. EDT or 6:39 p.m. PDT, Algol will be at its minimum brightness. At that time it will be located in the lower part of the northeastern sky. Five hours later the star will return to full intensity from a perch nearly overhead.
Monday, October 31 – The Spooky Owl Cluster (all night)
One of my favorite spooky objects can be seen in binoculars or a backyard telescope on autumn evenings. It’s one of the many bright, open star clusters in the W-shaped of Cassiopeia, the Queen, which you’ll find in the northeastern sky. NGC 457, better known as the Owl Cluster, ET Cluster, or Dragonfly Cluster, is dominated by two prominent, close-together, yellow stars (Phi Cas and HD 7902) that form the eyes, a sprinkling of dimmer stars for the body and feet, and two curved chains of stars that look like upswept wings. Be aware that the critter is positioned with its head pointing away from Cassiopeia, which circles the north celestial pole. The cluster occupies the 90-degree corner of a right-angle triangle that is completed by the stars Gamma Cas and Ruchbah. It’s about two finger widths above (or 2 degrees to the celestial south-southwest of) Ruchbah — as if the queen is bouncing the baby owl on her knee!
Planets
Mercury
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Mercury will begin October shining at magnitude 1.2 in the eastern pre-dawn sky. The swift planet will increase its angle from the sun until it reaches a maximum elongation of 18 degrees, and peak visibility, on October 8. The best views of the planet then will fall between about 6 and 6:30 am local time. After maximum elongation, Mercury will sink sunward again. The early October apparition will be the best of the year for observers at mid-northern latitudes, but a poor one for those in the southern hemisphere. The planet will steadily increase in brightness during October. Viewed in a telescope, Mercury will wax in the illuminated phase from 18% to 99% while its apparent disk diameter halves from 8.8 to 4.8 arc-seconds. (Be sure to turn all optical aids away from the eastern horizon before the sun rises.) By the time the old crescent moon appears a thumb’s width above (to the celestial northwest) Mercury on October 24, the planet will have become very difficult to see.
Venus
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During the first few mornings of October, Venus might be spotted with difficulty just above the eastern horizon before sunrise. The very bright planet will sink sunward each morning, pass the sun at superior conjunction on October 21, and then re-appear in the western evening sky towards year-end.
Mars
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Mars will be well positioned for viewing starting in the late evenings during October. On the 1st it will rise just after 10 p.m. local time and climb high in the southern sky by sunrise. By the month’s end, Mars’ rising time will advance to 8:20 p.m. local time. The red planet will spend October slowing its eastward trek between the horns of Taurus. On October 30 Mars will cease its motion altogether and then begin a westerly retrograde loop that will last through a fine opposition in early December and then end in mid-January. Over the month, Earth’s distance from Mars will decrease by 13.67 million miles (22 million km). As a result, Mars will brighten from magnitude -0.59 to -1.22. Its appearance in telescopes will show a nearly fully illuminated disk that swells in apparent diameter from 12 to 15 arc-seconds. Watch for suggestions of the dark markings that will become clearer at opposition. Mars will pass only 1.2 degrees to the north of the Crab Nebula supernova remnant from October 14-16; but the bright, waning gibbous moon will shine nearby to their north.
Jupiter
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Jupiter will be well-placed for observing all night long during October — although it will be highest, and look sharpest in telescopes, during the middle hours of the night. The planet will continue its slide westward across the stars of western Pisces — and towards Neptune. Its separation from that distant, blue planet will decrease from 9 to 6.8 degrees. The yellowish dot of 24 times less bright Saturn will shine about 40 degrees to Jupiter’s southwest. Still only weeks past its closest opposition in decades, Jupiter will shine at a very bright magnitude of -2.9. In amateur telescopes, the planet will exhibit equatorial bands girdling a generous, 49 arc-seconds-wide disk, the Great Red Spot will appear every second or third night, and Jupiter’s four large Galilean satellites will frequently eclipse and occult one another, and cast their round, black shadows on the planet — singly and in pairs. The nearly full moon will hop past Jupiter on October 7-8.
Saturn
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During October, the yellowish dot of Saturn will be observable from after dusk until late evening — though it won’t climb very high when it culminates in the southern sky in mid-evening. The white dot of 24 times brighter Jupiter will be positioned 40 degrees to Saturn’s left (or celestial east). On October 23 Saturn will cease its westerly retrograde motion and prepare to resume regular eastward prograde motion. That same night Saturn will approach to within 0.6 degrees east of the magnitude 4.2 star Iota Capricorni in central Capricornus. Their separation will noticeably widen over the following weeks. Viewed in a telescope during October, Saturn will show an apparent disk diameter of 17.7 arc-seconds, and its rings will subtend 41 arc-seconds. Saturn’s rings will be tilting more edge-on to us every year until the spring of 2025. This year they are already closed enough for Saturn’s southern polar region to extend well beyond them. The waxing gibbous moon will shine to the southeast of Saturn on October 5.
