August Celestial Calendar by Dave Mitsky
All times, unless otherwise noted, are UT (subtract four hours and, when appropriate, one calendar day for EDT)
8/1 The astronomical cross-quarter day known as Lammas or Lughnassad occurs today
8/2 Venus is at the ascending node today
8/3 The Lunar X, also known as the Werner or Purbach Cross, an X-shaped clair-obscur illumination effect involving various ridges and crater rims located between the craters La Caille, Blanchinus, and Purbach, is predicted to occur at 4:14; Mars is 2 degrees south of the Moon at 10:00
8/4 First Quarter Moon occurs at 0:50; Saturn is 0.1 degree north of the Moon, with an occultation occurring in Samoa, Fiji, Australia, Indonesia, and southern India, at 11:00
8/7 Asteroid 16 Psyche (magnitude +9.3) is at opposition at 3:00; the exact center of astronomical summer occurs at 6:40; Venus is 7 degrees south of the first-magnitude star Pollux (Beta Geminorum) at 21:00
8/8 Mercury is in superior conjunction at 16:00
8/9 Mercury is at its greatest heliocentric latitude north today
8/10 Full Moon (known as the Fruit, Grain, Green Corn, or Sturgeon Moon), the largest of the year, occurs at 18:09; the Moon is at perigee, subtending nearly 33'29'' from a distance of 356,896 kilometers (221,765 miles), at 18:00
8/12 Neptune is 5 degrees north of the Moon at 2:00
8/13 The peak of the Perseid meteor shower (a zenithal hourly rate of 60 to 100 per hour) occurs at 0:00
8/14 Uranus is 1.2 degrees south of the Moon, with an occultation occurring in the Arctic and central Asia, at 17:00
8/17 Last Quarter Moon occurs at 12:26
8/18 Venus is 0.2 degree north of Jupiter at 2:00; Venus is south of the bright open cluster M44 (the Beehive or Praesepe) at 13:00; the Moon is 1.6 degrees north of the first-magnitude star Aldebaran (Alpha Tauri) at 18:00
8/19 The Curtiss Cross, an X-shaped clair-obscur illumination effect located between the craters Parry and Gambart, is predicted to occur at 7:06
8/23 Jupiter is 5 degrees north of the Moon at 17:00
8/24 The Moon is at apogee, subtending 29'23'' from a distance of 406,523 kilometers (252,601 miles), at 0:00
8/25 New Moon (lunation 1134) occurs at 14:13
8/27 Mercury is 3 degrees north of the Moon at 6:00; Mars is 4 degrees south of Saturn at 13:00
8/29 Neptune (magnitude +7.8, apparent size 2.3") is at opposition at 15:00
8/31 Saturn is 0.4 degree south of the Moon, with an occultation occurring in central west Africa, northeastern South America, the Caribbean, Mexico, and the eastern United States, at 19:00
John Flamsteed and Maria Mitchell were born this month. The gibbous phase of Mars was first observed by Francesco Fontana on August 24, 1738. William Herschel discovered Enceladus on August 28, 1789. Asaph Hall discovered Deimos on August 11, 1877 and Phobos on August 17, 1877.
The peak of the Perseid meteor shower is adversely affected by moonlight from a waning gibbous Moon this year. Comet 109P/Swift-Tuttle is the source of Perseid meteors. For more on this year’s Perseids, click on http://www.timeandda...er/perseid.html and http://earthsky.org/...d-meteor-shower
The Moon is 5.1 days old and located in Virgo on August 1 at 0:00 UT. The Moon is at its greatest northern declination on August 19th (+18.8 degrees) and its greatest southern declination on August 7th (-8.8 degrees). Longitudinal libration is at a maximum of +7.7 degrees on August 16th and -7.8 degrees on August 4th. Latitudinal libration is at a maximum of +6.7 degrees on August 22nd and a minimum of -6.6 degrees on August 9th. The largest Full Moon of 2014, a so-called Super Moon, occurs on August 10th. Large tides will take place on August 10th through August 13th. The Moon is at perigee on August 10th and apogee on August 24th. It is 1.6 degrees north of the first-magnitude star Aldebaran on August 18th. The Moon occults Saturn from certain parts of the world on August 4th and again on August 31st. The Moon forms a compact triangle with Venus and Jupiter on the morning of August 23rd and with Mars and Saturn on the evening of August 31st. Browse http://www.curtrenz.com/occultations and http://www.lunar-occ...bstar/bstar.htm for information on lunar occultations. Visit http://saberdoesthes...does-the-stars/ for tips on spotting extreme crescent Moons. Times and dates for the lunar light rays predicted to occur in August are available at http://www.lunar-occ...o/rays/rays.htm
The Sun is located in Cancer on August 1st.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on August 1: Mercury (magnitude -1.5, 5.3", 93% illuminated, 1.27 a.u., Cancer), Venus (magnitude -3.8, 10.8", 92% illuminated, 1.55 a.u., Gemini), Mars (magnitude +0.4, 7.9", 87% illuminated, 1.19 a.u., Virgo), Jupiter (magnitude -1.8, 31.4", 100% illuminated, 6.28 a.u., Cancer), Saturn (magnitude +0.5, 17.1", 100% illuminated, 9.73 a.u., Libra), Uranus (magnitude +5.8, 3.6", 100% illuminated, 19.40 a.u. on August 16th, Pisces), Neptune (magnitude +7.8, 2.4", 100% illuminated, 28.99 a.u. on August 16th, Aquarius), and Pluto (magnitude +14.1, 0.1", 100% illuminated, 31.95 a.u. on August 16th, Sagittarius).
