May Sky Notes
May Celestial Calendar by Dave Mitsky
All times, unless otherwise noted, are UT (subtract four hours and, when appropriate, one calendar day for EDT)
5/2 Saturn (magnitude +0.5) is 2.7 degrees west of Pluto (magnitude +14.3) at 5:00; the Moon is 4.0 degrees north of Venus at 12:00; the Moon is 0.2 degree north of asteroid 4 Vesta, with an occultation occurring in southern Europe, northwestern Africa, the Cape Verde Islands, the Azores, northern South America, and the Galapagos Islands, at 13:00; the Moon is 3..4 degrees south-southeast of Venus at 15:00
5/3 The Moon is 2.7 degrees south-southeast of Mercury at 10:00; Mars and Saturn are at heliocentric opposition (longitudes 105.2 degrees and 285.2 degrees) at 14:00
5/4 The Moon is 4.4 degrees south-southeast of Uranus at 3:00; New Moon (lunation 1192) occurs at 22:46
5/5 Today is May Day or Beltane, a cross-quarter day; the peak of the Eta Aquarid meteor shower (20 per hour for northern hemisphere observers) occurs at 13:00
5/6 The Moon is 7.9 degrees south-southeast of the bright open cluster M45 (the Pleiades or Subaru) in Taurus at 5:00; the Moon is 2.2 degrees north of the first-magnitude star Aldebaran (Alpha Tauri) at 22:00
5/8 The Moon is 3.2 degrees south-southeast of Mars at 1:00; Mercury (magnitude -0.8) is 1.3 degrees south-southeast of Uranus (magnitude +5.9) at 16:00
5/9 The Moon is at descending node (longitude 109.3 degrees) at 19:00
5/10 The Moon is 6.3 degrees south of the first-magnitude star Pollux (Beta Geminorum) at 3:00; Venus is at its southernmost latitude from the ecliptic plane (-3.4 degrees) at 6:00
5/11 The Moon lies within the bright open cluster M44 (the Beehive Cluster or Praesepe) in Cancer at 2:00; the Lunar X (also known as the Werner or Purbach Cross), an X-shaped clair-obscure illumination effect involving various rims and ridges between the craters La Caille, Blanchinus, and Purbach, is predicted to be fully formed at 16:25; asteroid 8 Flora (magnitude +9.8) is at opposition at 23:00
5/12 First Quarter Moon occurs at 1:12; the Moon is 2.9 degrees north-northeast of the first-magnitude star Regulus (Alpha Leonis) at 17:00
5/13 The Moon is at perigee, subtending 32' 23'' from a distance of 369,009 kilometers (229,291 miles), at 21:53
5/14 The equation of time is at a maximum of 3.65 minutes at 9:00; asteroid 11 Parthenope (magnitude +9.5) is at opposition at 10:00; the Sun enters Taurus (longitude 53.47 degrees on the ecliptic) at 13:00
5/16 The Moon is 7.1 degrees north-northeast of the first-magnitude star Spica (Alpha Virginis) at 12:00; Mars is at its northernmost declination (24..6 degrees) at 22:00
5/18 Venus (magnitude -3.9) is 1.1 degrees south-southeast of Uranus (magnitude +5.9) at 17:00; Full Moon, known as the Milk or Planting Moon, occurs at 21:11
5/19 Mercury is at the ascending node through the ecliptic plane at 15:00; Mars is 0.2 degree north of the bright open cluster M35 in Gemini at 16:00; the Moon is 1.2 degrees south of the dwarf planet/asteroid 1 Ceres, with an occultation occurring in parts of Antarctica, at 18:00; the Moon is 7.8 degrees north-northeast of the first-magnitude star Antares (Alpha Scorpii) at 21:00
5/20 Asteroid 20 Massalia (magnitude +9.8) is at opposition at 13:00; the Moon is 1.7 degrees north-northeast of Jupiter at 18:00
5/21 The Sun’s longitude is 60 degrees at 8:00; Mercury is in superior conjunction (a distance of 1.322 a.u. from Earth and a latitude of 1.42 degrees) with the Sun at 13:00; Mercury is 3.7 degrees south-southeast of M45 at 15:00
