July Celestial Calendar by Dave Mitsky
All times, unless otherwise noted, are UT (subtract four hours and, when appropriate, one calendar day for EDT)
7/1 First Quarter Moon occurs at 0:51; Mercury (magnitude -1.1) is 8.2 degrees south of the first-magnitude star Castor (Alpha Geminorum) at 3:00; the Lunar X, also known as the Werner or Purbach Cross, an X-shaped illumination effect involving various rims and ridges between the craters La Caille, Blanchinus, and Purbach, is predicted to occur at 8:57; Jupiter is 2.6 degrees south-southwest of the Moon at 9:00
7/2 The Moon is 6.5 degrees north-northeast of the first-magnitude star Spica (Alpha Virginis) at 5:00; asteroid 3 Juno (magnitude +9.9) is at opposition at 13:00; the midpoint of the year occurs at 12:00
7/3 The Earth is at aphelion (152,092,504 kilometers or 94,505,901 miles from the Sun) at 20:00
7/5 Venus is at its greatest latitude south of the ecliptic plane (-3.4 degrees) at 4:00; Venus is 6.6 degrees south-southeast of the bright open cluster M45 (the Pleiades or Subaru) in Taurus at 8:00
7/6 Jupiter is at eastern quadrature (90 degrees from the Sun) at 3:00; the Moon is at apogee, subtending 29' 26" from a distance of 405,934 kilometers (252,236 miles) at 5:28
7/7 The Moon is 3.2 degrees north of Saturn at 4:00
7/9 Full Moon, known as the Hay or Thunder Moon, occurs at 4:07; Pluto (angular size 0.1", magnitude +14.2) is at opposition at 22:00
7/10 Mercury is 0.31degree north-northeast of the center of the bright open cluster M44 (the Beehive Cluster or Praesepe) in Cancer at 7:00
7/11 Jupiter (heliocentric longitude 205.4 degrees) and Uranus (heliocentric longitude 25.4 degrees) are at heliocentric opposition at 22:00
7/12 The Moon is at the descending node (longitude 324.5 degrees) at 5:18
7/13 The Moon is 0.83 degree south-southwest of Neptune, with an occultation occurring in Chatham Island, New Zealand, and most of Antarctica, at 18:00; Venus (magnitude -4.1) is 3.1 degrees north of the first-magnitude star Aldebaran (Alpha Tauri), at 23:00
7/16 Asteroid 1 Ceres (magnitude +8.9) is 0.36 degree south of the bright open cluster M35 in Gemini at 7:00; Last Quarter Moon occurs at 19:26
7/17 Uranus is 4.1 degrees north-northwest of the Moon at 2:00; the Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to be at a midpoint at 11:33
7/19 The Moon is 9.2 degrees south-southeast of M45 at 8:00; the Moon is 0.48 degree south of asteroid 8 Flora at 12:00
7/20 The Moon is 0.4 degree north of Aldebaran, with an occultation occurring in Hawaii, the Aleutian Islands, central and northeast Asia, and India, at 0:00; asteroid 8 Flora at perihelion (1.8557 astronomical units from the Sun) at 10:00; Venus is 2.7 degrees north of the Moon at 12:00; the Sun enters Cancer (ecliptic longitude 118.24 degrees) at 19:00
7/21 Uranus is at western quadrature at 0:00; the Moon is 5.0 degrees south of the bright open cluster M35 in Gemini at 12:00; the Moon is at perigee, subtending 33' 05" at a distance of 361,238 kilometers (224,462 miles) at 17:12
7/23 Mercury is at the descending node through the ecliptic plane at 4:00; New Moon (lunation 1170) occurs at 9:46; Mars is 3.1degrees north of the Moon at 12:00; the Moon is 2.8 degrees south of M44 at 21:00
7/25 The Moon is at the ascending node (longitude 144.3 degrees) at 0:47; the Moon is 0.84 degree north of Mercury, with an occultation occurring in northern Asia, most of Greenland, northern Europe, and the British Isles, at 9:00; the Moon is 0.07degree northwest of the first-magnitude star Regulus (Alpha Leonis), with an occultation occurring in Indonesia, Southern India, the Middle East, and northern Africa, at 11:00; Mercury (magnitude +0.3) is 0.95 degree south-southwest of Regulus (magnitude +1.4) at 22:00
7/26 The equation of time equals -6.54 minutes at 0:00
7/27 Mars is in conjunction with the Sun at 1:00
7/28 The Southern Delta Aquarid meteor shower (15 to 20 per hour) peaks at 3:00
7/29 The Moon is 6.6 degrees north-northeast of Spica at 12:00
7/30 Mercury is at greatest eastern elongation (27.2 degrees) at 5:00; First Quarter Moon occurs at 15:23
Friedrich Bessel was born this month.
The first photograph of a star, namely Vega, was taken on July 17, 1850. The first photograph of a total solar eclipse was taken on July 28, 1851.
