Wednesday, Oct. 1 — Crater Copernicus (all night)
For several nights starting on Wednesday, Oct. 1, conditions will be particularly good for viewing the prominent crater Copernicus, which is located in eastern Oceanus Procellarum, the broad dark region south of Mare Imbrium and slightly northwest of the moon’s centre.
Copernicus’ 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 full moon, Copernicus’ ray system, extending 500 miles (800 kilometers) in all directions, becomes prominent.
Thursday, Oct. 2 — Ceres at opposition (all night)
On Thursday, Oct. 2, the dwarf planet Ceres will reach opposition, the time when it is closest to Earth for the year at a distance of 182 million miles (293 million km) or 16.3 light-minutes. On the nights around opposition, this largest resident of the main asteroid belt between Mars and Jupiter will reach a peak brightness of magnitude 7.65, which is within reach of binoculars (orange circle) and backyard telescopes.
Tonight, Ceres will be located two finger widths to the upper right (or 2.6 degrees to the celestial west) of the medium-bright star Eta Ceti in Cetus, with far brighter Saturn shining well to the upper right. Ceres will ascend the southeastern sky during evening, and then reach its highest elevation and best observing position when due south around 1 a.m. local time. It will spend the rest of October travelling west (red path) above Cetus’ bright tail star Deneb Kaitos (Beta Ceti).
Friday, Oct. 3 — Crater Kepler (evening)
Kepler is a small but prominent impact crater located to the west of the much larger crater Copernicus in the vast dark plain of Oceanus Procellarum. While only 20 miles (32 km) in diameter, it is obvious to the unaided eye and with binoculars. It is encircled by an extensive ring of ejecta and rays that resemble Copernicus’ in nature. Almost any amount of magnification will reveal Kepler’s sharp-edged, polygonal rim, some terracing around the interior wall, and a complex floor with a minor central peak.
Sunday, Oct. 5 — Bright moon shines near Saturn and Neptune (all night)
When the bright, nearly-full moon clears the eastern rooftops after sunset on Sunday, Oct. 5, the yellowish dot of Saturn will shine prominently below it (i.e., to its celestial SSE). Neptune will be positioned a few finger widths to Saturn’s left, allowing all three objects to share the view in binoculars (orange circle) — but the faint remote planet will be all but invisible against the moon’s glare. For skywatchers viewing the scene later at night or in more westerly time zones, the moon’s eastward orbital motion will shift it closer to Neptune and farther from Saturn. Meanwhile, the diurnal rotation of the sky will shift Saturn below the moon by the time they set in the west before dawn.
Monday, Oct. 6 — Full Harvest Supermoon
The full moon of October will occur on Monday, Oct. 6 at 11:48 p.m. EDT (8:48 p.m. PDT, which converts to 0348 GMT on Tuesday, Oct. 7). This full moon is traditionally called the Hunter’s Moon or Sanguine Moon.
The Anishinaabe people of the Great Lakes region call it 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 use Kentenha, the Time of Poverty Moon.
Full moons in October always shine in or near the stars of Cetus and Pisces. With the moon passing perigee only 1.5 days later, this full moon will also be the first and smallest of three consecutive supermoons in 2025. It will appear about 4% larger and 13% brighter than an average full moon (shown by the red circle), cross the sky from sunset to sunrise, and will produce large tides around the world. Because this full moon occurs nearest to the autumnal equinox in 2025, it is also the Harvest Moon.
On the evenings around its full phase, the moon normally rises about 50 minutes later than the previous night. But the shallow slope of the evening ecliptic (and the moon’s orbit) around the equinox causes Harvest Moons to rise at almost the same time each night — only delayed by as little as 10 minutes, depending on your latitude. This phenomenon traditionally allowed farmers to work into the evening under bright moonlight — hence the name.
Thursday, Oct. 9 — Bright moon kisses the Seven Sisters (overnight)
When the still very full and bright, waning gibbous moon rises over the eastern rooftops at about 9 p.m. local time on Thursday evening, Oct. 9, the bright star cluster known as the Pleiades, the Seven Sisters, the Hole in the Sky, Matariki, and Messier 45 will be sparkling several finger widths to its lower left — close enough for them to share the view in binoculars (orange circle).
