October Celestial Calendar by Dave Mitsky
All times, unless otherwise noted, are UT (subtract four hours and, when appropriate, one calendar day for EDT)
10/1 The Moon is 3.5 degrees south of the bright open cluster M35 in Gemini at 22:00
10/2 Last Quarter Moon occurs at 9:45
10/3 The Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to be visible at 7:00; the Moon is 7.5 degrees south of the first-magnitude star Pollux (Beta Geminorum) at 11:00
10/4 The Moon is at the ascending node (longitude 123.5 degrees) at 3:11; the Moon is 1.2 degrees south of the bright open cluster M44 (the Beehive Cluster or Praesepe) in Cancer at 10:00
10/5 Venus is stationary in right ascension, with retrograde (westward) motion to commence, at 4:00; Mercury is 2.0 degrees north of the first-magnitude star Spica (Alpha Virginis) at 18:00; Venus is stationary in longitude at 19:00; the Moon is at perigee, subtending 32′ 37″ from a distance of 366,392 kilometers (227,666 miles), at 22:27; the Moon is 1.8 degrees north-northeast of the first-magnitude star Regulus (Alpha Leonis) at 23:00
10/6 Mercury is at the descending node through the ecliptic at 0:00; 9 Mercury (magnitude -0.6) is 2.0 degrees north-northeast of Spica at 9:00
10/7 The dwarf planet/asteroid 1 Ceres is in conjunction with the Sun at 10:00
10/8 The peak of the Draconid meteor shower (10 to 30 per hour) occurs at 15:00
10/9 New Moon occurs (lunation 1185) at 3:47; the Moon is 7.0 degrees north-northeast of Spica at 18:00
10/10 The Moon is 5.5 degrees north-northeast of Mercury at 4:00
10/11 The Moon is 3.9 degrees north-northeast of Jupiter at 23:00
10/13 The Moon is 8.6 degrees north of Antares (Alpha Scorpii) at 6:00
10/15 The Moon 1.8 degrees north of Saturn at 3:00; the winter solstice occurs in the northern hemisphere of Mars at 21:00
10/16 Venus (magnitude -4.3) is 6.2 degrees south-southwest of Mercury (magnitude -0.3) at 3:00; Mercury is at aphelion (0.4667 a.u. from the Sun) at 9:00; asteroid 3 Juno is stationary at 18:00; First Quarter Moon occurs at 18:02; the Lunar X, also known as the Purbach or Werner Cross, an X-shaped illumination effect involving various rims and ridges between the craters La Caille, Blanchinus, and Purbach, is predicted to be visible at 19:22; sunrise takes place at the isolated lunar mountain Mons Pico at 21:28
10/17 Moon at descending node (longitude 302.2 degrees) at 12:08; sunrise takes place at the isolated lunar mountain Mons Piton at 12:19; the Moon is at apogee, subtending 29′ 34″ from a distance of 404,227 kilometers (251,175 miles), at 19:16
10/18 The Moon is 1.9 degrees north-northwest of Mars at 12:00
10/20 Saturn is at greatest declination south (-22.8 degrees) at 20:00; the Moon is 3.0 degrees south of Neptune at 22:00
10/21 The peak of the Orionid meteor shower (15 per hour) occurs at 18:00
10/24 Uranus is at opposition (magnitude +5.7, apparent size 3.7″) at 1:00; the Moon is 4.4 degrees south-southeast of Uranus at 16:00; Full Moon, known as the Blood or Sanguine Moon and this year’s Harvest Moon, occurs at 16:45
10/25 Pluto is at the descending node through the ecliptic plane at 20:00
10/26 Venus is in inferior conjunction with the Sun (0.272 a.u. from the Earth and 6.26 degrees south of the Sun) at 14:00; the Moon is 8.4 degrees south-southeast of the bright open cluster M45 (the Pleiades or Subaru) in Taurus at 21:00
10/27 The Moon is 1.6 degrees north of Aldebaran (Alpha Tauri) at 13:00
10/29 The Moon is 3.3 degrees south of M35 at 4:00; Mercury (magnitude -0.2) is 3.1 degrees south-southwest of Jupiter (magnitude -1.7) at 7:00
10/30 The Moon is 7.3 degrees south of Pollux at 17:00
10/31 The Moon at ascending node (longitude 120.6 degrees) at 3:46; the Sun enters Libra (longitude 217.80 degrees on the ecliptic) at 7:00; the Moon is 0.68 degree south of M44 (the Beehive Cluster or Praesepe) at 16:00; Last Quarter Moon occurs at 16:41; the Moon is at perigee, subtending 32′ 17″ from a distance of 370,204 kilometers (230,034 miles), at 20:23
Ejnar Hertzsprung and Henry Norris Russell were born this month.
