Post by Dave Mitsky on Oct 1, 2015 2:40:32 GMT
October Calendar by Dave Mitsky
All times, unless otherwise noted, are UT (subtract four hours and, when appropriate, one calendar day for EDT)
10/2 The Moon is 0.5 degree north of the first-magnitude star Aldebaran (Alpha Tauri), with an occultation taking place in North America, Japan, and Micronesia, at 13:00
10/3 Asteroid 15 Eunomia (magnitude +7.9) is at opposition at 11:00
10/4 Last Quarter Moon occurs at 21:06
10/6 The Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to occur at 15:59
10/8 Mercury is at the ascending node today; the peak of the Draconid meteor shower (10 to 30 per hour) occurs at 20:00; Venus is 0.7 degree north of the Moon, with an occultation taking place in Victoria Land, New Zealand, Melanesia, and Australia, at 21:00; Mercury is stationary at 22:00
10/9 Mars is 3 degrees north of the Moon at 17:00
10/10 Jupiter is 3 degrees north of the Moon at 0:00
10/11 Mercury is 0.9 degree north of the Moon, with an occultation taking place in parts of Antarctica, the Falkland Islands, and southern South America, at 12:00; the Moon is at apogee, subtending 29'40" from a distance of 406,388 kilometers (252,518 miles), at 13:00
10/12 Mercury is at perihelion today; Uranus (magnitude +5.7, apparent size 3.7") is at opposition at 4:00
10/13 Mars is at its greatest heliocentric latitude north today; the New Moon (lunation 1148) occurs at 0:06; asteroid 471 Papagena (magnitude +9.5) is at opposition at 7:00
10/16 Mercury is at greatest western elongation (18 degrees) at 3:00; Saturn is 3 degrees south of the Moon at 13:00
10/17 Mars is 0.4 degree north of Jupiter at 14:00
10/18 A double Galilean shadow transit (Ganymede and Io) begins at 10:42
10/20 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 occur at 3:24; First Quarter Moon occurs at 20:31
10/21 The peak of the Orionid meteor shower (15 per hour) occurs at 23:00
10/22 Mercury is at its greatest heliocentric latitude north today
10/23 Neptune is 3 degrees south of the Moon at 19:00
10/25 Asteroid 29 Amphitrite (magnitude +8.7) is at opposition at 12:00; a double Galilean shadow transit (Ganymede and Io) begins at 12:36
10/26 Venus is at the ascending node today; Venus is at greatest western elongation (46 degrees) at 7:00; Venus is 1.1 degrees south of Jupiter at 8:00; Uranus is 0.9 degree north of the Moon, with an occultation taking place in southern French Polynesia, New Zealand, and eastern Antarctica, at 10:00; the Moon is at perigee, subtending 33'03" from a distance of 358,464 kilometers (222,739 miles), at 13:00
10/27 Full Moon, known as the Blood Moon and this year’s Hunter’s Moon, occurs at 12:05
10/29 The Moon is 0.6 degree north of Aldebaran, with an occultation taking place in northern Asia, the northern Middle East, Russia, Europe, and northwestern Africa, at 23:00
Ejnar Hertzsprung and Henry Norris Russell were born this month.
The first recorded solar eclipse took place on October 22, 2136 B.C. Giovanni Cassini discovered Saturn’s odd satellite Iapetus on October 25, 1671. Two of the satellites of Uranus, Ariel and Umbriel, were discovered by William Lassell on October 24, 1851. Lassell discovered Triton, Neptune’s brightest satellite, on October 10, 1846. Edwin Hubble discovered Cepheid variable stars in M31 (the Andromeda Galaxy) on October 5, 1923.
