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 Mercury is in inferior conjunction with the Sun (0.563 astronomical units from the Earth; latitude -5.5 degrees) at 3:00
7/2 The Moon is 6.3 degrees north-northeast of the first-magnitude star Antares (Alpha Scorpii) at 2:00; asteroid 532 Herculina (magnitude +9.5) is at opposition in Sagittarius at 14:00
7/4 The Moon is at the descending node (longitude 269.1 degrees) at 3:00; Earth is at aphelion (152,095,295 kilometers or 94,507,635 miles from the Sun) at 12:00
7/5 A shallow penumbral eclipse of the Moon begins at 3:07; Full Moon, known as the Hay or Thunder Moon, occurs at 4:44; asteroid 4 Vesta is in conjunction with the Sun at 6:00; the Moon is 1.9 degrees southeast of Jupiter at 22:00
7/6 The Moon is 2.5 degrees south of Saturn at 10:00
7/8 Mars is at is at its greatest heliocentric latitude south at 1:00 (-1.8 degrees); Venus is at its brightest (magnitude -4.7) at 12:00
7/10 Venus is at greatest illuminated extent (47.4 square arc seconds) at 8:00; the Moon is 4.1 degrees southeast of Neptune at 12:00; Venus is at aphelion (0.7282 astronomical units) at 14:00
7/11 Mars passes north of the celestial equator at 12:00; the Moon is 1.8 degrees southeast of Mars at 22:00
7/12 Venus is 1.0 degree north of the first-magnitude star Aldebaran (Alpha Tauri) at 2:00; Mercury is stationary, with prograde or direct (eastward) motion to resume at 7:00; the Moon is at apogee, subtending 29' 34" from a distance of 404,199 kilometers (251,158 miles) at 19:27; Last Quarter Moon occurs at 23:29
7/13 Asteroid/dwarf planet 1 Ceres is stationary at 2:00; asteroid 2 Pallas (magnitude +9.6) is at opposition in Vulpecula at 2:00; Mercury is at its greatest heliocentric latitude south (-7.0 degrees) at 10:00
7/14 The Curtiss Cross, an X-shaped clair-obscure illumination effect located between the craters Parry and Gambart, is predicted to be visible at 1:55; Jupiter is at opposition (apparent size 47.6", magnitude -2.8) at 8:00; the Moon is 3.5 degrees southeast of Uranus at 15:00
7/15 Mercury (magnitude +1.6) is 6.0 degrees southeast of the bright open cluster M35 in Gemini at 3:00; Pluto is at opposition (apparent size 0.1", magnitude +14.3) at 12:00
7/16 The Moon is 6.6 degrees southeast of the bright open cluster M45 (the Pleiades or Subaru) in Taurus at 8:00
7/17 The Moon is 3.7 degrees north of Aldebaran at 1:00; the Moon, Venus, and Aldebaran lie within a circle with a diameter of 4.1 degrees at 2:00; the Moon is 3.1 degrees north of Venus at 7:00
7/18 The Moon is at the ascending node (longitude 89.0 degrees) at 13:00; the Moon is 0.6 degrees southeast of the bright open cluster M35 in Gemini at 19:00
7/19 The Moon is 3.9 degrees north of Mercury at 5:00
7/20 The Moon is 8.2 degrees south of the first-magnitude star Castor (Alpha Geminorum) at 6:00; the Moon is 4.5 degrees south of the first-magnitude star Pollux (Beta Geminorum) at 10:00; the Sun enters Cancer (ecliptic longitude 118.3 degrees) at 13:00; New Moon (lunation 1207) occurs at 17:33; Saturn is at opposition (apparent size 18.5", magnitude +0.1) at 22:00
7/21 The Moon is 2.0 degrees north-northeast of M44 (the Beehive Cluster or Praesepe) at 10:00
7/22 The Sun's ecliptic longitude is 120 degrees at 9:00; Mercury is at greatest western elongation (20.1degrees from Sun) at 15:00
7/23 The Moon is 4.1 degrees north-northeast of the first-magnitude star Regulus (Alpha Leonis) at 0:00
7/25 The Moon is at perigee, subtending 32' 26" at a distance of 368,361 kilometers (228,889 miles) at 5:02; 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 18:00
7/26 The Moon is 6.7 degrees north-northeast of the first-magnitude star Spica (Alpha Virginis) at 19:00
7/27 The First Quarter Moon occurs at 12:33; 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 be fully formed at 13:25
7/29 The peak of the Southern Delta Aquarid meteor shower (a zenithal hourly rate of 20 per hour) is predicted to occur at 22:00
7/30 The Moon is 6.2 degrees north-northeast of Antares at 3:00
7/31 The Moon is at the descending node (longitude 268.6 degrees) at 10:00
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. Hendri 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 29th 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/astronomy-essential ... eor-shower for further information. The Alpha Capricornids, the Piscis Austrinids, and the Northern Delta Aquarids are the other minor meteor showers with southern radiants occurring this month. A list of the year's meteor showers appears on page 254 of the RASC's Observer's Handbook 2020.
