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 The Moon is 1.6 degrees south-southeast of Venus at 23:00
7/2 Asteroid 18 Melpomene (magnitude +9.2) is at opposition at 1:00; New Moon (lunation 1194) occurs at 19:16; a total solar eclipse visible from the southern Pacific Ocean, northern Chile, and central Argentina reaches greatest eclipse at 19:22:53
7/3 The Moon is at the ascending node (longitude 107.6 degrees) at 7:00; the Moon is 6.1 degrees south of the first magnitude star Pollux (Beta Geminorum) at 18:00
7/4 The Moon is 0.1 degree north of Mars, with an occultation occurring in Micronesia, most of Asia, the Arabian Peninsula, and the eastern tip of Africa, at 6:00; the Moon is 3.3 degrees north-northeast of Mercury at 10:00; the Moon lies within the bright open cluster M44 (the Beehive or Praesepe) in Cancer at 15:00; the Earth is at aphelion (152,104,285 kilometers or 94,513,221 miles from the Sun) at 22:00
7/5 The Moon is at perigee, subtending 32' 51" at a distance of 363,726 kilometers (226,009 miles) at 5:00; Venus is at the ascending node through the ecliptic plane at 13:00
7/6 The Moon is 3.1 degrees north-northeast of the first-magnitude star Regulus (Alpha Leonis) at 5:00
7/7 Mercury is stationary at 4:00; Venus is at its northernmost declination (23.4 degrees) at 5:00; Mercury is at aphelion at 7:00; Mercury (magnitude +2.0) is 4.0 degrees south of Mars (magnitude +1.8) at 14:00
7/9 First Quarter Moon occurs at 10:55; 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 begin at 15:58; Saturn (magnitude +0.1, apparent size 18.4") is at opposition at 17:00
7/10 The Moon is 7.3 degrees north-northeast of the first-magnitude star Spica (Alpha Virginis) at 0:00; the middle of the eclipse season (i.e., the Sun is at same ecliptic longitude as the Moon’s ascending node, 107.5 degrees) occurs at 0:00
7/13 The Moon is 7.8 degrees north-northeast of the first-magnitude star Antares (Alpha Scorpii) at 11:00; the Moon is 2.3 degrees north-northeast of Jupiter at 21:00
7/14 Pluto is at opposition (magnitude +14.2, apparent size 0.1") at 15:00
7/16 The Moon is 0.2 degree south of Saturn, with an occultation occurring in central South America, Easter Island, southern Polynesia, and eastern Melanesia, at 7:00; the Moon is at the descending node (longitude 287.7 degrees) at 9:00; the Moon is 0.04 degree south of Pluto, with an occultation occurring in western Micronesia, northern and central Australia, southern Indonesia, Madagascar, and eastern Africa, at 17:00; the Moon is at the descending node (longitude 287.7 degrees) at 9:00; a partial lunar eclipse visible from South America, Europe, Africa, most of Asia, and Australia reaches greatest eclipse at 21:30:44; Full Moon, known as the Hay or Thunder Moon, occurs at 21:38
7/18 Mars is at its greatest heliocentric latitude north today
7/19 The dwarf planet/asteroid 1 Ceres is stationary at 17:00
7/20 The Moon is at apogee, subtending 29' 28" from a distance of 405,481 kilometers (251,954 miles) at 23:59
7/21 The Sun enters Cancer, at longitude 118.3 degrees on the ecliptic, at 7:00; the Moon is 4.0 degrees south of Neptune at 8:00; Mercury reaches inferior conjunction at 12:00
7/22 Venus is 6.0 degrees south of Pollux at 17:00
7/23 The Sun’s ecliptic longitude is 120 degrees at 3:00
7/25 Last Quarter Moon occurs at 1:18; Mercury (magnitude +4.1) is 5.6 degrees south-southwest of Venus (magnitude -3.9) at 3:00; the Moon is 5.0 degrees south of Uranus at 7:00; the Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to be visible at 17:25
7/26 The equation of time, which yields the difference between mean solar time and apparent solar time, is at a minimum of -6.55 minutes, at 12:00
7/27 Mercury is at its greatest heliocentric latitude south today; the Moon is 7.9 degrees south-southeast of the bright open cluster M45 (the Pleiades or Subaru) in Taurus at 8:00
7/28 The Moon is 2.3 degrees north of the first-magnitude star Aldebaran (Alpha Tauri) at 1:00
7/30 The Southern Delta Aquarid meteor shower (15 to 20 per hour) peaks; the Moon is at the ascending node (longitude 107.6 degrees) at 17:00
7/31 The Moon is 4.5 degrees north of Mercury at 4:00; the Moon is 6.1 degrees south of Pollux at 4:00; Mercury is stationary at 19:00; the Moon is 0.7 degree northeast of Venus at 22:00
Friedrich Bessel (1784-1846) was born this month.
