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July 2015 Celestial Calendar

Posted: Wed Jul 01, 2015 6:25 am
by Dave Mitsky
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 Venus is 0.4 degree south of Jupiter at 14:00
7/2 Full Moon, known as the Hay or Thunder Moon, occurs at 2:20
7/5 Venus is at the descending node today; the Moon is at perigee, subtending 32' 7" from a distance of 367,093 kilometers (228,101 miles), at 19:00
7/6 Neptune is 3 degrees south of the Moon at 8:00; Pluto (magnitude +14.1, apparent size 0.1") is at opposition at 16:00; the Earth is at aphelion (152,093,481 kilometers or 94,506,462 miles from the Sun) at 19:00
7/8 Last Quarter Moon occurs at 20:24
7/9 The Moon is 0.8 degree south of Uranus, with an occultation occurring in western Australia, far southern Madagascar, the Indian Ocean, and eastern Antarctica, at 3:00
7/10 Venus is at its greatest illuminated extent at 4:00; the Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to occur at 5:28
7/12 Mercury is at the ascending node today; the Moon is 0.9 degree north of the first-magnitude star Aldebaran (Alpha Tauri), with an occultation occurring in Iceland, Greenland, northern Canada, Alaska, eastern Russia, and northern Japan, at 18:00
7/16 Mercury is at perihelion today; New Moon (lunation 1145) occurs at 1:24
7/18 The Moon is 4 degrees south of Jupiter at 18:00
7/19 The Moon is 0.4 degree south of Venus, with an occultation occurring in French Polynesia, Melanesia, northeastern Australia, and New Guinea, at 1:00
7/21 The Moon is at apogee, subtending 29' 14" from a distance of 404,835 kilometers (251,553 miles), at 11:00
7/23 Venus is stationary at 6:00; 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 13:45; Mercury is in superior conjunction at 19:00
7/24 First Quarter Moon occurs at 4:04
7/25 Asteroid 1 Ceres (magnitude +7.8) is at opposition at 8:00
7/26 The Moon is 2 degrees north of Saturn at 8:00; Uranus is stationary at 16:00
7/27 Mercury is at its greatest heliocentric latitude north today
7/29 The Southern Delta Aquarid meteor shower (15 per hour) peaks at 15:00
7/31 Full Moon, a so-called Blue Moon, occurs at 10:43; Venus is 6 degrees south of Jupiter at 20:00

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.

Strong moonlight will interfere with the peak of this year’s Southern Delta Aquarid meteor shower on the morning of July 30th. The 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 USAF’s X-37B, the HST, and other satellites can be found at http://www.heavens-above.com/

The Moon is 14.4 days old and is located in Ophiuchus on July 1st at 0:00 UT. At that time, it is illuminated 98.5%. The Moon is at its greatest northern declination of +18.4 degrees on July 14th and its greatest southern declination of -18.4 degrees on July 1st and -18.3 degrees on July 28th. Longitudinal libration is at a maximum of +5.1 degrees on July 14th and a minimum of -6.6 degrees on July 27th. Latitudinal libration is at a maximum of +6.5 degrees on July 14th and a minimum of -6.5 degrees on July 1st and -6.6 degrees on July 28th. New Moon takes place on July 16th at 1:24 UT. Two Full Moons occur this month, the first so-called Blue Moon since August 2012. The Moon passes four degrees south of Jupiter on July 18th and two degrees north of Saturn on July 26th. During July, Venus, Uranus, and the first-magnitude star Aldebaran are occulted by the Moon from various parts of the world. See http://www.lunar-occultations.com/iota/iotandx.htm for information on these and other lunar occultations taking place this month. Visit http://saberdoesthestars.wordpress.com/ ... the-stars/ for tips on spotting extreme crescent Moons. Times and dates for the lunar light rays predicted to occur in July 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 on July 6th, when it is 3.3% more distant than it was at perihelion and 1.7% farther than its average distance.

Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on July 1st: Mercury (-0.2 magnitude, 7.0", 52% illuminated, 0.96 a.u., Taurus), Venus (-4.6 magnitude, 32.3", 34% illuminated, 0.52 a.u., Leo), Mars (+1.6 magnitude, 3.6", 100% illuminated, 2.58 a.u., Gemini), Jupiter (-1.8 magnitude, 32.4", 100% illuminated, 6.08 a.u., Leo), Saturn (+0.2 magnitude, 18.1", 100% illuminated, 9.18 a.u., Libra), Uranus (+5.8 magnitude, 3.5", 100% illuminated, 19.92 a.u. on July 16, Pisces), Neptune (+7.8 magnitude, 2.3", 100% illuminated, 29.25 a.u. on July 16, Aquarius), and Pluto (+14.1 magnitude, 0.1", 100% illuminated, 31.91 a.u. on July 16, Sagittarius).