Information on passes of the ISS, the USAF’s X-37B, the HST, Starlink, and other satellites can be found at http://www.heavens-above.com/
The Moon is 9.6 days old, is illuminated 77.4%, subtends 32.6 arc minutes, and is located in Libra on July 1st at 0:00 UT. The Moon is at its greatest northern declination of +23.9 degrees on July 19th and its greatest southern declination of -24.1 degrees on July 5th. Longitudinal libration is at a maximum of +5.0 degrees on July 6th and a minimum of -5.4 degrees on July 19th. Latitudinal libration is at a maximum of +6.8 degrees on July 11th and a minimum of -6.7 degrees on July 25th. Favorable librations for the following lunar features occur on the indicated dates: Mare Australe on July 2nd, Mare Smythii on July 4th, Crater Mouchez on July 13th, and Crater Pascal on July 14th. New Moon takes place on July 20th. The Moon is at apogee (a distance of 63.37 Earth-radii) on July 12th and at perigee (a distance of 57.75 Earth-radii) on July 25th. A penumbral lunar eclipse visible from Antarctica, Africa, western Europe, North and South America, and the eastern Pacific Ocean takes place on July 5th. Greatest eclipse occurs at 4:30:02 UT1. Browse http://www.eclipsewise.com/oh/oh-figure ... -Fig04.pdf for more on the third lunar eclipse of 71 in Saros series 149 and the third of the year. Click on http://www.lunar-occultations.com/iota/iotandx.htm for information on lunar occultations taking place in July. Visit https://saberdoesthestars.wordpress.com ... the-stars/ for tips on spotting extreme crescent Moons and http://www.curtrenz.com/moon06.html for Full Moon data. Consult http://time.unitarium.com/moon/where.html or download http://www.ap-i.net/avl/en/start for current information on the Moon. See https://svs.gsfc.nasa.gov/4768 for a lunar phase and libration calculator and https://svs.gsfc.nasa.gov/4768 for the Lunar Reconnaissance Orbiter Camera (LROC) Quickmap. Click on https://www.calendar-12.com/moon_calendar/2020/july for a lunar phase calendar for this month. Times and dates for the lunar crater light rays predicted to occur this month are available at http://www.lunar-occultations.com/rlo/rays/rays.htm
The Sun is located in Gemini on July 1st. The Earth is farthest from the Sun, a distance of 1.0167 astronomical units, on July 4th. On that date, 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 (not visible, 12.0", 1% illuminated, 0.56 a.u., Gemini), Venus (-4.7 magnitude, 43.1", 19% illuminated, 0.39 a.u., Taurus), Mars (-0.5 magnitude, 11.4", 84% illuminated, 0.82 a.u., Pisces), Jupiter (-2.7 magnitude, 47.3", 100% illuminated, 4.17 a.u., Sagittarius), Saturn (+0.2 magnitude, 18.4", 100% illuminated, 9.05 a.u., Capricornus), Uranus (+5.8 magnitude, 3.5", 100% illuminated, 20.06 a.u. on July 16th, Aries), Neptune (+7.8 magnitude, 2.3", 100% illuminated, 29.36 a.u. on July 16th, Aquarius), and Pluto (+14.3 magnitude, 0.1", 100% illuminated, 33.08 a.u. on July 16th, Sagittarius).
Jupiter and Saturn are in the southeast during the evening. At midnight, Mars is in the east, Jupiter and Saturn are in the south, and Neptune is in the southeast. In the morning, Mercury can be found in the northeast, Venus and Uranus in the east, Mars and Neptune in the south, and Jupiter and Saturn in the southwest.
Jupiter, Saturn, Pluto, and asteroid 2 Pallas all achieve opposition this month. The Moon forms a compact equilateral triangle with Jupiter and Saturn on the night of July 5th. The Moon, Venus, and Aldebaran lie within a circle with a diameter of 4.1 degrees on July 17th. All seven major planets can be seen in the morning in late July.
Mercury is in inferior conjunction on July 1st and is at its most southerly latitude from the ecliptic plane on July 13th. Mercury reappears in the morning sky around July 17th. A waning crescent Moon passes four degrees north of the planet on the morning of July 19th. Greatest western elongation occurs on July 20th. On that date, Mercury shines at magnitude +0.3. It brightens to magnitude -0.1 by July 25 and magnitude -0.7 by July 31st.
Venus shrinks in apparent size from 43.1 to 27.5 arc seconds as it increases in illumination from 19 to 42%. During July, the planet's altitude at sunrise increases steeply from 21 to 35%. Venus travels through Melotte 25 (the Hyades) during the first part of the month. Venus is at greatest brilliancy on July 10th. It attains greatest illuminated extent and is also at aphelion on July 11th and passes one degree north of Aldebaran on the night of July 12th. A waning crescent Moon passes three degrees north of the brightest planet on the morning of July 17th. Venus lies 2.3 degrees southeast of the third-magnitude star Zeta Tauri by the end of the month.