To better see the cluster’s stars, which are spread over an area nearly four times larger than the moon, hide the moon beyond the upper right edge of your binoculars’ field of view. Skywatchers viewing the scene later at night, and in more westerly time zones, will see the moon approach closer to the cluster, pass among its stars around 04:00 GMT on Friday, and then move off to their east (red path). The faint blue speck of Uranus is positioned less than a palm’s width to the lower right (or 4 degrees to the celestial SSE) of the Pleiades this month.
Friday, Oct. 10 — Subtle wrinkles on Nectaris and Tranquillitatis (overnight)
On Friday evening, Oct. 10, in the Americas, the terminator on the waning gibbous moon will fall just to the east of the round, dark Mare Nectaris. Use binoculars or a backyard telescope to see subtle wrinkles that curve around the surface of its dark basalt. Others appear on Mare Tranquillitatis to its north. Such subtleties are revealed when slanted sunlight casts shadows from small elevation changes.
Sunday, Oct. 12 — Medusa’s eye pulses
The star Algol, also designated Beta Persei, marks the glowing eye of Medusa from Greek mythology. This star in the constellation of Perseus 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 by about a third while a fainter companion star with an orbit nearly edge-on to Earth crosses in front of its much brighter primary, reducing the total light output we perceive.
Algol normally shines at magnitude 2.1, similar to the nearby star Almach (aka Gamma Andromedae). But when fully dimmed, Algol’s brightness of magnitude 3.4 is almost identical to Rho Persei (or Gorgonea Tertia or ρ Per), the star sitting just two finger widths to Algol’s lower right (or 2.25 degrees to the celestial south). On October evenings, Perseus is climbing the northeastern sky after dusk. On Sunday evening, Oct. 12, Algol will begin to decrease in brightness at 7:42 p.m. EDT (2342 GMT). Five hours later at 12:42 a.m. EDT (0442 GMT), the star will have faded to its minimum while it shines nearly overhead in the eastern sky.
Monday, Oct. 13 — Third quarter moon near Jupiter
The moon will complete three-quarters of its orbit around Earth, measured from the previous new moon, on Monday, Oct. 13 at 2:13 p.m. EDT (11:13 a.m. PDT, 1813 GMT). At the third (or last) quarter phase, the moon always appears half-illuminated, on its western, sunward side. When this month’s third quarter moon rises in the east around midnight local time, the very bright planet Jupiter will be gleaming to its right — close enough for them to share the view in binoculars (orange circle) by observers in eastern North America.
By sunrise, the planet will be farther from the moon and positioned to its right. The week of dark, moonless evenings that follow this phase is the best time for observing fainter deep sky targets.
Wednesday, Oct. 15 — The Andromeda Galaxy (all night)
In mid-October, the Andromeda Galaxy is climbing in the eastern sky in the evening. This large spiral galaxy, also designated Messier 31 and NGC 224, is 2.5 million light-years from us, and covers an area of sky measuring 3 by 1 degrees (or six by two full moon diameters)!
Under dark skies, M31 can be seen with unaided eyes as a faint smudge located 1.4 fist diameters to the left (or 14 degrees to the celestial northeast) of Alpheratz, the star that forms the left-hand (northwestern) corner of the square of Pegasus. The three westernmost stars of Cassiopeia, Caph, Shedar, and Navi (Gamma Cas), also conveniently form an arrow that points towards M31.
Binoculars will reveal the galaxy better. In a telescope, use low magnification and look for M31’s two smaller companion galaxies, the foreground Messier 32 and the more distant Messier 110 (inset).
Thursday, Oct. 16 — Crescent moon and Regulus between Jupiter and Venus (predawn)
Early risers on Thursday morning, Oct. 16, can enjoy the sight of the pretty, waning crescent moon shining in the eastern sky above Leo’s brightest star, Regulus. The extremely bright planet Jupiter will be perched above them and even brighter Venus will rise to join the party from about 5:30 a.m. local time until sunrise.