The first recorded solar eclipse took place on October 22, 2136 BCE. Supernova SN 1604 (Kepler’s Supernova) became visible to the naked-eye on October 9, 1604. Giovanni Cassini discovered Saturn’s odd satellite Iapetus on October 25, 1671. M51a (the Whirlpool Galaxy) was discovered by Charles Messier on October 13, 1773. William Lassell discovered Triton, Neptune’s brightest satellite, on October 10, 1846. Maria Mitchell discovered Comet C/1847 T1 (Miss Mitchell’s Comet) on October 1, 1847. Asteroid 8 Flora was discovered by John Russell Hind on October 18, 1847. Two of the satellites of Uranus, Ariel and Umbriel, were discovered by William Lassell on October 24, 1851. Edwin Hubble discovered Cepheid variable stars in M31 (the Andromeda Galaxy) on October 5, 1923. Charles Kowal discovered 2060 Chiron, the first Centaur asteroid, on October 18, 1977. Michel Mayor and Didier Queloz announced the discovery of the exoplanet 51 Pegasi b (Dimidium) on October 6, 1995.
The Draconid (formerly the Giacobinid) meteor shower peaks on the night of October 8th/9th. The Draconids are quite variable and have produced meteor storms in 1933 and 1946. Comet 21P/Giacobini-Zimmer is the parent comet of the Draconids. Since this periodic comet reached perihelion in September, an outburst may be possible. Consult http://earthsky.org/astronomy-essentials/everything-you-need-to-know-draconid-meteor-shower for additional information on the Draconid meteor shower. The Southern Taurid shower, debris from Comet 2P/Encke, may produce five meteors per hour when it peaks on October 10th. The Orionid meteor shower peaks on the night of October 21st but is compromised by a 91%-illuminated waxing gibbous Moon. However, there will be a two-hour window of darkness before morning twilight begins. Orionid meteors are fragments of Comet 1P/Halley. Browse http://www.timeanddate.com/astronomy/meteor-shower/orionid.html or http://earthsky.org/astronomy-essentials/everything-you-need-to-know-orionid-meteor-shower for more on the Orionids.
Information on Iridium flares and passes of the ISS, the Tiangong-2, the USAF’s X-37B, the HST, and other satellites can be found at http://www.heavens-above.com/
The zodiacal light may be visible in the pre-dawn eastern sky from a dark site, assuming that there is no moonlight present. Articles on the zodiacal light appear at http://www.atoptics.co.uk/highsky/zod1.htm and http://earthsky.org/astronomy-essentials/everything-you-need-to-know-zodiacal-light-or-false-dawn
The Moon is 21.1 days old, subtends 31.5 arc minutes, is illuminated 67.5%, and is located in Pisces on October 1st at 0:00 UT. The Moon reaches its greatest northern declination (+21.3 degrees) on October 30th and its greatest southern declination (-20.9 degrees) on October 15th. Longitudinal libration is at a maximum of +6.1 degrees on October 12th and a minimum of -4.8 degrees on October 24th. Latitudinal libration is at a maximum of +6.6 degrees on October 25th and a minimum of -6.5 degrees on October 10th. New Moon occurs on October 9th. The Moon is at apogee (a distance of 63.38 Earth-radii) on October 17th and at perigee (a distance of 57.45 Earth-radii) on October 5th and again (a distance of 58.05 Earth-radii) on October 31st. Consult http://www.lunar-occultations.com/iota/planets/planets.htm and http://www.lunar-occultations.com/iota/bstar/bstar.htm for further information on lunar occultation events. Visit http://saberdoesthestars.wordpress.com/2011/07/05/saber-does-the-stars/ for tips on spotting extreme crescent Moons and http://www.curtrenz.com/moon06.html for Full Moon data. Times and dates for the lunar light rays predicted to occur in October are available at http://www.lunar-occultations.com/rlo/rays/rays.htm
The Sun is located in Virgo on October 1st at 0:00 UT. It enters Libra at 0:00 UT on October 31st.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on October 1st: Mercury (magnitude -0.9, 4.8″, 98%, 1.41 a.u., Virgo), Venus (magnitude -4.8, 46.2″, 17%, 0.36 a.u., Virgo), Mars (magnitude -1.3, 15.8″, 88%, 0.59 a.u., Capricornus), Jupiter (magnitude -1.8, 32.6″, 100%, 6.05 a.u., Libra), Saturn (magnitude +0.5, 16.5″, 100%, 10.10 a.u., Sagittarius), Uranus (magnitude +5.7, 3.7″, 100%, 18.88 a.u. on October 16th, Aries), Neptune (magnitude +7.8, 2.3″, 100%, 29.15 a.u. on October 16th, Aquarius), and Pluto (magnitude +14.2, 0.1″, 100%, 33.72 a.u. on October 16th, Sagittarius).