The Draconid (formerly the Giacobinid) meteor shower peaks on the morning of October. 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. Consult pages 48 and 49 of the October issue of Sky & Telescope or earthsky.org/astronomy-essentials/everything-you-need-to-know-draconid-meteor-shower for additional information on the Draconid meteor shower. The Orionid meteor shower peaks on the night of October 21st. A waxing gibbous Moon will not adversely affect viewing the shower during the morning hours of October 22nd. Orionid meteors are fragments of Comet 1P/Halley. Browse www.timeanddate.com/astronomy/meteor-shower/orionid.html or 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-1, the USAF’s X-37B, the HST, and other satellites can be found at www.heavens-above.com/
During the final two weeks of the month, the zodiacal light may be visible in the pre-dawn eastern sky from a dark site. Articles on the zodiacal light appear at www.atoptics.co.uk/highsky/zod1.htm and oneminuteastronomer.com/6645/zodiacal-light/
The Moon is 17.7 days old, is illuminated 88.1%, and is located in Taurus on October 1st at 0:00 UT. Large tides occur on October 1st, 27th, 28th, 29th, and 30th. The Moon reaches its greatest northern declination on October 3rd (+18.1 degrees) and October 31st (+18.2 degrees) and its greatest southern declination on October 18th (-18.2 degrees). Longitudinal libration is at a maximum of +7.9 degrees on October 4th and a minimum of -6.9 degrees on October 19th. Latitudinal libration is at a maximum of +6.8 degrees on October 4th and +6.7 degrees on October 31st and a minimum of -6.8 degrees on October 18th. Visit saberdoesthestars.wordpress.com/2011/07/05/saber-does-the-stars/ for tips on spotting extreme crescent Moons and 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 www.lunar-occultations.com/rlo/rays/rays.htm
The Sun is located in Virgo on October 1st at 0:00 UT.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on October 1st: Mercury (not applicable, 10.2", 0%, 0.66 a.u., Virgo), Venus (-4.7, 33.0", 35%, 0.51 a.u., Leo), Mars (magnitude +1.8, 3.9", 97%, 2.39 a.u., Leo), Jupiter (magnitude -1.7, 31.4", 100%, 6.27 a.u., Leo), Saturn (magnitude +0.6, 15.7", 100%, 10.56 a.u., Libra), Uranus (magnitude +5.7, 3.7", 100%, 18.99 a.u. on October 16th, Pisces), Neptune (magnitude +7.8, 2.3", 100%, 29.25 a.u. on October 16th, Aquarius), and Pluto (magnitude +14.2, 0.1", 100%, 33.11 a.u. on October 16th, Sagittarius).
During October evenings, Saturn is in the southwest, Uranus is in the east, and Neptune is in the southeast. At midnight, Uranus is located in the south and Neptune in the southwest. Mercury, Venus, Mars, and Jupiter can be found in the east and Uranus in the west in the morning sky.
For observers at latitude 40 degrees north at midmonth, Mercury is visible during morning twilight, Venus rises at 3:00 a.m. local time, Mars rises at 4:00 a.m. local time, Jupiter rises at 4:00 a.m. local time, and Saturn sets at 8:00 p.m. local time.
Venus, Mars, and Jupiter reside in the constellation of Leo this month. The three planets form a compact triangle on the morning of October 28th. Venus, Mars, and Jupiter will fit into a circle with a diameter of 3.5 degrees on that date. The three planets constitute a trio, fitting into a five degree circle, from October 22nd to October 29th.
Mercury is readily visible in the morning sky in mid-October. The speediest planet is at the ascending node and is stationary on October 8th, reaches perihelion on October 12th, is at greatest western elongation on October 16th, and is at its greatest heliocentric latitude north on October 22nd. On October 11th, Mercury is less than one degree north of a thin crescent Moon. An occultation takes place in southern South America and parts of Antarctica. Mercury’s disk decreases from 10.2 to 5.2 arc seconds in apparent size but increases in illumination to 93% by end of the month.
Venus, Regulus, and a waning crescent Moon form a right triangle on the morning of October 8th. Venus is at the ascending node and is at greatest western elongation on October 26th. The brightest planet also passes within one degree of Jupiter on that date. Venus lies more than 25 degrees above the horizon at the onset of twilight on the morning of October 28th. During October, the apparent diameter of Venus drops from 33 to 23 arc seconds while it increases in phase from 34 to 53%.
Mars, Jupiter, and a waning crescent Moon form a triangle on the morning of October 9th. Mars is three degrees north of the Moon on that date. The Red Planet is at its greatest heliocentric latitude north on October 13th. Mars and Jupiter are in conjunction on the morning of October 17th. Mars (magnitude +1.7) and Jupiter (magnitude -1.8) are less than one half of a degree apart on that date.