This month Mercury is visible in the west, Mars and Saturn in the southwest, and Neptune in the east during the evening. At midnight, Uranus can be found in the east and Neptune in the southeast. In the morning, Venus and Jupiter are in the east, Uranus is in the south, and Neptune is in the southwest.
Two notable planetary conjunctions take place during August: Venus and Jupiter in the morning sky at midmonth and Mars and Saturn in the evening sky near the end of the month.
Mercury is at superior conjunction on August 8th. It appears again near the end of the month in the evening sky. Mercury is three degrees north of the waxing crescent Moon on August 27th.
Venus spans some 10 arc minutes and is almost fully illuminated throughout the month. Venus exits Gemini and enters Cancer on its way to a close conjunction with Jupiter. Venus (magnitude -3.8) and Jupiter (magnitude -1.8) lie within four degrees of each other from August 14th through August 21st. They are separated by just 12 arc minutes at 4:00 UT on August 18th, the closest approach of the two planets in 14 years. On that date, Venus lies one degree south of the bright open cluster M44 at 13:00 UT. Venus crosses into Leo on August 26th.
On the morning of August 3rd, the waxing crescent Moon passes two degrees south of Mars. Mars departs Virgo and enters Libra on August 9th. Mars and Saturn grow closer together during the course of the month. The two planets lie within four degrees of one another by August 20th and will remain so until August 29th. Both planets shine at magnitude +0.6 during that period. The third-magnitude multiple star Zubenelgenubi (Alpha Librae) lies 1.5 degrees from Mars on August 21st. On August 27th, Mars passes 3.6 degrees south of Saturn. The waxing crescent Moon joins the trio of Mars, Saturn, and Zubenelgenubi on August 31st.
Jupiter reappears low in the east-northeastern morning sky a week after August begins. By August 18th, the gas giant joins Venus in the best close conjunction of the two bright planets since May 17, 2000. Like Venus, Jupiter changes little in brightness and apparent size during the course of the month.
Saturn is 17 arc seconds in angular size during August. Its rings are inclined by 21 degrees and span 38 arc seconds. The Moon occults Saturn from the eastern United States on the afternoon of August 31st. For information on Saturn’s satellites, browse http://www.skyandtel...watching-tools/
Uranus rises approximately 90 minutes after Neptune and can be found 2.2 degrees south-southwest of the fourth-magnitude star Epsilon Piscium in southern Pisces at the start of August. By the end of the month, the planet is located 0.4 degree farther away from the star.
As the month begins, Neptune is located 1.4 degrees northeast of the fifth-magnitude star Sigma Aquarii. The eighth planet’s retrograde motion carries it approximately 0.7 degree from the star by August 31st. Neptune (magnitude +7.8) reaches opposition on August 29th. At that time, the eighth planet is positioned 10 degrees south of the celestial equator and is some 29.0 astronomical units or four light-hours distant from the Earth.