This month Mercury, Venus, Jupiter, and Saturn are located in the southwest, Mars in the south, and Uranus in the east, and Neptune in the southeast during the evening. At midnight, Mars, Uranus, and Neptune can be found in the south. Uranus is in the west in the morning sky.
Mercury reenters the evening sky low in the southwest in late October. Southern hemisphere observers are favored. Mercury is at the descending node on October 6th and reaches aphelion on October 16th.
At 40 degrees north latitude, Venus is just two degrees high 30 minutes after the Sun sets. Venus is stationary on October 5th and retrogrades sunward afterwards. The brightest planet passes six degrees south of the Sun when it achieves inferior conjunction on October 26th. Just prior to that Venus will appear as an extremely thin crescent and will subtend more one arc minute. Venus enters the morning sky in early November.
Mars fades from magnitude -1.3 to magnitude -0.6 and decreases in apparent size from 15.8 to 12.0 arc seconds this month. This is about half of its angular diameter when it achieved opposition in late July. Mars reaches culmination around 9:00 p.m. local daylight time at the start of the month. Mare Cimmerium is the most prominent albedo feature as October begins, followed by Mare Sirenum at the end of the first week. In mid-October, look for Solis Lacus (the Eye of Mars). Sinus Meridian and Sinus Sabaeus stand out a week later. During the final week of October, the bright Hellas basin and Syrtis Major make an appearance. The waxing gibbous Moon passes 1.9 degrees north of the Red Planet on October 18th. The eastward motion of Mars carries it from southwestern to northeastern Capricornus by the end of October. Martian surface feature simulators are available at https://is.gd/marsprofiler and https://www.calsky.com/cs.cgi/Planets/5/1
On October 1st, Jupiter is ten degrees above the horizon one hour after the Sun sets. It loses approximately three degrees of altitude each week. The waxing crescent Moon passes four degrees south of Mars on October 11th.
Saturn is low in the south in early evening in early October and sets around 11:00 p.m. local daylight time. By the end of the month, it sets after 9:00 p.m. Saturn lies 1.8 degrees south of the waxing crescent Moon on the evening of October 14th in the Americas. The Ringed Planet’s disk is some 16 arc seconds in angular diameter in mid-October. Its rings measure 37 arc seconds and are inclined 27 degrees. Twelfth-magnitude Enceladus reaches greatest eastern elongation on the night of October 1st. An illustration showing its position can be seen on page 42 of the October 2018 issue of Astronomy. For further information on Saturn’s satellites, browse http://www.skyandtelescope.com/observing/interactive-sky-watching-tools/
Uranus reaches opposition on October 24th. At that time, the seventh planet is located at a declination of +11.0 degrees (the highest it has been at opposition since February 1962), shines at magnitude +5.7, and subtends 3.7 arc seconds. The ice giant is located 2.8 degrees northeast of the fourth-magnitude star Omicron Piscium for several nights around the time of opposition. Browse http://www.bluewaterastronomy.info/resources/planets-charts-2018/09uranus_2018_1.pdf for a finder chart.
Neptune is located midway between the fourth-magnitude stars Lambda and Phi Aquarii in early October. The eighth planet’s retrograde (westward) motion takes it closer to Lambda over the course of the month. Its position is 2.1 degrees east of that star on October 31st. A finder chart is posted http://www.bluewaterastronomy.info/resources/planets-charts-2018/10neptune_2018_1.pdf
Additional online finder charts for Uranus and Neptune can be found at http://www.nakedeyeplanets.com/uranus.htm and http://www.nakedeyeplanets.com/neptune.htm and also at https://www.skyandtelescope.com/wp-content/uploads/WEB_UrNep18.pdf and on pages 48 and 49 of the September 2018 issue of Sky & Telescope.