Jupiter passes three degrees north of the waning crescent Moon on October 10th. Click on www.skyandtelescope.com/observing/interactive-sky-watching-tools/ to determine transit times of the central meridian by the Great Red Spot. Double Galilean shadow transits involving the shadows of Ganymede and Io take place on the mornings of October 18th and October 25th. Data on Galilean satellite events is available at www.skyandtelescope.com/observing/interactive-sky-watching-tools/ and on page 54 of the October issue of Sky & Telescope.
In early October, Saturn lies about 15 degrees above the horizon an hour after sunset. It is just five degrees in altitude by the end of the month. Saturn’s disk spans 16 arc seconds and its rings 36 arc seconds as the month begins. The ring tilt angle is 25 degrees. Saturn is 3 degrees south of the Moon on October 13th. On October 24th, Saturn passes 0.7 degree due north of the second-magnitude binary star Beta Scorpii. For information on Saturn’s major satellites, browse www.skyandtelescope.com/observing/interactive-sky-watching-tools/
Uranus reaches opposition on October 12th. At that time, the seventh planet shines at magnitude 5.7, subtends 3.7 arc seconds, and is 2.6 light-hours (1.8 billion miles) from the Earth. It is occulted by the Moon from some parts of the world on October 26th. Uranus is located two degrees east-southeast of the fourth-magnitude star Epsilon Piscium on October 1st and travels about one degree westward by month’s end.
On October 1st, Neptune lies less two degrees northeast of the fifth-magnitude star Sigma Aquarii and 0.9 degree due east of a seventh-magnitude star. As the month progresses, the planet heads west-southwestward and approaches even closer to that star.
Finder charts for Uranus and Neptune can be found on page 49 of the September issue of Sky & Telescope and online at www.nakedeyeplanets.com/uranus.htm and www.nakedeyeplanets.com/neptune.htm and at www.skyandtelescope.com/wp-content/uploads/WEB_UrNep_Finders.pdf
The dwarf planet Pluto is located in northern Sagittarius but is quite low in the sky as darkness falls. Finder charts for Pluto are available on pages 52 and 53 of the July issue of Sky & Telescope and page 47 of the July issue of Astronomy and online at www.skyandtelescope.com/wp-content/uploads/WEB_2015_Pluto.pdf and www.bluewaterastronomy.info/resources/MapsCharts/planets-2015/22pluto_2015_1.pdf
For more on the planets and how to locate them, see www.nakedeyeplanets.com/
During October, the periodic comet 67P/Churyumov-Gerasimenko glides southeastward through the head of Leo. It passes 16 arc minutes north of Eta Leonis (magnitude +3.5) on October 15th. For additional information on comets visible in October, browse cometchasing.skyhound.com/ and www.aerith.net/comet/future-n.html
Asteroid 4 Vesta dims from magnitude +6.2 to magnitude +6.8 as it travels southwestward through Cetus this month. It passes approximately two degrees south of Iota Ceti (magnitude +3.5) on October 21st. A finder chart appears on page 48 of the October issue of Sky & Telescope. The following asteroids brighter than magnitude +11.0 reach opposition this month: 74 Galatea (10/1, magnitude +10.6), 15 Eunomia (10/3, magnitude +7.9), 471 Papagena (10/13, magnitude +9.5), 356 Liguria (10/13, magnitude +10.8), 29 Amphitrite (10/25, magnitude +8.7), 14 Irene (10/29, magnitude +10.4), and 106 Dione (10/31, magnitude +10.8). The following asteroids will occult eighth-magnitude and ninth-magnitude stars from various parts of the United States this month: 675 Ludmilla on the morning of October 5th, 215 Oenone on the night of October 16-17th, and 415 Palatia on the evening of October 29th. Read more about these events on page 51 of the October issue of Sky & Telescope. For information on this year’s bright asteroids and upcoming asteroid occultation events respectively, consult www.curtrenz.com/asteroids.html and asteroidoccultation.com/
Free star maps for August can be downloaded at www.skymaps.com/downloads.html and www.telescope.com/content.jsp?pageName=Monthly-Star-Chart
The famous eclipsing variable star Algol (Beta Persei) is at a minimum, decreasing in magnitude from 2.1 to 3.4, on October 1st, 4th, 7th, 10th, 13th, 16th, 18th, 21st, 24th, 27th, and 30th. Consult www.skyandtelescope.com/observing/interactive-sky-watching-tools/ and page 51 of the October issue of Sky & Telescope for the times of the eclipses. For more on Algol, see stars.astro.illinois.edu/sow/Algol.html and www.solstation.com/stars2/algol3.htm
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.