Mars brightens from magnitude -0.5 to magnitude -1.1 and grows in apparent size from 11.4 to 14.5 arc seconds this month. The Red Planet rises around 11:15 p.m. local time by the end of July. It moves north of the celestial equator for the first time since last October on July 11th. The waning gibbous Moon passes two degrees south of the Mars on July 11th. Mars enters northwestern Cetus on July 8th but returns to Pisces near the end of the month.
During July, Jupiter travels four degrees to the west relative to the fixed stars of Sagittarius. The Full Moon passes less than two degrees to the south of the gas giant planet on the night of July 5th. Jupiter is at opposition on July 14th and is at its peak elevation of about 30 degrees for observers at 40 degrees north at local midnight. Jupiter subtends 47.6 arc seconds and shines brightly at magnitude -2.8 on that date. Information on Great Red Spot transit times and Galilean satellite events is available on pages 50 and 51 of the July 2020 issue of Sky & Telescope and online at http://www.skyandtelescope.com/observin ... ing-tools/ and https://www.projectpluto.com/jevent.htm
Saturn's disk subtends over 18 arc seconds and its rings, which are inclined almost 22 degrees, span 42 arc seconds. Saturn is located six degrees to the east of Jupiter on July 1st. On July 6th, a nearly Full Moon passes two degrees south of the Ringed Planet. Saturn is at opposition on July 20th. Eighth-magnitude Titan is due north of Saturn on July 15th and July 31st and due south of the planet on July 7th and July 23rd. The faint Saturnian satellite Iapetus is positioned one arc minute due north of Saturn on the nights of July 27th and July 28th. For further data on Saturn’s satellites, browse http://www.skyandtelescope.com/observin ... ing-tools/
Uranus can be found in southwestern Aries about half-way between the second-magnitude star Hamal (Alpha Arietis) and the third-magnitude star Menkar (Alpha Ceti). A waning crescent Moon passes less than four degrees southeast of Uranus on July 14th. Visit http://www.nakedeyeplanets.com/uranus.htm for a finder chart.
Neptune is located in eastern Aquarius about four degrees east-northeast of the fourth-magnitude star Phi Aquarii. A gibbous Moon passes four degrees southeast of Neptune on July 10th. The asteroid/dwarf planet 1 Ceres lies 13.5 degrees south of Neptune on July 1st. That distance increases to 16 degrees by the end of the month. Browse http://www.nakedeyeplanets.com/neptune.htm for a finder chart.
The dwarf planet Pluto is 41 arc minutes south of Jupiter on July 1st. It reaches opposition on July 15th. Finder charts can be found on pages 48 and 49 of the July 2020 issue of Sky & Telescope and on page 243 of the RASC Observer’s Handbook 2020.
For more on the planets and how to locate them, browse http://www.nakedeyeplanets.com/
Comet C/2017 T2 (PanSTARRS) heads southeastward through Canes Venatici and Coma Berenices this month. The fading comet passes less than two degrees to the west of Beta Comae Berenices on July 19th and less than five degrees to northeast of the globular clusters M53 and NGC 5053 on July 30th. The faint periodic comet 88P/Howell passes less than two degrees from Spica around the time of the New Moon. See http://cometchasing.skyhound.com/ and http://www.aerith.net/comet/future-n.html for additional information on comets visible this month.
Asteroid 56 Melete, which was at opposition on June 28th, travels southwestward through the region of Scutum, Serpens Cauda, and Ophiuchus. skimming through the dark nebulae LDN 453 and LDN 431. Asteroid 532 Herculina (magnitude +9.5) is at opposition on July 2, asteroid 2 Pallas (magnitude +9.6) is at opposition on July 13th, and asteroid 129 Antigone (magnitude +10.4) is at opposition on July 15th. On July 31st, 1 Ceres lies 0.8 degrees northwest of the third magnitude star 88 Aquarii. Information on asteroid occultations taking place this month is available at http://www.asteroidoccultation.com/2018_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
Information on the celestial events transpiring each week can be found at https://stardate.org/nightsky and http://astronomy.com/skythisweek and http://www.skyandtelescope.com/observin ... -a-glance/
Free star maps for July can be downloaded at http://www.skymaps.com/downloads.html and https://www.telescope.com/content.jsp?p ... Star-Chart
Data on current supernovae can be found at http://www.rochesterastronomy.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 https://www.cambridge.org/turnleft/seas ... -september
Telrad finder charts for the Messier Catalog and the SAC’s 110 Best of the NGC are posted at http://www.custerobservatory.org/docs/messier2.pdf and http://www.saguaroastro.org/content/db/ ... estNGC.pdf respectively.
Information pertaining to observing some of the more prominent Messier galaxies can be found at http://www.cloudynights.com/topic/35829 ... tronomers/
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.deepskywatch.com/files/deeps ... s-full.pdf and http://astro.mxd120.com/free-star-atlases
The multiple star 36 Ophiuchi consists of three orange dwarf stars. For more on this interesting system, see https://stardate.org/radio/program/orange-triplets and http://www.solstation.com/stars/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.
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