The dwarf planet Pluto is located in northeastern Sagittarius near the Teaspoon asterism. Finder charts for Pluto are available on pages 48 and 49 of the July 2018 issue of Sky & Telescope and page 243 of the RASC Observer’s Handbook 2018. A finder chart is posted online at http://www.bluewaterastronomy.info/resources/planets-charts-2018/Pluto-mapFeb2018-Mar2019.jpg
For more on the planets and how to locate them, see http://www.nakedeyeplanets.com/
Comet 21P/Giacobini-Zinner should shine at eighth magnitude as it dives southeastward through Monoceros and Puppis this month. The periodic comet passes just north of the open cluster M50 on October 7th. Click on https://theskylive.com/21p-info and http://www.cometwatch.co.uk/comet-21p/ for additional information. Another periodic comet, Comet 38P/Stephan-Oterma, may shine at tenth magnitude as it heads northeastward through northeastern Orion and southwestern Gemini. It passes approximately five degrees north of the first-magnitude star Betelgeuse on the morning of October 1st and just over one degree south of the fourth-magnitude star Xi Orionis on the morning of October 8th. A finder chart appears on page 48 of the October 2018 issue of Sky & Telescope. Browse http://cometchasing.skyhound.com/ and http://www.aerith.net/comet/future-n.html for further information on comets visible this month. Other sources of information include https://theskylive.com/comets and http://www.shopplaza.nl/astro/comets/comets.htm and http://britastro.org/computing/charts_comet.html
Asteroid 4 Vesta shines at eighth magnitude as it travels eastward through Sagittarius this month. It lies 2.1 degrees to the west of Lambda Sagittarii (magnitude +2.8) on October 1st and within one degree of that star from October 5th to October 9th. Vesta passes 20 arc minutes south of Lambda Sagittarii on October 7th. It lies within one degree north of Sigma Sagittarii (magnitude +2.1) from October 21st to October 24th, passing just 40 arc minutes from that star on October 23rd. The second largest of the main belt asteroids glides south of three globular clusters during October. It lies within one degree of M28 and NGC 6638 during the first ten days of the month and within two degrees of M22 during the second week of October. Two asteroids brighter than magnitude +11.0 reach opposition this month, namely 63 Ausonia on October 7th and 346 Hermentaria on October 16th. The main belt asteroid 216 Kleopatra occults the star TYC 765-506-1 (magnitude +11.1) in northern Canis Major on the morning of October 28th. For information on this and other upcoming asteroid occultation events and on the bright asteroids, consult http://asteroidoccultation.com/ and http://www.curtrenz.com/asteroids.html respectively.
A wealth of current information on solar system celestial bodies is posted at http://nineplanets.org/ and http://www.curtrenz.com/astronomy.html
Various events taking place within our solar system are discussed at http://www.bluewaterastronomy.info/styled-4/index.html
Information on the celestial events transpiring each week can be found at http://astronomy.com/skythisweek and http://www.skyandtelescope.com/observing/sky-at-a-glance/
The famous eclipsing variable star Algol (Beta Persei) is at a minimum, decreasing in brightness from magnitude +2.1 to magnitude +3.4, on October 1st, 3rd, 6th, 9th, 12th, 15th, 18th, 21st, 23rd, 26th, and 29th. Consult page 49 of the October 2018 issue of Sky & Telescope for the minima times. On the night of October 20th, Algol shines at minimum brightness (magnitude +3.4) for approximately two hours on centered at 10:39 p.m. EDT (2:39 UT on October 21st). For more on Algol, see http://stars.astro.illinois.edu/sow/Algol.html and http://www.solstation.com/stars2/algol3.htm
Free star charts for the month can be downloaded at http://www.skymaps.com/downloads.html and https://www.telescope.com/content.jsp?pageName=Monthly-Star-Chart and http://whatsouttonight.com/
Data on current supernovae can be found at http://www.rochesterastronomy.org/snimages/
Finder charts for the Messier objects and other deep-sky objects are posted at https://freestarcharts.com/messier and https://freestarcharts.com/ngc-ic and http://www.cambridge.org/features/turnleft/seasonal_skies_july-september.htm
Telrad finder charts for the Messier Catalog and the SAC’s 110 Best of the NGC are posted at http://www.astro-tom.com/messier/messier_finder_charts/map1.pdf and http://sao64.free.fr/observations/catalogues/cataloguesac.pdf respectively.