Friday, Oct. 17 — Predawn Earthshine moon over Venus
On the mornings surrounding Friday, Oct. 17, the old crescent moon will shine low in a twilit eastern sky above brilliant Venus before sunrise. Watch for Earthshine, also known as the Ashen Glow and “the old moon in the new moon’s arms”. That’s sunlight reflected off Earth and back onto the moon, slightly brightening the dark portion of the moon’s Earth-facing hemisphere. The phenomenon appears for several days before and after each new moon. Since the Earthshine light has made an extra round trip from Earth to the moon and back, it is about 2.6 seconds “older” than the the light we see from the lit crescent.
Saturday, Oct. 18 — Watch Algol brighten
On Saturday evening, Oct. 18, the variable star Algol in Perseus will display its minimum brightness while it shines a small distance above the northeastern horizon after dusk. At 6:19 p.m. EDT (2219 GMT), its magnitude of 3.4 will be similar to the star Rho Persei (or Gorgonea Tertia or ρ Per), which shines just two finger widths to Algol’s lower right (or 2.25 degrees to the celestial south).
Algol will steadily brighten while it climbs the eastern sky, returning to full intensity at 11:19 p.m. EDT (0319 GMT), when it will match the star Almach sitting about a fist’s diameter above it. Both stars will be high in the east above and between the very bright stars Capella and Aldebaran.
Sunday, Oct. 19 — Morning Zodiacal Light (predawn)
During autumn at mid-northern latitudes every year, the ecliptic 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. The phenomenon is more readily seen in areas free of urban light pollution. Between now and the full moon on Nov. 5, look for a broad wedge of faint light extending upwards from the eastern horizon and centered on the ecliptic (the green line). It will be strongest in the lower third of the sky around the bright star Regulus in Leo. Don’t confuse the zodiacal light with the Milky Way, which is positioned nearby in the southeastern sky.
Sunday, Oct. 19 — Old moon and Venus (before sunrise)
Low in the eastern sky as dawn breaks on Sunday, Oct. 19, the old, waning moon’s slender crescent will form a lovely photo opportunity while it poses just to the upper right of the brilliant planet Venus. While both objects will hold a similar angle away from the morning sun, Venus’ position on the far side of its orbit beyond the sun will give it an almost fully illuminated phase (inset).
Monday, Oct. 20 — Mercury zips past Mars (after sunset)
For about a week surrounding Monday, Oct. 20, the motion of speedy Mercury will carry it past Mars. The duo will share the view in binoculars (orange circle) in a twilight sky just above the southwestern horizon for a short time after the sun sets every night. On the evenings leading up to Monday, Mercury’s brighter dot will be located 2-3 degrees below (or celestial south of) fainter reddish Mars. After Monday, Mercury will move farther to the lower left of Mars. Their meeting will be best observed from the tropics and farther south, where the two planets will be higher and in a darker sky.
Tuesday, Oct. 21 — Orionids Meteor Shower peak (predawn)
The annual Orionids meteor shower is produced when the Earth passes through a cloud of small particles dropped by repeated passages of Comet Halley along its orbit. Viewed in a dark sky during the peak of the shower, 10 to 20 bright and fast-moving meteors are usually seen each hour. Although this shower is active from Sept. 26 to around Nov. 22, it will peak in the Americas on the morning of Tuesday, Oct. 21, when Earth will be crossing the densest region of the particle field. The moon at new will not bother the shower at all this year. Start watching for Orionids after dusk on Monday night. Orionid meteors will appear anywhere in the sky, but they can be traced back to their radiant in the constellation of Orion. Somewhat fewer meteors can be seen on the surrounding nights.
Tuesday, Oct. 21 — New moon
The moon will pass the sun at new moon on Tuesday, Oct. 21 at 8:25 a.m. EDT (5:25 a.m. PDT, or 1225 GMT). At that time, our natural satellite will be 3.8 degrees south of the sun in Virgo. While new, the moon is traveling between Earth and the sun. Since sunlight can only illuminate the far side of the moon, and the moon is in the same region of the sky as the sun, it is usually completely hidden from view from anywhere on Earth for about a day (unless there is a solar eclipse).
Thursday, Oct. 23 — Crescent moon Lines up with Mercury and Mars (after sunset)
After sunset on Thursday, Oct. 23, the slender crescent of the young moon will line up with Mercury and Mars just above the west-southwestern horizon. Their meeting will be a challenge to see from mid-northern latitudes due to bright twilight and haze, but binoculars (orange circle) can be used once the sun has fully set. For skywatchers located in the tropics and farther south, the moon and planets will be higher and in a darker sky.