The light from Supernova SN 1054 was first noted by Chinese astronomers on July 4, 1054. The first lunar map was drawn by Thomas Harriot on July 26, 1609. Charles Messier discovered the globular cluster M28 in Sagittarius on July 27, 1764. Comet D/1770 L1 (Lexell) passed closer to the Earth than any comet in recorded history on July 1, 1770. Charles Messier discovered the globular cluster M54 in Sagittarius on July 24, 1778. Caroline Herschel discovered the open cluster NGC 6866 in Cygnus on July 23, 1783. The globular cluster NGC 6569 in Sagittarius was discovered by William Herschel on July 13, 1784. Karl Ludwig Hencke discovered asteroid 6 Hebe on July 1, 1847. 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. Henri-Alexandre Deslandres invented the spectroheliograph on July 24, 1853. Sinope, one of Jupiter’s many satellites was discovered by Seth Nicholson on July 21, 1914. Karl Jansky announced the detection of radio radiation from the center of the Milky Way on July 8, 1933. Seth Nicholson discovered Neptune’s satellite Lysithea on July 6, 1938. The Mariner 4 probe took the first close-up image of another planet, namely Mars, on July 14, 1965. The Apollo 11 lunar module landed on the Moon on July 20, 1969. Neptune’s satellites Despinea and Galatea are discovered using images from the Voyager 2 probe on July 27, 1989. Fragments of Comet D/1993 F2 (Shoemaker-Levy) impacted Jupiter on July 16, 1994. Prospero, one of the satellites of Uranus, is discovered by Matthew Holman on July 18, 1999. Pluto’s satellite Styx is discovered using images from the New Horizon probe on July 11, 2012.
The peak of the Southern Delta Aquarid meteor shower on the morning of July 30th is not compromised by moonlight. The radiant is located northwest of the first-magnitude star Fomalhaut (Alpha Piscis Austrini). Southern hemisphere observers are favored. Click on http://earthsky.org/...d-meteor-shower 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-2, the USAF’s X-37B, the HST, and other satellites can be found at http://www.heavens-above.com/
The Moon is 27.4 days old, is illuminated 5.0%, subtends 31.3 arc minutes, and is located in Taurus on July 1st at 0:00 UT. The Moon is at its greatest northern declination of +22.4 degrees on July 3rd and +22.3 on July 30th and its greatest southern declination of -22.4 degrees on July 16th. Longitudinal libration is at a maximum of +6.0 degrees on July 12th and a minimum of -6.9 degrees on July 27th. Latitudinal libration is at a maximum of +6.8 degrees on July 24th and a minimum of -6.8 degrees on July 9th. New Moon takes place on July 2nd. The Moon is at perigee on July 5th (distance 57.03 Earth-radii) and at apogee on July 27th (distance 63.58 Earth-radii). The Moon forms a triangle with Jupiter and Antares on the night of July 12th and lies almost halfway between Jupiter and Saturn on July 14th. A partial lunar eclipse, the 22nd of Saros 139, takes place on July 16th, with greatest eclipse occurring at 21:30:44 UT. Approximately 65% of the Moon will be covered by the Earth’s shadow. The eclipse is not visible from North America. The Moon occults Mars and Saturn from various parts of the world on July 4th and July 16th respectively. See http://www.lunar-occ...ota/iotandx.htm for information on lunar occultations taking place in July. Visit http://saberdoesthes...does-the-stars/ for tips on spotting extreme crescent Moons. Click on https://www.calendar...endar/2019/july for a lunar phase calendar for this month. The times and dates for the lunar crater light rays predicted to occur in July are available at http://www.lunar-occ.../rays/rays.htm