All times, unless otherwise noted, are UT (subtract four hours and, when appropriate, one calendar day for EDT)
10/2 The Moon is 0.5 degree north of the first-magnitude star Aldebaran (Alpha Tauri), with an occultation taking place in North America, Japan, and Micronesia, at 13:00
10/3 Asteroid 15 Eunomia (magnitude +7.9) is at opposition at 11:00
10/4 Last Quarter Moon occurs at 21:06
10/6 The Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to occur at 15:59
10/8 Mercury is at the ascending node today; the peak of the Draconid meteor shower (10 to 30 per hour) occurs at 20:00; Venus is 0.7 degree north of the Moon, with an occultation taking place in Victoria Land, New Zealand, Melanesia, and Australia, at 21:00; Mercury is stationary at 22:00
10/9 Mars is 3 degrees north of the Moon at 17:00
10/10 Jupiter is 3 degrees north of the Moon at 0:00
10/11 Mercury is 0.9 degree north of the Moon, with an occultation taking place in parts of Antarctica, the Falkland Islands, and southern South America, at 12:00; the Moon is at apogee, subtending 29'40" from a distance of 406,388 kilometers (252,518 miles), at 13:00
10/12 Mercury is at perihelion today; Uranus (magnitude +5.7, apparent size 3.7") is at opposition at 4:00
10/13 Mars is at its greatest heliocentric latitude north today; the New Moon (lunation 1148) occurs at 0:06; asteroid 471 Papagena (magnitude +9.5) is at opposition at 7:00
10/16 Mercury is at greatest western elongation (18 degrees) at 3:00; Saturn is 3 degrees south of the Moon at 13:00
10/17 Mars is 0.4 degree north of Jupiter at 14:00
10/18 A double Galilean shadow transit (Ganymede and Io) begins at 10:42
10/20 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 occur at 3:24; First Quarter Moon occurs at 20:31
10/21 The peak of the Orionid meteor shower (15 per hour) occurs at 23:00
10/22 Mercury is at its greatest heliocentric latitude north today
10/23 Neptune is 3 degrees south of the Moon at 19:00
10/25 Asteroid 29 Amphitrite (magnitude +8.7) is at opposition at 12:00; a double Galilean shadow transit (Ganymede and Io) begins at 12:36
10/26 Venus is at the ascending node today; Venus is at greatest western elongation (46 degrees) at 7:00; Venus is 1.1 degrees south of Jupiter at 8:00; Uranus is 0.9 degree north of the Moon, with an occultation taking place in southern French Polynesia, New Zealand, and eastern Antarctica, at 10:00; the Moon is at perigee, subtending 33'03" from a distance of 358,464 kilometers (222,739 miles), at 13:00
10/27 Full Moon, known as the Blood Moon and this year’s Hunter’s Moon, occurs at 12:05
10/29 The Moon is 0.6 degree north of Aldebaran, with an occultation taking place in northern Asia, the northern Middle East, Russia, Europe, and northwestern Africa, at 23:00
Ejnar Hertzsprung and Henry Norris Russell were born this month.
The first recorded solar eclipse took place on October 22, 2136 B.C. Giovanni Cassini discovered Saturn’s odd satellite Iapetus on October 25, 1671. Two of the satellites of Uranus, Ariel and Umbriel, were discovered by William Lassell on October 24, 1851. Lassell discovered Triton, Neptune’s brightest satellite, on October 10, 1846. Edwin Hubble discovered Cepheid variable stars in M31 (the Andromeda Galaxy) on October 5, 1923.