Friday, Oct. 24 — Young moon near Antares (after sunset)
As the sky darkens after sunset on Friday, Oct. 24, the waxing crescent moon will be positioned a thumb’s width below (or 2 degrees to the celestial southwest of) the star that marks the heart of the Scorpion, bright reddish Antares. The pair will make a lovely sight in binoculars (orange circle) as they sink in the southwestern sky. Sharp eyes might catch Mercury and Mars off to their right. Observers in an area from the southern tip of South America to Antarctica can use eyes, binoculars, or telescopes to safely watch the moon occult Antares around 02:00 GMT on Oct. 25.
Sunday, Oct. 26 — The Dolphin swims the southern sky (all night)
During mid-evening in late 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 very 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 backwards. Gamma Delphinus, the star marking the dolphin’s nose, is a close-together double star with one component a greenish colour.
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.
Tuesday, Oct. 28 — Lunar X in early evening
Several times a year, for a few hours near the moon’s first quarter phase, patterns on the moon called the Lunar X and Lunar V become visible in strong binoculars and backyard telescopes.
The Lunar X is located on the terminator south of the crater La Caille, about one third of the way up from the southern pole of the moon (at 2° East, 24° South).
The “V” is located near the crater Ukert (at 1° East, 14° North). On Tuesday, Oct. 28, those letter shapes are predicted to start developing by 5 p.m. EDT (2100 GMT), peak in intensity around 7 p.m. EDT (2300 GMT), and then gradually fade out. That peak will be during waning daylight for observers in the eastern Americas — but you can observe the moon in a telescope during daytime, as long as you take care to avoid the sun. The Lunar X and V will be observable anywhere on Earth where the moon is visible, especially in a dark sky, between about 2100 GMT on Oct. 28 and 0100 GMT on Oct. 29.
Wednesday, Oct. 29 — First Quarter moon
The moon will complete the first quarter of its journey around Earth on Wednesday, Oct. 29, at 12:21 p.m. EDT (9:21 a.m. PDT or 1621 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. At first quarter, the moon always rises around midday and sets around midnight, so it is also visible in the daytime sky. The evenings surrounding the first quarter are the best ones for seeing the lunar terrain when it is dramatically lit by low-angled sunlight, especially along the terminator, the pole-to-pole boundary that separates the lit and dark hemispheres.
Wednesday, Oct. 29 — Mercury at greatest eastern elongation (after sunset)
On Wednesday, Oct. 29, Mercury (orbit shown in red) will reach its widest separation of 24 degrees east of the sun and maximum visibility for its current evening apparition. With Mercury positioned well below (i.e., south of) the tilted evening ecliptic (green line) in the southwestern sky, this appearance of the planet will be a poor one for Northern Hemisphere observers, but a very good showing from the tropics and the Southern Hemisphere.
The optimal viewing times at mid-northern latitudes will start around 6 p.m. local time. Viewed in a telescope (inset), the planet will exhibit a waning, slightly gibbous phase. The much fainter planet Mars will be positioned almost a palm’s width (5 degrees) to Mercury’s right (or celestial WNW).
Thursday, Oct. 30 — The spooky Owl Cluster (all night)
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 (inset). The critter is positioned with its head pointing away from Cassiopeia, which circles the north celestial pole, so it rotates through the night. 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!
Friday, Oct. 31 — Mare Imbrium’s Golden Handle (all night)
On Friday night, Oct. 31, the terminator on the waxing gibbous moon will cross Sinus Iridum, the Bay of Rainbows. The circular 155-mile (249 km) diameter feature is a large impact crater that was flooded by the same basalts that filled the much larger Mare Imbrium to its east — forming a rounded “handle” on the western edge of that mare.
The “Golden Handle” effect is produced when sunlight strikes the prominent Montes Jura mountain range surrounding Sinus Iridum on the north and west while the floor of the bay remains dark. Sinus Iridum is almost craterless, but hosts a set of northeast-oriented wrinkle ridges that are revealed around this phase.
Read more at: https://www.space.com/16149-night-sky.html