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October 2012 Celestial Calendar

Dave Mitsky

Note: All times in UTC (EST + 5)

Ejnar Hertzsprung and Henry Norris Russell were born this month.

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.

The Draconid (formerly the Giacobinid) meteor shower peaks on the evening of October 8. The Orionid meteor shower peaks during the morning of October 21. The waxing crescent Moon sets as Orion rises in the east so conditions will be excellent. Orionid meteors are fragments of Comet 1P/Halley. A Taurid fireball swarm is a possibility from October 28 to November 11. Unfortunately, the Moon is full on October 29.

During the second half of the month, the zodiacal light may be visible in the pre-dawn eastern sky from a dark site.

The Moon is 14.9 days old and is located in Pisces on October 1 at 0:00 UT. The Moon reaches its greatest northern declination on October 6 (+21.0 degrees) and its greatest southern declination on October 19 (-21.0 degrees). Longitudinal libration is at a maximum of +6.8 degrees on October 24 and a minimum of -6.7 degrees on October 11. Latitudinal libration is at a maximum of +6.8 degrees on October 11 and a minimum of -6.8 degrees on October 24. Large tides will occur from October 15 through October 18. 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 1 at 0:00 UT. The first recorded solar eclipse took place on October 22, 2136 B.C.

Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on October 1: Mercury (magnitude -0.4, 5.0", 91% illuminated, 1.35 a.u., Virgo), Venus (-4.1 magnitude, 15.8", 71% illuminated, 1.06 a.u., Leo), Mars (magnitude 1.2, 4.8", 93% illuminated, 1.94 a.u., Libra), Jupiter (magnitude -2.5, 43.1", 99% illuminated, 4.58 a.u., Taurus), Saturn (magnitude 0.7, 15.5", 100% illuminated, 10.69 a.u., Virgo), Uranus (magnitude 5.7, 3.7", 100% illuminated, 19.06 a.u., Pisces), Neptune (magnitude 7.9, 2.3", 100% illuminated, 29.19 a.u., Aquarius), and Pluto (magnitude 14.1, 0.1", 100% illuminated, 32.31 a.u., Sagittarius).

During October evenings, Mercury and Mars are in the southwest, Saturn is in the west, Uranus is in the east, and Neptune is in the southeast. At midnight, Jupiter is located in the east, Uranus in the south, and Neptune in the southwest. Venus can be found in the east and Jupiter is in the southwest in the morning sky.

At midmonth, Mercury can be seen during evening twilight, Venus rises at 4:00 a.m. local time, Mars sets at 8:00 p.m. local time, Jupiter rises at 9:00 p.m. local time and crosses the meridian at 4:00 a.m. local time, and Saturn sets at 7:00 p.m. local time for observers at latitude 40 degrees north.

The finest evening apparition of Mercury for southern hemisphere observers takes place this month. Mercury passes 1.8 degrees north of Spica on October 1, three degrees south of Saturn on October 6, and close to the Moon on the evening of October 16. The speediest planet is at aphelion on October 8 and greatest eastern elongation on October 26.

Venus passes a mere seven arc minutes south of Regulus on October 3, the closest approach of a planet to a first-magnitude star this year, and six degrees north of the waning crescent Moon on October 6. It is within 2.5 degrees of Regulus from October 1 to October 5 and five degrees of Regulus through October 7. As the month progresses, Venus climbs higher into the sky. Northern hemisphere observers have a more favorable view due to the angle of the ecliptic. By the end of October, Venus rises three hours before the Sun. The most brilliant planet drops slightly in magnitude (-4.1 to -4.0) and apparent size (16 to 13 arc seconds) but grows more gibbous (71 to 80% illuminated) during the course of the month.

Mars travels eastward from Libra into Scorpius on October 6 and into Ophiuchus after the middle of October. Observers in the southern hemisphere are favored. Mars passes between Delta and Beta Scorpii on the nights of October 11 and October 12. The Red Planet lies 3.5 degrees north of the slightly brighter Antares, the "rival of Ares", on October 20.

Jupiter commences retrograde (i.e., westward) motion towards Aldebaran on October 4. It's occulted by the Moon, an event not visible from our location, on the next day. Click on http://www.skyandtelescope.com/observing/objects/planets/3304091.html?page=1&c=y to determine transit times of the central meridian by the Great Red Spot. Data on the Galilean satellites is available at http://www.skyandtelescope.com/observing/objects/javascript/3307071.html

Saturn is in conjunction with the Sun on October 25.

Uranus spends October retrograding through Pisces. It culminates at midnight. Uranus is located 0.3 degree west-southwest of the sixth-magnitude star 44 Piscium on October 1. By the end of October, the westward motion of the planet increases the separation to 1.5 degrees.

As Neptune retrogrades through Aquarius this month, it is located less than 0.5 degree south of the fifth-magnitude star 38 Capricorni.

Finder charts for Uranus and Neptune can be found at http://media.skyandtelescope.com/documents/Uranus-Neptune-2012.pdf and page 50 of the September issue of Sky & Telescope.

Pluto is located in northern Sagittarius near the open cluster M25. The dwarf planet is visible shortly after nightfall. Detailed finder charts are available on pages 52 and 53 of the June issue of Sky & Telescope and on page 236 of the RASC Observer's Handbook 2012.

For more on the planets and how to locate them, browse http://www.nakedeyeplanets.com/

Asteroid 1 Ceres (magnitude 8.5) travels eastward through northeastern Orion and southwestern Gemini this month. It's occulted by the Moon on October 7 and is stationary on October 31. Asteroid 4 Vesta (magnitude 7.8) heads eastward through Taurus before retrograding. It is stationary on October 21. A finder chart for the two minor planets appears on page 51 of the October issue of Sky & Telescope. During October, asteroid 2 Pallas glides southwestward through western Cetus. Pallas (magnitude 8.3) lies about one degree south-southwest of Iota Ceti (magnitude 3.5) on October 1. The faint asteroids 371 Bohemia, 521 Brixia, and 35 Leukothea occult stars on the morning of October 13, late on the night of October 21, and the evening of October 31 respectively (see page 52 of the October issue of Sky & Telescope). For information on this year's bright asteroids and upcoming asteroid occultation events respectively, consult http://www.curtrenz.com/asteroids and http://asteroidoccultation.com/

Comet C/2011 F1 (LINEAR) takes a southeastern course through Serpens Caput this month. On October 1, the tenth-magnitude comet is 0.4 degree northeast of the fifth-magnitude star 3 Serpentis. Comet F1 LINEAR lies within two degrees of the bright globular cluster M5 (magnitude 5.7) from October 4 to October 8.

The famous eclipsing variable star Algol (Beta Persei) is at a minimum, decreasing in magnitude from 2.1 to 3.4, on October 1, 4, 7, 9, 12, 15, 18, 21, 24, 27, and 30. Consult http://www.skyandtelescope.com/observing/objects/variablestars/Minima_of_Algol.html for the times of the eclipses. For more on Algol, see http://stars.astro.illinois.edu/sow/Algol.html and http://www.solstation.com/stars2/algol3.htm

A free star map for October can be downloaded at http://www.skymaps.com/downloads.html

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

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.