5/22 The Moon is at the descending node (longitude 288.5 degrees) at 19:00; the Moon, Saturn, and Pluto lie within a circle with a diameter of 2.94 degrees at 23:00; the Moon is 0.5 degree south of Saturn, with an occultation occurring in southern New Zealand, most of Australia, the Kerguelen Islands, parts of eastern Antarctica, and the southern tip of Africa, at 22:00
5/23 The Moon is 0.1 degree south of Pluto, with an occultation occurring in southern and eastern Africa and central South America, at 4:00
5/24 Mercury is at perihelion (0.3075 a.u. from the Sun) at 7:00
5/25 Mercury is 6.5 degrees north-northwest of Aldebaran at 18:00
5/26 The Moon is at apogee, subtending 29' 34'' from a distance of 404,137 kilometers (251,119 miles), at 13:27; Last Quarter Moon occurs at 16:34
5/27 The Curtiss Cross, an X-shaped clair-obscure illumination effect located between the craters Parry and Gambart, is predicted to be visible at 19:32; the Moon is 3.5 degrees south-southeast of Neptune at 20:00
5/28 The dwarf planet/asteroid 1 Ceres (magnitude +7.0) is at opposition at 23:00
5/30 The Moon is 0.6 degree north of asteroid 4 Vesta, with an occultation occurring in northwestern North America, the Aleutian Islands, northwestern Micronesia, eastern Asia, and parts of Indonesia, at 22:00
5/31 The Moon is 4.5 degrees south-southeast of Uranus at 14:00
Nicolas Lacaille (1713-1762), Otto Wilhelm Struve (1819-1905), Joseph Lockyer (1836-1920), Williamina Fleming (1857-1911), and Frank Drake (1930) were born this month.
The first recorded perihelion passage of Comet Halley (1P/Halley) occurred on May 25, 240 BC. Thales of Miletus accurately predicted a solar eclipse on May 28, 585 BC. The German astronomers Gottfried and Maria Magarethe Kirch discovered the bright globular cluster M5 on May 5, 1702. On May 1, 1759, the English amateur astronomers John Bevis and Nicholas Munckley observed Comet Halley on its first predicted return. The French astronomer Charles Messier discovered the globular cluster M3 on May 3, 1764 and the globular cluster M10 on May 29, 1764. The Italian astronomer Annibale de Gasparis discovered asteroid 11 Parthenope on May 11, 1850. Asteroid 14 Irene was discovered on May 19, 1851 by the English astronomer John Russell Hind. The German astronomer Robert Luther discovered asteroid 26 Proserpina on May 6, 1853. The Australian astronomer John Tebbutt discovered the Great Comet of 1861 (C/1861 J1 and 1861 II) on May 13, 1861. The English astronomer Norman Pogson discovered asteroid 80 Sappho on May 2, 1864. Norman Pogson discovered asteroid 87 Sylvia on May 16, 1866. The 40-inch Clark refractor at the Yerkes Observatory saw first light on May 21, 1897. The Griffith Observatory opened to the public on May 14, 1935. Nereid, Neptune’s third-largest satellite, was discovered on May 1, 1949 by the Dutch-American astronomer Gerard Kuiper.
The broad peak of the Eta Aquarid meteor shower is not adversely affected by moonlight this year. Southern hemisphere observers are favored. Eta Aquarid meteors are debris from the famous periodic comet 1P/Halley. The radiant is located close to the Water Jug asterism in Aquarius. See https://www.amsmeteors.org/meteor-showers/meteor-shower-calendar/#eta+Aquariids https://www.amsmeteors.org/meteor-showers/meteor-shower-calendar/#eta+Aquariids and page 48 of the May 2019 issue of Sky & Telescope http://www.imo.net/2018-eta-aquariids-predictions-and-observations/for additional information on the Eta Aquarids.