Uranus
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Blue-green Uranus will be observable between late evening and dawn during October. Rising shortly after 8 p.m. local time on the 1st, Uranus will climb highest in the southern sky, and look best in telescopes, during the wee hours. By month’s-end, those timings will advance by 2 hours. Over the month, magnitude 5.6 Uranus will travel retrograde westward through the stars of southeastern Aries. Its trajectory will be parallel to, and about 1.5 degrees to the south of, the line joining the brighter stars Botein (Delta Arietis) and Pi Arietis, creating a triangular asterism for anyone searching for Uranus in binoculars. Uranus’ small, 3.8 arc-seconds-wide blue disk will appear markedly different from those stars. On October 11, the bright, waning gibbous moon will shine 2 degrees to the upper right (or celestial WSW) of Uranus. Hours later, observers with telescopes in Alaska, northwestern continental USA, and northern and western Canada, and Greenland can see the moon occult Uranus around 05:00 to 06:00 GMT — the tenth in a series of consecutive lunar occultations of that planet.
Neptune
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During October, the distant, blue planet Neptune will be an all-night target that will share the sky with far brighter Jupiter to its east and the yellowish dot of Saturn shining 35 degrees to the southwest. The Jupiter-Neptune separation will decrease from 9 to 6.8 degrees over the month. Neptune will shine at magnitude 7.8, which is within reach of good binoculars. The blue planet will be traveling retrograde westward among the stars of northeastern Aquarius, towards the medium-bright star Phi Aquarii. In a telescope, Neptune’s tiny apparent disk size will span 2.4 arc-seconds. Larger telescopes can show Neptune’s large moon Triton.
Skywatching terms
Gibbous: Used to describe a planet or moon that is more than 50% illuminated.
Asterism: A noteworthy or striking pattern of stars within a larger constellation.
Degrees (measuring the sky): The sky is 360 degrees all the way around, which means roughly 180 degrees from horizon to horizon. It’s easy to measure distances between objects: Your fist on an outstretched arm covers about 10 degrees of sky, while a finger covers about one degree.
Visual Magnitude: This is the astronomer’s scale for measuring the brightness of objects in the sky. The dimmest object visible in the night sky under perfectly dark conditions is about magnitude 6.5. Brighter stars are magnitude 2 or 1. The brightest objects get negative numbers. Venus can be as bright as magnitude minus 4.9. The full moon is minus 12.7 and the sun is minus 26.8.
Terminator: The boundary on the moon between sunlight and shadow.
Zenith: The point in the sky directly overhead.
Night sky observing tips
Adjust to the dark: If you wish to observe fainter objects, such as meteors, dim stars, nebulas, and galaxies, give your eyes at least 15 minutes to adjust to the darkness. Avoid looking at your phone’s bright screen by keeping it tucked away. If you must use it, set the brightness to minimum – or cover it with clingy red film.
Light Pollution: Even from a big city, one can see the moon, a handful of bright stars, and the brightest planets – if they are above the horizon. But to fully enjoy the heavens — especially a meteor shower, the fainter constellations, or to see the amazing swath across the sky that is the disk of our home galaxy, the Milky Way — rural areas are best for night sky viewing. If you’re stuck in a city or suburban area, use a tree or dark building to block ambient light (or moonlight) and help reveal fainter sky objects. If you’re in the suburbs, simply turning off outdoor lights can help.
Prepare for skywatching: If you plan to be outside for more than a few minutes, and it’s not a warm summer evening, dress more warmly than you think is necessary. An hour of winter observing can chill you to the bone. For meteor showers, a blanket or lounge chair will prove to be much more comfortable than standing, or sitting in a chair and craning your neck to see overhead.
Daytime skywatching: On the days surrounding first quarter, the moon is visible in the afternoon daytime sky. At last quarter, the moon rises before sunrise and lingers into the morning daytime sky. When Venus is at a significant angle away from the sun it can often be spotted during the day as a brilliant point of light – but you’ll need to consult an astronomy app to know when and where to look for it. When large sunspots develop on the sun, they can be seen without a telescope – as long as you use proper solar filters, such as eclipse glasses. Permanent eye damage can occur if you look at the sun for any length of time without protective eyewear.
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