The Draconid (formerly the Giacobinid) meteor shower peaks on the morning of October. 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. Consult pages 48 and 49 of the October issue of Sky & Telescope or earthsky.org/astronomy-essentials/everything-you-need-to-know-draconid-meteor-shower for additional information on the Draconid meteor shower. The Orionid meteor shower peaks on the night of October 21st. A waxing gibbous Moon will not adversely affect viewing the shower during the morning hours of October 22nd. Orionid meteors are fragments of Comet 1P/Halley. Browse www.timeanddate.com/astronomy/meteor-shower/orionid.html or 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-1, the USAF’s X-37B, the HST, and other satellites can be found at www.heavens-above.com/
During the final two weeks of the month, the zodiacal light may be visible in the pre-dawn eastern sky from a dark site. Articles on the zodiacal light appear at www.atoptics.co.uk/highsky/zod1.htm and oneminuteastronomer.com/6645/zodiacal-light/
The Moon is 17.7 days old, is illuminated 88.1%, and is located in Taurus on October 1st at 0:00 UT. Large tides occur on October 1st, 27th, 28th, 29th, and 30th. The Moon reaches its greatest northern declination on October 3rd (+18.1 degrees) and October 31st (+18.2 degrees) and its greatest southern declination on October 18th (-18.2 degrees). Longitudinal libration is at a maximum of +7.9 degrees on October 4th and a minimum of -6.9 degrees on October 19th. Latitudinal libration is at a maximum of +6.8 degrees on October 4th and +6.7 degrees on October 31st and a minimum of -6.8 degrees on October 18th. Visit saberdoesthestars.wordpress.com/2011/07/05/saber-does-the-stars/ for tips on spotting extreme crescent Moons and 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 www.lunar-occultations.com/rlo/rays/rays.htm
The Sun is located in Virgo on October 1st at 0:00 UT.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on October 1st: Mercury (not applicable, 10.2", 0%, 0.66 a.u., Virgo), Venus (-4.7, 33.0", 35%, 0.51 a.u., Leo), Mars (magnitude +1.8, 3.9", 97%, 2.39 a.u., Leo), Jupiter (magnitude -1.7, 31.4", 100%, 6.27 a.u., Leo), Saturn (magnitude +0.6, 15.7", 100%, 10.56 a.u., Libra), Uranus (magnitude +5.7, 3.7", 100%, 18.99 a.u. on October 16th, Pisces), Neptune (magnitude +7.8, 2.3", 100%, 29.25 a.u. on October 16th, Aquarius), and Pluto (magnitude +14.2, 0.1", 100%, 33.11 a.u. on October 16th, Sagittarius).
During October evenings, Saturn is in the southwest, Uranus is in the east, and Neptune is in the southeast. At midnight, Uranus is located in the south and Neptune in the southwest. Mercury, Venus, Mars, and Jupiter can be found in the east and Uranus in the west in the morning sky.
For observers at latitude 40 degrees north at midmonth, Mercury is visible during morning twilight, Venus rises at 3:00 a.m. local time, Mars rises at 4:00 a.m. local time, Jupiter rises at 4:00 a.m. local time, and Saturn sets at 8:00 p.m. local time.
Venus, Mars, and Jupiter reside in the constellation of Leo this month. The three planets form a compact triangle on the morning of October 28th. Venus, Mars, and Jupiter will fit into a circle with a diameter of 3.5 degrees on that date. The three planets constitute a trio, fitting into a five degree circle, from October 22nd to October 29th.
Mercury is readily visible in the morning sky in mid-October. The speediest planet is at the ascending node and is stationary on October 8th, reaches perihelion on October 12th, is at greatest western elongation on October 16th, and is at its greatest heliocentric latitude north on October 22nd. On October 11th, Mercury is less than one degree north of a thin crescent Moon. An occultation takes place in southern South America and parts of Antarctica. Mercury’s disk decreases from 10.2 to 5.2 arc seconds in apparent size but increases in illumination to 93% by end of the month.
Venus, Regulus, and a waning crescent Moon form a right triangle on the morning of October 8th. Venus is at the ascending node and is at greatest western elongation on October 26th. The brightest planet also passes within one degree of Jupiter on that date. Venus lies more than 25 degrees above the horizon at the onset of twilight on the morning of October 28th. During October, the apparent diameter of Venus drops from 33 to 23 arc seconds while it increases in phase from 34 to 53%.
Mars, Jupiter, and a waning crescent Moon form a triangle on the morning of October 9th. Mars is three degrees north of the Moon on that date. The Red Planet is at its greatest heliocentric latitude north on October 13th. Mars and Jupiter are in conjunction on the morning of October 17th. Mars (magnitude +1.7) and Jupiter (magnitude -1.8) are less than one half of a degree apart on that date.
Jupiter passes three degrees north of the waning crescent Moon on October 10th. Click on www.skyandtelescope.com/observing/interactive-sky-watching-tools/ to determine transit times of the central meridian by the Great Red Spot. Double Galilean shadow transits involving the shadows of Ganymede and Io take place on the mornings of October 18th and October 25th. Data on Galilean satellite events is available at www.skyandtelescope.com/observing/interactive-sky-watching-tools/ and on page 54 of the October issue of Sky & Telescope.