Finder charts for Uranus and Neptune can be found at http://d366w3m5tf081...eptune_2014.pdf
The dwarf planet Pluto lies in northern Sagittarius. A finder chart is available on pages 50 and 51 of the June issue of Sky & Telescope and at http://www.bluewater...2014_2_810K.jpg
For more on the planets and how to locate them, see http://www.nakedeyeplanets.com/
Browse http://cometchasing....ets/2014_E2.pdf for a finder chart and http://www.livecomet...014-e2-jacques/ for data on the morning comet C/2014 E2 (Jacques). For further information on comets visible in August, browse http://cometchasing.skyhound.com/ and http://www.aerith.ne...t/future-n.html
Asteroids 1 Ceres and 4 Vesta remain within five degrees of one another as they depart Virgo and enter Libra this month. The two brightest asteroids shine at ninth and eighth magnitude respectively as they pass north of the fourth-magnitude star Kappa Virginis. A finder chart can be found on page 43 of the August issue of Astronomy. Asteroid 16 Psyche (magnitude +9.3) is at opposition in Capricornus at 3:00 UT on August 7th. An occultation of the tenth-magnitude star HIP 76622 in Libra by the faint asteroid 232 Russia (magnitude +14.8) is visible, along a narrow track running from North Dakota to southern New Jersey, at approximately 1:47 UT on August 20th UT. For more on this occultation and on other asteroid occultations taking place this month, see http://www.asteroido.../2014_08_si.htm
Sixty binary and multiple stars for August: 5 Aquilae, Struve 2404, 11 Aquilae, Struve 2426, 15 Aquilae, Struve 2449, 23 Aquilae, Struve 2532, Pi Aquilae, 57 Aquilae (Aquila); Beta Cygni (Albireo), 16 Cygni, Delta Cygni, 17 Cygni (Cygnus); 41 & 40 Draconis, 39 Draconis, Struve 2348, Sigma Draconis, Struve 2573, Epsilon Draconis (Draco); 95 Herculis, 100 Herculis, Struve 2289, Struve 2411 (Hercules); Struve 2349, Struve 2372, Epsilon-1 & Epsilon-2 Lyrae (the Double-Double), Zeta-2 Lyrae, Beta Lyrae, Otto Struve 525, Struve 2470 & Struve 2474 (the Other Double-Double) (Lyra); 67 Ophiuchi, 69 Ophiuchi, 70 Ophiuchi, Struve 2276, 74 Ophiuchi (Ophiuchus); Mu Sagittarii, Eta Sagittarii, 21 Sagittarii, Zeta Sagittarii, H N 119, 52 Sagittarii, 54 Sagittarii (Sagittarius); Struve 2306, Delta Scuti, Struve 2373 (Scutum); Struve 2296, Struve 2303, 59 Serpentis, Theta Serpentis (Serpens Cauda); Struve 2445, Struve 2455, Struve 2457, 4 Vupeculae, Struve 2521, Struve 2523, Struve 2540, Struve 2586, Otto Struve 388, Struve 2599 (Vulpecula)
Notable carbon star for August: V Aquilae
Eighty deep-sky objects for August: B139, B142, B143, NGC 6709, NGC 6738, NGC 6741, NGC 6751, NGC 6755, NGC 6772, NGC 6778, NGC 6781, NGC 6804, PK64+5.1 (Aquila); NGC 6819, NGC 6826, NGC 6834, (Cygnus); NGC 6643, NGC 6742 (Draco); DoDz 9 (Hercules); M56, M57, NGC 6703, NGC 6791, Ste1 (Lyra); NGC 6572, NGC 6633 (Ophiuchus); H20, M71 (Sagitta); B86, B87, B90, B92, B93, M8, M17, M18, M20, M21, M22, M23, M24, M25, M28, M54, M55, M69, M70, M75, NGC 6520, NGC 6544, NGC 6546, NGC 6553, NGC 6565, NGC 6603, NGC 6818, NGC 6822 (Sagittarius); IC 4703, IC 4756, M16, NGC 6604 (Serpens Cauda); B100, B101, B103, B104, B110, B111, B113, Bas 1, IC 1295, M11, M26, NGC 6649, NGC 6712 (Scutum); Cr 399 (asterism), M27, NGC 6802, NGC 6823, NGC 6834, NGC 6940, St 1 (Vulpecula)
Top ten binocular deep-sky objects for August: Cr 399, IC 4756, M8, M11, M17, M22, M24, M25, M27, NGC 6633 (IC 4756 and NGC 6633 are collectively known as the Binocular Double Cluster)
Top ten deep-sky objects for August: M8, M11, M16, M17, M20, M22, M24, M27, M55, M57
Challenge deep-sky object for August: Abell 53 (Aquila)
The objects listed above are located between 18:00 and 20:00 hours of right ascension.