Information on the few remaining Iridium satellite 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/ http://www.heavens-above.com/
The Moon is 25.5 days old, is illuminated 16.2%, subtends 29.3 arc minutes, and is located in Aquarius on May 1st at 0:00 UT. The Moon is at its greatest northern declination on May 9th (+22.2 degrees). The Moon is at its greatest its greatest southern declination on May 22nd (-22.3 degrees). Longitudinal libration is at maximum (+5.0 degrees) on May 19th and at minimum (-5.0 degrees) on May 6th. Latitudinal libration is at maximum (+6.6 degrees) on May 3rd and again (+6.7 degrees) on May 30th and at minimum (-6.6 degrees) on May 16th. The Moon is at apogee (distance 63.36 Earth-radii) on May 26th and at perigee (distance 57.86 Earth-radii) on May 13th. New Moon occurs on May 4th. The 39%-illuminated Moon transits M44 from 2:00 to 4:00 UT on May 11th. See https://occultations.org/campaigns/ https://occultations.org/campaigns/ for further information on this event. The Moon occults 4 Vesta on May 2nd and May 30th, 1 Ceres on May 19th, Saturn on May 22nd, and Pluto on May 23rd from certain parts of the world. Consult http://www.lunar-occultations.com/iota/iotandx.htm http://www.lunar-occultations.com/iota/iotandx.htm for more on lunar occultations. Visit http://saberdoesthestars.wordpress.com/2011/07/05/saber-does-the-stars/ http://saberdoesthestars.wordpress.com/2011/07/05/saber-does-the-stars/ for tips on spotting extreme crescent Moons. Click on http://www.calendar-12.com/moon_calendar/2019/may http://www.calendar-12.com/moon_calendar/2019/may for a lunar phase calendar. Times and dates for the lunar light rays predicted to occur this month are available at http://www.lunar-occultations.com/rlo/rays/rays.htm http://www.lunar-occultations.com/rlo/rays/rays.htm
The Sun is located in Aries on May 1st. It enters Taurus on May 14th.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on May 1st: Mercury (magnitude -0.4, 5.8", 75% illuminated, 1.15 a.u., Pisces), Venus (magnitude -3.8, 11.5", 88% illuminated, 1.45 a.u., Pisces), Mars (magnitude +1.6, 4.2", 96% illuminated, 2.24 a.u., Taurus), Jupiter (magnitude -2.5, 43.5", 100% illuminated, 4.54 a.u., Ophiuchus), Saturn (magnitude +0.5, 17.2", 100% illuminated, 9.67 a.u., Sagittarius), Uranus on May 16th (magnitude +5.9, 3.4", 100% illuminated, 20.79 a.u., Aires), Neptune on May 16th (magnitude +7.9, 2.3", 100% illuminated, 30.33 a.u., Aquarius), and Pluto on May 16th (magnitude +14.2, 0.1", 100% illuminated, 32.72 a.u., Sagittarius).
In the evening, Mercury is in the northwest and Mars is in the west. Jupiter is located in the southeast at midnight. Mercury, Venus, and Uranus can be seen in the east, Saturn in the south, Jupiter in the southwest, and Neptune in the southeast at dawn.
Mercury can be seen extremely low in the east during early part of the month. A very slender waning crescent Moon passes three degrees to the south of Mercury on May 3rd. Mercury is in superior conjunction on May 21st. As May ends, the speediest planet enters the evening sky and can be seen to the lower right of Mars in the west-northwest 30 minutes after the Sun sets. Mercury shines brightly at magnitude -1.2 at that time.
During May, Venus rises about an hour before the Sun and shines at its minimum brightness of magnitude -3.8. A thin waning crescent Moon passes four degrees south of the planet on May 2nd. Venus is at its greatest heliocentric latitude south on May 10th. Venus lies 1.2 degrees south of Uranus on May 18th.
Mars lies between the horns of Taurus, Beta and Zeta Tauri, on May 6th. A waxing crescent Moon passes three degrees south of the Red Planet on May 7th. Mars shrinks to 3.9 arc seconds and shines at only magnitude +1.8 by the end of May. Mars departs Taurus and enters Gemini by the middle of the month.