The Sun is located in Gemini on July 1st. The Earth is farthest from the Sun on July 4th, when it is 3.3% more distant than it was at perihelion and 1.7% farther than its average distance. A total solar eclipse visible from the southern Pacific Ocean, northern Chile, and central Argentina occurs on July 2nd. This will be the 58th eclipse of Saros 127. Greatest eclipse takes place in the southern Pacific Ocean at 19:22:53 UT and lasts for 4 minutes and 33 seconds. A partial solar eclipse can be seen from most of South America and a small portion of Central America. Consult https://eclipse.gsfc...E2019Jul02T.GIF for further information. The Sun enters Cancer on July 21st.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on July 1st: Mercury (+1.0 magnitude, 9.4", 27% illuminated, 0.72 a.u., Cancer), Venus (-3.9 magnitude, 9.9", 98% illuminated, 1.68 a.u., Taurus), Mars (+1.8 magnitude, 3.7", 99% illuminated, 2.56 a.u., Cancer), Jupiter (-2.6 magnitude, 45.5", 100% illuminated, 4.34 a.u., Ophiuchus), Saturn (+0.1 magnitude, 18.4", 100% illuminated, 9.05 a.u., Sagittarius), Uranus (+5.8 magnitude, 3.5", 100% illuminated, 20.05 a.u. on July 16th, Aries), Neptune (+7.8 magnitude, 2.3", 100% illuminated, 29.35 a.u. on July 16th, Aquarius), and Pluto (+14.2 magnitude, 0.1", 100% illuminated, 32.82 a.u. on July 16th, Sagittarius).
Mercury is located in the west, Mars in the northwest, Jupiter in the south, and Saturn in the southeast during the evening. At midnight, Jupiter is in the southwest, Saturn is in the south, and Neptune is in the east. In the morning, Venus can be found in the northeast, Saturn in the southwest, Uranus in the east, and Neptune in the south.
Mercury can be seen with difficulty low in west-northwest the evening sky in early July. A thin crescent Moon passes within three degrees of Mercury on July 4th. Mercury passes four degrees south of Mars on July 7th and less than six degrees south of Venus on July 25th. The speediest planet reaches inferior conjunction on July 21st.
Venus disappears into the glare of the Sun early in the month. It lies very low in the east-northeast at dawn on July 1st.
Mars is occulted by a thin crescent Moon from some parts of the world on July 4th. Mars is at its greatest heliocentric latitude north on July 18th. By the end of the month, Mars subtends just 3.5 arc seconds.
Jupiter drops in brightness by two tenths of a magnitude and in apparent size by more than two arc seconds this month. The gas giant subtends 44.4 arc seconds at its equator and 41.6 arc seconds at its poles at mid-month. It culminates shortly before 11:30 p.m. local time at the beginning of the month and just after 9:00 p.m. local time as July ends. The waxing gibbous Moon passes two degrees to the north of Jupiter on the night of July 13th. Favorable EDT transits by Io and its shadow take place on the nights of July 4th, July 11th, July 18th, and July 27th. Io reappears from eclipse approximately 14 arc seconds from the eastern limb at approximately 11:48 p.m. EDT on July 12th. Europa transits the planet at a favorable EDT time on July 23rd. EDT transits by Ganymede occur on July 24th and July 31st. Information on Great Red Spot transit times and Galilean satellite events is available on pages 50 and 51 of the July 2019 issue of Sky & Telescope and online at http://www.skyandtel...watching-tools/ and https://www.projectp....com/jevent.htm
When Saturn reaches opposition on July 9th, it is located to the east of the Teapot asterism in Sagittarius. At that time, the Ringed Planet shines at magnitude +0.1, subtends 18.4 arc seconds at its equator and 16.9 arc seconds at its poles, has a declination of -22 degrees, and is 75 light minutes from the Earth. Saturn’s rings span 41.8 arc seconds at opposition and are tilted greater than 24 degrees with respect to the Earth. The average number of days between successive oppositions is 378. Saturn passes 1.1 degrees south of the third-magnitude star Pi Sagittarii on July 20th and 0.7 degree southeast of the fourth-magnitude star Omicron Sagittarii on July 31st. The gas giant attains a maximum altitude of approximately 28 degrees during July. Saturn is occulted by a nearly Full Moon from some parts of the world on July 16th. The faint satellite Enceladus shines at twelfth magnitude and is 16 arc seconds to the east of the edge of Saturn’s A ring on July 9th. Iapetus shines at tenth magnitude and is positioned 8.4 arc minutes west of Saturn on the same night. Eight-magnitude Titan and tenth-magnitude Tethys are also west of the planet, while tenth-magnitude Rhea and Dione lie to the north. For further data on Saturn’s satellites, browse http://www.skyandtel...watching-tools/