Moonlight will not pose a problem for viewing the peak of this year’s Southern Delta Aquarid meteor shower on the morning of July 30th. The radiant is located northwest of the first-magnitude star Fomalhaut (Alpha Piscis Austrini). Southern hemisphere observers are favored. Click on http://earthsky.org/...#delta-aquarids for further information. Other minor meteor showers with southern radiants occurring this month are the Alpha Capricornids, the Piscis Austrinids, and the Northern Delta Aquarids.
Information on Iridium flares and passes of the ISS, the Tiangong-1, the Tiangong-2, the USAF’s X-37B, the HST, and other satellites can be found at http://www.heavens-above.com/
The Moon is 6.9 days old, is illuminated 50.1 %, subtends 30.8 arc minutes, and is located in Virgo on July 1st at 0:00 UT. The Moon is at its greatest northern declination of +19.4 degrees on July 22nd and its greatest southern declination of -19.3 degrees on July 8th. Longitudinal libration is at a maximum of +6.7 degrees on July 27th and a minimum of -6.6 degrees on July 15th. Latitudinal libration is at a maximum of +6.7 degrees on July 19th and a minimum of -6.7 degrees on July 5th. New Moon takes place on July 23rd. The Moon occults Mercury, Neptune, Aldebaran, and Regulus from various parts of the world this month. See http://www.lunar-occ...ota/iotandx.htm for information on these and other lunar occultations taking place in July. Visit http://saberdoesthes...does-the-stars/ for tips on spotting extreme crescent Moons. A favorable apparition of the Hesiodus lunar crater ray is predicted to occur at 00:11 UT on July 3rd. The times and dates for the other lunar crater light rays predicted to occur in July are available at http://www.lunar-occ...o/rays/rays.htm
The Sun is located in Gemini on July 1st. The Earth is farthest from the Sun on July 3rd, when it is 3.3% more distant than it was at perihelion and 1.7% farther than its average distance. The Sun enters Cancer on July 20th.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on July 1st: Mercury (-1.1 magnitude, 5.3", 95% illuminated, 1.28 a.u., Gemini), Venus (-4.2 magnitude, 18.2", 63% illuminated, 0.92 a.u., Taurus), Mars (+1.7 magnitude, 3.6", 100% illuminated, 2.62 a.u., Gemini), Jupiter (-2.1 magnitude, 37.4", 99% illuminated, 5.28 a.u., Virgo), Saturn (+0.1 magnitude, 18.3", 100% illuminated, 9.08 a.u., Ophiuchus), Uranus (+5.8 magnitude, 3.5", 100% illuminated, 19.98 a.u. on July 16, Pisces), Neptune (+7.8 magnitude, 2.3", 100% illuminated, 29.29 a.u. on July 16, Aquarius), and Pluto (+14.2 magnitude, 0.1", 100% illuminated, 32.36 a.u. on July 16, Sagittarius).
Mercury is located in the west, Jupiter in the southwest, Saturn in the south during the evening. At midnight, Jupiter is in the west, Saturn is in the south, and Neptune in the east. In the morning, Venus can be found in the east, Uranus in the southeast, and Neptune in the south.
Mercury undergoes a rather poor apparition for northern hemisphere observers this month. The speediest planet passes in front of M44 on July 10th and less than a degree south of the two-day-old Moon and Regulus on July 25th.
Venus rises about 3 hours before sunset by the end of July. As it heads eastward through Taurus, it passes seven degrees south of M45 on July 5th. By the end of the second week of the month, Venus glides by Aldebaran and the Hyades (Melotte 25). It lies three degrees north of the waning crescent Moon on July 20th. The brightest planet passes less than one degree south of the supernova remnant M1 (the Crab Nebula) on July 26th and 0.4 degree north of the third-magnitude star Zeta Tauri on July 27th.
Mars is in conjunction with the Sun in Cancer on July 27th.
Jupiter sets around 1:00 a.m. DST as the month begins. It decreases in brightness by a tenth of a magnitude and in apparent size by three arc seconds during July. Jupiter reaches eastern quadrature on July 6th. The Galilean satellite Callisto lies due north of the planet on the evening of July 15th. On the evening of July 18th, the four Galilean satellites are arranged in order of their orbital distance from Jupiter. The King of the Planets passes nine arc minutes west of the eleventh-magnitude spiral galaxy NGC 4941 in Virgo on July 31st. Information on Great Red Spot transit times and Galilean satellite events is available on page 51 of the July 2017 issue of Sky & Telescope and online at http://www.skyandtel...watching-tools/ and https://www.projectp....com/jevent.htm
In mid-July, Saturn’s rings span 41 arc seconds and are tilted 27 degrees with respect to the Earth. The disk of the planet subtends 18 arc seconds at the equator. On July 6th, an almost Full Moon passes three degrees north of the Ringed Planet. See http://www.skyandtel...lad-youre-back/ for a recent article on observing Saturn. Eighth-magnitude Titan passes due north of the planet on July 9th and July 25th and due south of it on July 1st and July 17th. The much fainter Saturnian satellite Iapetus shines at tenth magnitude and is positioned approximately nine arc minutes west of Saturn when it reaches greatest western elongation on July 25th. For further data on Saturn’s satellites, browse http://www.skyandtel...watching-tools/
Uranus can be found one degree north of the fourth-magnitude star Omicron Piscium this month. Visit http://bluewaterastr...-chart-2017.png and http://www.nakedeyep....com/uranus.htm for finder charts.