Jupiter increases in apparent size from 43.5 to 45.8 arc seconds this month. The waning gibbous Moon passes less than two degrees to the north of Jupiter on May 20th. The orbital plane of the Galilean satellites is currently inclined three degrees to our line of sight. A shadow transit by Ganymede begins at 3:42 a.m. EDT on the morning of May 7th. On the morning of May 18th, Ganymede reappears from occultation at 2:16 a.m. EDT. Io’s shadow begins to transit the planet at 3:44 a.m. EDT followed by Io itself at 4:17 a.m. EDT. Ganymede begins to disappear into eclipse to the west of Jupiter at 1:41 a.m. EDT on the morning of May 25th, an event that will take 14 minutes to transpire. Articles on observing Jupiter and the Great Red Spot (GRS) appear on pages 52 and 53 respectively of the May 2019 issue of Sky & Telescope. Browse http://www.skyandtelescope.com/observing/interactive-sky-watching-tools/ http://www.skyandtelescope.com/observing/interactive-sky-watching-tools/ or http://www.projectpluto.com/jeve_grs.htm http://www.projectpluto.com/jeve_grs.htm in order to determine transit times of Jupiter’s central meridian by the GRS. GRS transit information also appears on pages 50 and 51 of the May 2019 issue of Sky & Telescope. Data on the Galilean satellite events is available on page 51 of the May 2019 issue of Sky & Telescope and online at http://www.skyandtelescope.com/observing/interactive-sky-watching-tools/ http://www.skyandtelescope.com/observing/interactive-sky-watching-tools/ and http://www.projectpluto.com/jevent.htm http://www.projectpluto.com/jevent.htm
Saturn retrogrades through eastern Sagittarius this month. It shines at magnitude +0.4 and has an apparent equatorial diameter of almost 18 arc seconds at mid-month. Saturn’s rings subtend more than 40 arc seconds and are inclined by nearly 24 degrees at that time. In late May, Saturn nears the meridian as morning twilight begins. The waning gibbous Moon passes one half degree south of Saturn on May 22nd. Eighth-magnitude Titan, Saturn’s brightest satellite, is located south of the planet on May 4th and May 20th and north of it on May 12th and May 28th. Saturn’s odd satellite Iapetus shines faintly at eleventh magnitude when it passes north of Saturn on May 18th and May 19th. For further information on Saturn’s satellites, browse http://www.skyandtelescope.com/observing/interactive-sky-watching-tools/ http://www.skyandtelescope.com/observing/interactive-sky-watching-tools/
Uranus can be seen once again during morning twilight during the second half of May. Venus passes 1.2 degrees due south of Uranus on May 18th. On May 31st, the waning crescent Moon passes 4.5 degrees south-southeast of Uranus. The two celestial objects rise more than an hour before the Sun on that date.
Neptune is located 1.2 degrees east-northeast of the fourth-magnitude star Phi Aquarii in eastern Aquarius this month. The waning crescent Moon passes 3.5 degrees south-southeast of Neptune on May 27th. Neptune reaches an altitude of nearly 20 degrees in east-southeast as morning twilight begins on the final day of the month.
Pluto lies in northeastern Sagittarius and transits the meridian before dawn.
Comet C/2017 M4 (ATLAS) passes west-southwestward through Scorpius and into Lupus in May. This faint comet is located five degrees west of the third-magnitude star Mu1 Scorpii on May 1st. It passes a bit more than one degree north of the ninth-magnitude globular cluster NGC 6139 on May 3rd and 1.3 degrees south of the third-magnitude star Eta Lupi on May 13th. Visit http://cometchasing.skyhound.com/ http://cometchasing.skyhound.com/ and http://www.aerith.net/comet/weekly/current.html http://www.aerith.net/comet/weekly/current.html for information on comets visible this month.
The dwarf planet/asteroid 1 Ceres (magnitude +7.0) reaches opposition in western Ophiuchus on May 28th. Ceres retrogrades into Scorpius shortly thereafter. A finder chart can be found on page 48 of the May 2019 issue of Sky & Telescope. With a diameter of 940 kilometers (585 miles), Ceres is the largest object in the main asteroid belt and is the only asteroid to be differentiated, i.e., to have layers. Other asteroids brighter than magnitude +11.0 that reach opposition this month include 8 Flora (magnitude +9.8) on May 12th, 11 Parthenope (magnitude +9.5) on May 14th, 68 Leto (magnitude +10.7) on May 14th, 20 Massalia (magnitude +9.8) on May 20th, and 32 Pomona (magnitude +10.5) on May 27th. Information on asteroid occultations taking place this month is available at http://www.asteroidoccultation.com/2019_05_si.htm http://www.asteroidoccultation.com/2019_05_si.htm
For more on the planets and how to locate them, browse http://www.nakedeyeplanets.com/ http://www.nakedeyeplanets.com/
A wealth of current information on solar system celestial bodies is posted at http://www.curtrenz.com/astronomy.html http://www.curtrenz.com/astronomy.html and http://nineplanets.org/ http://nineplanets.org/
Various events taking place within our solar system are discussed at http://www.bluewaterastronomy.info/styled-4/index.html http://www.bluewaterastronomy.info/styled-4/index.html
Information on the celestial events transpiring each week can be found at http://astronomy.com/skythisweek http://astronomy.com/skythisweek and http://www.skyandtelescope.com/observing/sky-at-a-glance/ http://www.skyandtelescope.com/observing/sky-at-a-glance/
Free star maps for May can be downloaded at http://www.skymaps.com/downloads.html http://www.skymaps.com/downloads.html and https://www.telescope.com/content.jsp?pageName=Monthly-Star-Chart https://www.telescope.com/content.jsp?pageName=Monthly-Star-Chart
Data on current supernovae can be found at http://www.rochesterastronomy.org/snimages/ http://www.rochesterastronomy.org/snimages/
Finder charts for the Messier objects and other deep-sky objects are posted at https://freestarcharts.com/messier https://freestarcharts.com/messier and https://freestarcharts.com/ngc-ic https://freestarcharts.com/ngc-ic and http://www.cambridge.org/features/turnleft/seasonal_skies_april-june.htm http://www.cambridge.org/features/turnleft/seasonal_skies_april-june.htm
Telrad finder charts for the Messier Catalog and the SAC’s 110 Best of the NGC are posted at http://www.astro-tom.com/messier/messier_finder_charts/map1.pdf http://www.astro-tom.com/messier/messier_finder_charts/map1..pdf and http://www.saguaroastro.org/content/db/Book110BestNGC.pdf http://www.saguaroastro.org/content/db/Book110BestNGC.pdf respectively.