Uranus can be found in southern Aries approximately ten degrees southeast of the second-magnitude star Hamal (Alpha Arietis) and 2.3 degrees south of the sixth-magnitude star 19 Arietis. A waning crescent Moon passes five degrees south of Uranus on July 25th. Visit http://www.bluewater...anus_2019_1.pdf and http://www.nakedeyep....com/uranus.htm for finder charts.
Neptune is located in eastern Aquarius. The eighth planet is situated just east of the fourth-magnitude star Phi Aquarii at the start of the month. By the end of July, Neptune lies 0.9 degree from that star. A waning gibbous Moon passes four degrees south of Neptune on July 21st. Browse http://www.bluewater...tune_2019_1.pdf and http://www.nakedeyep...com/neptune.htm for finder charts.
Finder charts for Uranus and Neptune are also available at https://www.skyandte...WEB_UrNep19.pdf
The dwarf planet Pluto is at opposition in eastern Sagittarius on July 14th. It’s occulted by a nearly Full Moon from some parts of the world on July 16th. Finder charts can be found at http://www.bluewater...9/Pluto2019.jpg and on page 48 and 49 of the July 2019 issue of Sky & Telescope and on page 243 of the RASC Observer’s Handbook 2019.
A podcast with information on the planets and other celestial bodies for this month can be heard at https://www.skyandte...cast-july-2019/
For more on the planets and how to locate them, browse http://www.nakedeyeplanets.com/
The periodic comet 168P/Hergenrother heads northeastward through the vicinity of Pisces, Cetus, and Aries during July. It may shine at only twelfth magnitude. See http://cometchasing.skyhound.com/ and http://www.aerith.ne...t/future-n.html for additional information on comets visible this month.
The dwarf planet/asteroid 1 Ceres shines at eighth magnitude as it journeys southwestward through Libra. It lies within three degrees of the second-magnitude binary star Beta Scorpii for the entire month. Asteroids brighter than magnitude +11.0 reaching opposition this month include 18 Melpomene (magnitude +9.2) in Scutum on July 2nd and 45 Eugenia (magnitude +10.8) in Capricornus on July 26th. Information on asteroid occultations taking place this month is available at http://www.asteroido.../2019_07_si.htm
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.bluewater...ed-4/index.html
Information on the celestial events transpiring each week can be found at http://astronomy.com/skythisweek and http://www.skyandtel...ky-at-a-glance/
Free star charts for the month can be downloaded at http://www.skymaps.com/downloads.html and https://www.telescop...thly-Star-Chart
Data on current supernovae can be found at http://www.rochester...y.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...y-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...charts/map1.pdf and http://www.saguaroas...k110BestNGC.pdf respectively.
Information pertaining to observing some of the more prominent Messier galaxies can be found at http://www.cloudynig...ur-astronomers/
Stellarium and Cartes du Ciel are two excellent 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.deepskywa...-atlas-full.pdf and http://astro.mxd120....ee-star-atlases
The multiple star 36 Ophiuchi consists of three orange dwarf stars. For more on this interesting system, see https://stardate.org...orange-triplets and http://www.solstatio...rs/36ophiu3.htm
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.