Information pertaining to observing some of the more prominent Messier galaxies can be found at http://www.cloudynights.com/topic/358295-how-to-locate-some-of-the-major-messier-galaxies-and-helpful-advice-for-novice-amateur-astronomers/
Author Phil Harrington offers an excellent freeware planetarium program for binocular observers known as TUBA (Touring the Universe through Binoculars Atlas), which also includes information on purchasing binoculars, at http://www.philharrington.net/tuba.htm
Stellarium and Cartes du Ciel are useful freeware planetarium programs that are available at http://stellarium.org/ and https://www.ap-i.net/skychart/en/start
Deep-sky object list generators can be found at http://www.virtualcolony.com/sac/ and http://tonightssky.com/MainPage.php and https://dso-browser.com/
Freeware sky atlases can be downloaded at http://www.deepskywatch.com/files/deepsky-atlas/Deep-Sky-Hunter-atlas-full.pdf and http://astro.mxd120.com/free-star-atlases
Eighty-five binary and multiple stars for October: Struve 2973, Struve 2985, Struve 2992, Struve 3004, Struve 3028, Otto Struve 501, Struve 3034, Otto Struve 513, Struve 3050 (Andromeda); 29 Aquarii, 41 Aquarii, 51 Aquarii, 53 Aquarii, Zeta Aquarii, Struve 2913, Struve 2935, Tau-1 Aquarii, Struve 2944, Struve 2988, Psi-1 Aquarii, 94 Aquarii, 96 Aquarii, h3184, Omega-2 Aquarii, 107 Aquarii (Aquarius); Otto Struve 485, Struve 3037, 6 Cassiopeiae, Otto Struve 512, Sigma Cassiopeiae (Cassiopeia); Xi Cephei, Struve 2883, Struve 2893, Struve 2903, Krueger 60, Delta Cephei, Struve 2923, Otto Struve 482, Struve 2947, Struve 2948, Struve 2950, Struve 2984, Omicron Cephei, Otto Struve 502 (Cepheus); Otto Struve 459, h1735, Struve 2876, Otto Struve 465, Struve 2886, Struve 2894, h1756, Struve 2902, Struve 2906, 8 Lacertae, Otto Struve 475, 13 Lacertae, h1828, 16 Lacertae (Lacerta); Struve 2857, Struve 2877, 34 Pegasi, Struve 2908, Xi Pegasi, Struve 2958, Struve 2978, 57 Pegasi, Struve 2991, h1859, Struve 3007, Struve 3021, Otto Struve 504, Struve 3044 (Pegasus); Struve 3009, Struve 3019, Struve 3033 (Pisces); Eta Piscis Austrini, Beta Piscis Austrini, Dunlop 241, h5356, Gamma Piscis Austrini, Delta Piscis Austrini, h5371 (Piscis Austrinus); h5417, Delta Sculptoris, h5429 (Sculptor)
Notable carbon star for October: RZ Pegasi
Seventy-five deep-sky objects for October: NGC 7640, NGC 7662, NGC 7686 (Andromeda); NGC 7180, NGC 7183, NGC 7184, NGC 7293, NGC 7392, NGC 7585, NGC 7606, NGC 7721, NGC 7723, NGC 7727 (Aquarius); Cz43, K12, M52, NGC 7635, NGC 7788, NGC 7789, NGC 7790, St12 (Cassiopeia); B171, B173-4, IC 1454, IC 1470, K10, Mrk50, NGC 7235, NGC 7261, NGC 7354, NGC 7380, NGC 7419, NGC 7510 (Cepheus); IC 1434, IC 5217, NGC 7209, NGC 7223, NGC 7243, NGC 7245 (Lacerta); NGC 7177, NGC 7217, NGC 7320 (the brightest galaxy in Stephan’s Quintet), NGC 7331, NGC 7332, NGC 7339, NGC 7448, NGC 7454, NGC 7479, NGC 7619 (the brightest member of Pegasus I), NGC 7626, NGC 7678, NGC 7742, NGC 7769 (Pegasus); NGC 7541, NGC 7562, NGC 7611 (Pisces); IC 5156, IC 5269, IC 5271, NGC 7172, NGC 7173, NGC 7174, NGC 7176, NGC 7201, NGC 7203, NGC 7214, NGC 7221, NGC 7229, NGC 7314, NGC 7361 (Piscis Austrinus); NGC 7507, NGC 7513, NGC 7713, NGC 7755, NGC 7793 (Sculptor)
Top ten binocular deep-sky objects for October: M52, NGC 7209, NGC 7235, NGC 7243, NGC 7293, NGC 7510, NGC 7686, NGC 7789, NGC 7790, St12
Top ten deep-sky objects for October: K12, M52, NGC 7209, NGC 7293, NGC 7331, NGC 7332, NGC 7339, NGC 7640, NGC 7662, NGC 7789
Challenge deep-sky object for October: Jones 1 (PK104-29.1) (Pegasus)
The objects listed above are located between 22:00 and 24:00 hours of right ascension.