Information pertaining to observing some of the more prominent Messier galaxies can be found at http://www.cloudynights.com/topic/358295-how-to-locate-some-of-the-major-messier-galaxies-and-helpful-advice-for-novice-amateur-astronomers/ http://www.cloudynights.com/topic/358295-how-to-locate-some-of-the-major-messier-galaxies-and-helpful-advice-for-novice-amateur-astronomers/
Stellarium and Cartes du Ciel are two excellent freeware planetarium programs that are available at http://stellarium.org/ http://stellarium.org/ and https://www.ap-i.net/skychart/en/start https://www.ap-i.net/skychart/en/start
Deep-sky object list generators can be found at http://www.virtualcolony.com/sac/ http://www.virtualcolony.com/sac/ and http://tonightssky.com/MainPage.php http://tonightssky.com/MainPage.php and https://dso-browser.com/ https://dso-browser.com/
Freeware sky atlases can be downloaded at http://www.deepskywatch.com/files/deepsky-atlas/Deep-Sky-Hunter-atlas-full.pdf http://www.deepskywatch.com/files/deepsky-atlas/Deep-Sky-Hunter-atlas-full.pdf and http://astro.mxd120.com/free-star-atlases http://astro.mxd120.com/free-star-atlases
Eighty binary and multiple stars for May: 1 Bootis, Struve 1782, Tau Bootis, Struve 1785, Struve 1812 (Bootes); 2 Canum Venaticorum, Struve 1624, Struve 1632, Struve 1642, Struve 1645, 7 Canum Venaticorum, Alpha Canum Venaticorum (Cor Caroli), h2639, Struve 1723, 17 Canum Venaticorum, Otto Struve 261, Struve 1730, Struve 1555, h1234, 25 Canum Venaticorum, Struve 1769, Struve 1783, h1244 (Canes Venatici); 2 Comae Berenices, Struve 1615, Otto Struve 245, Struve 1633, 12 Comae Berenices, Struve 1639, 24 Comae Berenices, Otto Struve 253, Struve 1678, 30 Comae Berenices, Struve 1684, Struve 1685, 35 Comae Berenices, Burnham 112, h220, Struve 1722, Beta Comae Berenices, Burnham 800, Otto Struve 266, Struve 1748 (Coma Berenices); h4481, h4489, Struve 1604, Delta Corvi, Burnham 28, h1218, Struve 1669 (Corvus); H N 69, h4556 (Hydra); Otto Struve 244, Struve 1600, Struve 1695, Zeta Ursae Majoris (Mizar), Struve 1770, Struve 1795, Struve 1831 (Ursa Major); Struve 1616, Struve 1627, 17 Virginis, Struve 1648, Struve 1658, Struve 1677, Struve 1682, Struve 1689, Struve 1690, 44 Virginis, Struve 1719, Theta Virginis, 54 Virginis, Struve 1738, Struve 1740, Struve 1751, 81 Virginis, Struve 1764, Struve 1775, 84 Virginis, Struve 1788 (Virgo)
Notable carbon star for May: SS Virginis
One hundred and sixty-five deep-sky objects for May: NGC 5248 (Bootes); M3, M51, M63, M94, M106, NGC 4111, NGC 4138, NGC 4143, NGC 4151, NGC 4214, NGC 4217, NGC 4244, NGC 4346, NGC 4369, NGC 4449, NGC 4485, NGC 4490, NGC 4618, NGC 4631, NGC 4656, NGC 4868, NGC 5005, NGC 5033, NGC 5297, NGC 5353, NGC 5354, Up 1 (Canes Venatici); Mel 111, M53, M64, M85, M88, M91, M98, M99, M100, NGC 4064, NGC 4150, NGC 4203, NGC 4212, NGC 4251, NGC 4274, NGC 4278, NGC 4293, NGC 4298, NGC 4302, NGC 4314, NGC 4350, NGC 4414, NGC 4419, NGC 4448, NGC 4450, NGC 4459, NGC 4473, NGC 4474, NGC 4494, NGC 4559, NGC 4565, NGC 4651, NGC 4689, NGC 4710, NGC 4725, NGC 4874, NGC 5053 (Coma Berenices); NGC 4027, NGC 4038-9, NGC 4361 (Corvus); M68, M83, NGC 4105, NGC 4106, NGC 5061, NGC 5101, NGC 5135 (Hydra); M40, NGC 4036, NGC 4041, NGC 4051, NGC 4062, NGC 4085, NGC 4088, NGC 4096, NGC 4100, NGC 4144, NGC 4157, NGC 4605, NGC 5308, NGC 5322 (Ursa Major); M49, M58, M59, M60, M61, M84, M86, M87, M89, M90, M104, NGC 4030, NGC 4073, NGC 4168, NGC 4179, NGC 4206, NGC 4215, NGC 4216, NGC 4224, NGC 4235, NGC 4260, NGC 4261, NGC 4267, NGC 4281, NGC 4339, NGC 4343, NGC 4365, NGC 4371, NGC 4378, NGC 4380, NGC 4387, NGC 4388, NGC 4402, NGC 4429, NGC 4435, NGC 4438, NGC 4517, NGC 4526, NGC 4535, NGC 4536, NGC 4546, NGC 4550, NGC 4551, NGC 4567, NGC 4568, NGC 4570, NGC 4593, NGC 4596, NGC 4636, NGC 4638, NGC 4639, NGC 4643, NGC 4654, NGC 4666, NGC 4697, NGC 4698, NGC 4699, NGC 4753, NGC 4754, NGC 4760, NGC 4762, NGC 4866, NGC 4900, NGC 4958, NGC 5044, NGC 5054, NGC 5068, NGC 5077, NGC 5084, NGC 5087, NGC 5147, NGC 5170, NGC 5247, NGC 5363, NGC 5364 (Virgo)
Top ten deep-sky objects for May: M3, M51, M63, M64, M83, M87, M104, M106, NGC 4449, NGC 4565
Top ten deep-sky binocular objects for May: M3, M51, M63, M64, M84, M86, M87, M104, M106, Mel 111
Challenge deep-sky object for May: 3C 273 (Virgo)
The objects listed above are located between 12:00 and 14:00 hours of right ascension.
All times, unless otherwise noted, are UT (subtract four hours and, when appropriate, one calendar day for EDT)
5/2 Saturn (magnitude +0.5) is 2.7 degrees west of Pluto (magnitude +14.3) at 5:00; the Moon is 4.0 degrees north of Venus at 12:00; the Moon is 0.2 degree north of asteroid 4 Vesta, with an occultation occurring in southern Europe, northwestern Africa, the Cape Verde Islands, the Azores, northern South America, and the Galapagos Islands, at 13:00; the Moon is 3..4 degrees south-southeast of Venus at 15:00
5/3 The Moon is 2.7 degrees south-southeast of Mercury at 10:00; Mars and Saturn are at heliocentric opposition (longitudes 105.2 degrees and 285.2 degrees) at 14:00
5/4 The Moon is 4.4 degrees south-southeast of Uranus at 3:00; New Moon (lunation 1192) occurs at 22:46
5/5 Today is May Day or Beltane, a cross-quarter day; the peak of the Eta Aquarid meteor shower (20 per hour for northern hemisphere observers) occurs at 13:00
5/6 The Moon is 7.9 degrees south-southeast of the bright open cluster M45 (the Pleiades or Subaru) in Taurus at 5:00; the Moon is 2.2 degrees north of the first-magnitude star Aldebaran (Alpha Tauri) at 22:00
5/8 The Moon is 3.2 degrees south-southeast of Mars at 1:00; Mercury (magnitude -0.8) is 1.3 degrees south-southeast of Uranus (magnitude +5.9) at 16:00
5/9 The Moon is at descending node (longitude 109.3 degrees) at 19:00
5/10 The Moon is 6.3 degrees south of the first-magnitude star Pollux (Beta Geminorum) at 3:00; Venus is at its southernmost latitude from the ecliptic plane (-3.4 degrees) at 6:00
5/11 The Moon lies within the bright open cluster M44 (the Beehive Cluster or Praesepe) in Cancer at 2:00; the Lunar X (also known as the Werner or Purbach Cross), an X-shaped clair-obscure illumination effect involving various rims and ridges between the craters La Caille, Blanchinus, and Purbach, is predicted to be fully formed at 16:25; asteroid 8 Flora (magnitude +9.8) is at opposition at 23:00