Venus is located in the west, Jupiter in the west, and Saturn in the south during the evening. At midnight, Saturn is in the southwest and Neptune in the southeast. In the morning, Mercury can be found in the northeast, Uranus in the southeast, and Neptune in the south.

Mercury is at perihelion on July 16th. It reaches superior conjunction on July 23rd. By month’s end, Mercury shrinks to an angular diameter of 5.0 arc seconds but increases in illumination from 52 to 96% and brightens from magnitude -0.2 to magnitude -1.3.

Venus and Jupiter are in conjunction on July 1st. The two brightest planets are in conjunction again on July 31st. Venus and Jupiter are separated by less than seven degrees from July 1st to July 31st. The southwestern motion (as seen from mid-northern latitudes) of Venus increases the separation from 0.4 degree on July 1st to four degrees on July 9th. On July 10th, Venus shines at its brightest (magnitude -4.7) for the current apparition. Venus is situated three degrees from the first-magnitude star Regulus from July 11th to July 18th. The thin crescent Moon, Venus, Jupiter, and Regulus lie within seven degrees of one another on the evening of July 18th. Venus begins retrograde (westward) motion on July 23rd. During July, Venus increases in apparent diameter from 32.3 to 51.4 arc seconds and decreases in illumination from 34 to 8%.

Mars is not visible this month.

Jupiter lies low in the west in the constellation of Leo. Jupiter and Venus have the same apparent diameter (32 arc seconds) on July 1st. The two planets are positioned less than one degree apart that evening. The final of a series of mutual events of the Galilean satellites that began in August of last year take place for observers in western North America in early July. Ganymede partially occults Io for four minutes beginning at 10:29 p.m. CDT on July 2nd. On July 5th, Io occults Ganymede for two minutes starting at 10:18 p.m. MDT. Io occults Europa for five minutes starting at 9:46 p.m. MDT on July 7th.

In mid-July, Saturn’s rings span 40 arc seconds and are inclined by 24 degrees. The disk of the planet subtends 18 arc seconds at the equator. Saturn’s brightest satellite, eighth-magnitude Titan, passes due north of the planet on July 6th and July 22nd and due south on July 13th and July 29th. The much fainter satellite Iapetus lies 2.2 arc minutes south of the planet on July 16th. For further information on Saturn’s satellites, browse http://www.skyandtelescope.com/observin ... ing-tools/

Uranus remains within 0.6 degree of the fourth-magnitude star Zeta Piscium during July. It rises around midnight at the end of the month.

Neptune is 2.1 degrees southwest of the fourth-magnitude star Lambda Aquarii at the start of the month. By the end of July, the eighth planet is located 2.6 degrees from that star.

Finder charts for Uranus and Neptune can be found at http://www.nakedeyeplanets.com/uranus.htm and http://www.nakedeyeplanets.com/neptune.htm

Pluto reaches opposition on July 6th. A historic flyby by the New Horizons spacecraft takes place on July 14th. See pages 20 to 27 of the July issue of Sky & Telescope and https://www.nasa.gov/mission_pages/newh ... index.html for further information. Finder charts for Pluto are available on pages 52 and 53 of the July issue of Sky & Telescope and page 47 of the July issue of Astronomy and online at http://www.bluewaterastronomy.info/reso ... 2015_1.pdf

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

Comet 141P/Machholz travels from Pisces to Perseus this month, assuming that it is still intact. This periodic comet fragmented into five pieces a number of years ago and hasn’t been observed since 2005. Browse http://cometchasing.skyhound.com/ and http://www.aerith.net/comet/future-n.html for additional information on comets visible in July.

Asteroid/dwarf planet 1 Ceres (magnitude +7.8) reaches opposition in Sagittarius on July 25th. Asteroid 8 Leto reaches opposition (magnitude +10.2) in Microscopium on July 30th. Asteroid 2 Pallas dims from magnitude +9.5 to +9.8, as it heads southwestward through Hercules. Information on asteroid occultations taking place this month is available at http://www.asteroidoccultation.com/2015_07_si.htm

A wealth of current information on solar system celestial bodies is posted at http://www.curtrenz.com/astronomical.html and http://nineplanets.org/

Free star maps for July can be downloaded at http://www.skymaps.com/downloads.html and http://www.telescope.com/content.jsp?pa ... Star-Chart

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.