During July, Neptune continues to retrograde through Aquarius. The eighth planet is situated 0.2 degree southeast of the sixth-magnitude star 81 Aquarii at the start of the month. By the end of July, Neptune lies 0.3 degree southwest of that star. Browse http://bluewaterastr...-chart-2017.png and http://www.nakedeyep...com/neptune.htm for finder charts.
Finder charts for Uranus and Neptune can also be found at http://wwwcdn.skyand...s_Neptune17.pdf
Pluto reaches opposition in northern Sagittarius on July 9th. Articles on locating and observing Pluto are available on pages 48-50 of the July 2017 issue of Sky & Telescope and pages 56-59 of the July 2017 issue of Astronomy. A finder chart appears on page 243 of the RASC Observer’s Handbook 2017.
For more on the planets and how to locate them, browse http://www.nakedeyeplanets.com/
Comet C/2015 V2 (Johnson) heads southward through Virgo, Hydra, and Centaurus during July. It passes 0.3 degree south of the fourth-magnitude star Kappa Virginis on the evening of July 1st, two degrees west of the fourth-magnitude star Lambda Virginis on July 4th. In mid-July, Comet Johnson enters Hydra and glides three degrees east of the third-magnitude star Pi Hydrae on July 22nd. Browse http://cometchasing.skyhound.com/ and http://www.aerith.ne...t/future-n.html for additional information on comets visible this month.
During July, asteroid 6 Hebe heads southwestward through Ophiuchus. It passes through the northern portion of the globular cluster NGC 6366 on July 3rd. On July 4th, 6 Hebe lies approximately halfway between NGC 6366 and the star SAO 141665 (magnitude +4.5). Information on asteroid occultations taking place this month is available at http://www.asteroido.../2017_07_si.htm
Information pertaining to observing some of the more prominent Messier galaxies can be found at http://www.cloudynig...ur-astronomers/
Forty binary and multiple stars for July: Eta Draconis, 17 & 16 Draconis, Mu Draconis, Struve 2273, Nu-1 & Nu-2 Draconis, Psi Draconis (Draco); Kappa Herculis, Gamma Herculis, Struve 2063, 56 Herculis, Struve 2120, Alpha Herculis (Ras Algethi), Delta Herculis, Rho Herculis, Mu Herculis (Hercules); Rho Ophiuchi, Lambda Ophiuchi, 36 Ophiuchi, Omicron Ophiuchi, Burnham 126 (ADS 10405), Struve 2166, 53 Ophiuchi, 61 Ophiuchi (Ophiuchus); h5003 (Sagittarius); Xi Scorpii, Struve 1999, Beta Scorpii, Nu Scorpii, 12 Scorpii, Sigma Scorpii, Alpha Scorpii (Antares), h4926 (Scorpius); Struve 2007, 49 Serpentis, Struve 2031 (Serpens Caput); 53 Serpentis, Struve 2204, h4995, h2814 (Serpens Cauda); Epsilon Ursae Minoris (Ursa Minor)
Notable carbon star for July: T Draconis
Sixty-five deep-sky objects for July: NGC 6140, NGC 6236, NGC 6340, NGC 6395, NGC 6412, NGC 6503, NGC 6543 (Draco); IC 4593, M13, M92, NGC 6106, NGC 6166, NGC 6173, NGC 6181, NGC 6207, NGC 6210, NGC 6229, NGC 6482 (Hercules); B61, B62, B63, B64, B72, IC 4634, IC 4665, LDN 42, LDN 1773, M9, M10, M12, M14, M19, M62, M107, NGC 6284, NGC 6287, NGC 6293, NGC 6304, NGC 6309, NGC 6356, NGC 6366, NGC 6369, NGC 6384, NGC 6401, Tr 26 (Ophiuchus); NGC 6440, NGC 6445 (Sagittarius); B50, B55, B56, Cr 316, M4, M6, M7, M80, NGC 6144, NGC 6153, NGC 6192, NGC 6231, NGC 6242, NGC 6302, NGC 6337, NGC 6451 (Scorpius); NGC 6217, NGC 6324 (Ursa Minor)
Top ten binocular deep-sky objects for July: IC 4665, LDN 1773, M4, M6, M7, M10, M12, M13, M92, NGC 6231
Top ten deep-sky objects for July: M4, M6, M7, M10, M12, M13, M92, NGC 6210, NGC 6231, NGC 6543
Challenge deep-sky object for July: NGC 6380 (Scorpius)
The objects listed above are located between 16:00 and 18:00 hours of right ascension.