5/12 First Quarter Moon occurs at 1:12; the Moon is 2.9 degrees north-northeast of the first-magnitude star Regulus (Alpha Leonis) at 17:00
5/13 The Moon is at perigee, subtending 32' 23'' from a distance of 369,009 kilometers (229,291 miles), at 21:53
5/14 The equation of time is at a maximum of 3.65 minutes at 9:00; asteroid 11 Parthenope (magnitude +9.5) is at opposition at 10:00; the Sun enters Taurus (longitude 53.47 degrees on the ecliptic) at 13:00
5/16 The Moon is 7.1 degrees north-northeast of the first-magnitude star Spica (Alpha Virginis) at 12:00; Mars is at its northernmost declination (24..6 degrees) at 22:00
5/18 Venus (magnitude -3.9) is 1.1 degrees south-southeast of Uranus (magnitude +5.9) at 17:00; Full Moon, known as the Milk or Planting Moon, occurs at 21:11
5/19 Mercury is at the ascending node through the ecliptic plane at 15:00; Mars is 0.2 degree north of the bright open cluster M35 in Gemini at 16:00; the Moon is 1.2 degrees south of the dwarf planet/asteroid 1 Ceres, with an occultation occurring in parts of Antarctica, at 18:00; the Moon is 7.8 degrees north-northeast of the first-magnitude star Antares (Alpha Scorpii) at 21:00
5/20 Asteroid 20 Massalia (magnitude +9.8) is at opposition at 13:00; the Moon is 1.7 degrees north-northeast of Jupiter at 18:00
5/21 The Sun’s longitude is 60 degrees at 8:00; Mercury is in superior conjunction (a distance of 1.322 a.u. from Earth and a latitude of 1.42 degrees) with the Sun at 13:00; Mercury is 3.7 degrees south-southeast of M45 at 15:00
5/22 The Moon is at the descending node (longitude 288.5 degrees) at 19:00; the Moon, Saturn, and Pluto lie within a circle with a diameter of 2.94 degrees at 23:00; the Moon is 0.5 degree south of Saturn, with an occultation occurring in southern New Zealand, most of Australia, the Kerguelen Islands, parts of eastern Antarctica, and the southern tip of Africa, at 22:00
5/23 The Moon is 0.1 degree south of Pluto, with an occultation occurring in southern and eastern Africa and central South America, at 4:00
5/24 Mercury is at perihelion (0.3075 a.u. from the Sun) at 7:00
5/25 Mercury is 6.5 degrees north-northwest of Aldebaran at 18:00
5/26 The Moon is at apogee, subtending 29' 34'' from a distance of 404,137 kilometers (251,119 miles), at 13:27; Last Quarter Moon occurs at 16:34
5/27 The Curtiss Cross, an X-shaped clair-obscure illumination effect located between the craters Parry and Gambart, is predicted to be visible at 19:32; the Moon is 3.5 degrees south-southeast of Neptune at 20:00
5/28 The dwarf planet/asteroid 1 Ceres (magnitude +7.0) is at opposition at 23:00
5/30 The Moon is 0.6 degree north of asteroid 4 Vesta, with an occultation occurring in northwestern North America, the Aleutian Islands, northwestern Micronesia, eastern Asia, and parts of Indonesia, at 22:00
5/31 The Moon is 4.5 degrees south-southeast of Uranus at 14:00
Nicolas Lacaille (1713-1762), Otto Wilhelm Struve (1819-1905), Joseph Lockyer (1836-1920), Williamina Fleming (1857-1911), and Frank Drake (1930) were born this month.