In early October, Saturn lies about 15 degrees above the horizon an hour after sunset. It is just five degrees in altitude by the end of the month. Saturn’s disk spans 16 arc seconds and its rings 36 arc seconds as the month begins. The ring tilt angle is 25 degrees. Saturn is 3 degrees south of the Moon on October 13th. On October 24th, Saturn passes 0.7 degree due north of the second-magnitude binary star Beta Scorpii. For information on Saturn’s major satellites, browse www.skyandtelescope.com/observing/interactive-sky-watching-tools/
Uranus reaches opposition on October 12th. At that time, the seventh planet shines at magnitude 5.7, subtends 3.7 arc seconds, and is 2.6 light-hours (1.8 billion miles) from the Earth. It is occulted by the Moon from some parts of the world on October 26th. Uranus is located two degrees east-southeast of the fourth-magnitude star Epsilon Piscium on October 1st and travels about one degree westward by month’s end.
On October 1st, Neptune lies less two degrees northeast of the fifth-magnitude star Sigma Aquarii and 0.9 degree due east of a seventh-magnitude star. As the month progresses, the planet heads west-southwestward and approaches even closer to that star.
Finder charts for Uranus and Neptune can be found on page 49 of the September issue of Sky & Telescope and online at www.nakedeyeplanets.com/uranus.htm and www.nakedeyeplanets.com/neptune.htm and at www.skyandtelescope.com/wp-content/uploads/WEB_UrNep_Finders.pdf
The dwarf planet Pluto is located in northern Sagittarius but is quite low in the sky as darkness falls. Finder charts for Pluto are available on pages 52 and 53 of the July issue of Sky & Telescope and page 47 of the July issue of Astronomy and online at www.skyandtelescope.com/wp-content/uploads/WEB_2015_Pluto.pdf and www.bluewaterastronomy.info/resources/MapsCharts/planets-2015/22pluto_2015_1.pdf
For more on the planets and how to locate them, see www.nakedeyeplanets.com/
During October, the periodic comet 67P/Churyumov-Gerasimenko glides southeastward through the head of Leo. It passes 16 arc minutes north of Eta Leonis (magnitude +3.5) on October 15th. For additional information on comets visible in October, browse cometchasing.skyhound.com/ and www.aerith.net/comet/future-n.html
Asteroid 4 Vesta dims from magnitude +6.2 to magnitude +6.8 as it travels southwestward through Cetus this month. It passes approximately two degrees south of Iota Ceti (magnitude +3.5) on October 21st. A finder chart appears on page 48 of the October issue of Sky & Telescope. The following asteroids brighter than magnitude +11.0 reach opposition this month: 74 Galatea (10/1, magnitude +10.6), 15 Eunomia (10/3, magnitude +7.9), 471 Papagena (10/13, magnitude +9.5), 356 Liguria (10/13, magnitude +10.8), 29 Amphitrite (10/25, magnitude +8.7), 14 Irene (10/29, magnitude +10.4), and 106 Dione (10/31, magnitude +10.8). The following asteroids will occult eighth-magnitude and ninth-magnitude stars from various parts of the United States this month: 675 Ludmilla on the morning of October 5th, 215 Oenone on the night of October 16-17th, and 415 Palatia on the evening of October 29th. Read more about these events on page 51 of the October issue of Sky & Telescope. For information on this year’s bright asteroids and upcoming asteroid occultation events respectively, consult www.curtrenz.com/asteroids.html and asteroidoccultation.com/
Free star maps for August can be downloaded at www.skymaps.com/downloads.html and www.telescope.com/content.jsp?pageName=Monthly-Star-Chart
The famous eclipsing variable star Algol (Beta Persei) is at a minimum, decreasing in magnitude from 2.1 to 3.4, on October 1st, 4th, 7th, 10th, 13th, 16th, 18th, 21st, 24th, 27th, and 30th. Consult www.skyandtelescope.com/observing/interactive-sky-watching-tools/ and page 51 of the October issue of Sky & Telescope for the times of the eclipses. For more on Algol, see stars.astro.illinois.edu/sow/Algol.html and www.solstation.com/stars2/algol3.htm
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.