The first recorded perihelion passage of Comet Halley (1P/Halley) occurred on May 25, 240 BC. Thales of Miletus accurately predicted a solar eclipse on May 28, 585 BC. The German astronomers Gottfried and Maria Magarethe Kirch discovered the bright globular cluster M5 on May 5, 1702. On May 1, 1759, the English amateur astronomers John Bevis and Nicholas Munckley observed Comet Halley on its first predicted return. The French astronomer Charles Messier discovered the globular cluster M3 on May 3, 1764 and the globular cluster M10 on May 29, 1764. The Italian astronomer Annibale de Gasparis discovered asteroid 11 Parthenope on May 11, 1850. Asteroid 14 Irene was discovered on May 19, 1851 by the English astronomer John Russell Hind. The German astronomer Robert Luther discovered asteroid 26 Proserpina on May 6, 1853. The Australian astronomer John Tebbutt discovered the Great Comet of 1861 (C/1861 J1 and 1861 II) on May 13, 1861. The English astronomer Norman Pogson discovered asteroid 80 Sappho on May 2, 1864. Norman Pogson discovered asteroid 87 Sylvia on May 16, 1866. The 40-inch Clark refractor at the Yerkes Observatory saw first light on May 21, 1897. The Griffith Observatory opened to the public on May 14, 1935. Nereid, Neptune’s third-largest satellite, was discovered on May 1, 1949 by the Dutch-American astronomer Gerard Kuiper.
The broad peak of the Eta Aquarid meteor shower is not adversely affected by moonlight this year. Southern hemisphere observers are favored. Eta Aquarid meteors are debris from the famous periodic comet 1P/Halley. The radiant is located close to the Water Jug asterism in Aquarius. See https://www.amsmeteors.org/meteor-showers/meteor-shower-calendar/#eta+Aquariids https://www.amsmeteors.org/meteor-showers/meteor-shower-calendar/#eta+Aquariids and page 48 of the May 2019 issue of Sky & Telescope http://www.imo.net/2018-eta-aquariids-predictions-and-observations/for additional information on the Eta Aquarids.
Information on the few remaining Iridium satellite 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/ http://www.heavens-above.com/
The Moon is 25.5 days old, is illuminated 16.2%, subtends 29.3 arc minutes, and is located in Aquarius on May 1st at 0:00 UT. The Moon is at its greatest northern declination on May 9th (+22.2 degrees). The Moon is at its greatest its greatest southern declination on May 22nd (-22.3 degrees). Longitudinal libration is at maximum (+5.0 degrees) on May 19th and at minimum (-5.0 degrees) on May 6th. Latitudinal libration is at maximum (+6.6 degrees) on May 3rd and again (+6.7 degrees) on May 30th and at minimum (-6.6 degrees) on May 16th. The Moon is at apogee (distance 63.36 Earth-radii) on May 26th and at perigee (distance 57.86 Earth-radii) on May 13th. New Moon occurs on May 4th. The 39%-illuminated Moon transits M44 from 2:00 to 4:00 UT on May 11th. See https://occultations.org/campaigns/ https://occultations.org/campaigns/ for further information on this event. The Moon occults 4 Vesta on May 2nd and May 30th, 1 Ceres on May 19th, Saturn on May 22nd, and Pluto on May 23rd from certain parts of the world. Consult http://www.lunar-occultations.com/iota/iotandx.htm http://www.lunar-occultations.com/iota/iotandx.htm for more on lunar occultations. Visit http://saberdoesthestars.wordpress.com/2011/07/05/saber-does-the-stars/ http://saberdoesthestars.wordpress.com/2011/07/05/saber-does-the-stars/ for tips on spotting extreme crescent Moons. Click on http://www.calendar-12.com/moon_calendar/2019/may http://www.calendar-12.com/moon_calendar/2019/may for a lunar phase calendar. Times and dates for the lunar light rays predicted to occur this month are available at http://www.lunar-occultations.com/rlo/rays/rays.htm http://www.lunar-occultations.com/rlo/rays/rays.htm
The Sun is located in Aries on May 1st. It enters Taurus on May 14th.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on May 1st: Mercury (magnitude -0.4, 5.8", 75% illuminated, 1.15 a.u., Pisces), Venus (magnitude -3.8, 11.5", 88% illuminated, 1.45 a.u., Pisces), Mars (magnitude +1.6, 4.2", 96% illuminated, 2.24 a.u., Taurus), Jupiter (magnitude -2.5, 43.5", 100% illuminated, 4.54 a.u., Ophiuchus), Saturn (magnitude +0.5, 17.2", 100% illuminated, 9.67 a.u., Sagittarius), Uranus on May 16th (magnitude +5.9, 3.4", 100% illuminated, 20.79 a.u., Aires), Neptune on May 16th (magnitude +7.9, 2.3", 100% illuminated, 30.33 a.u., Aquarius), and Pluto on May 16th (magnitude +14.2, 0.1", 100% illuminated, 32.72 a.u., Sagittarius).
In the evening, Mercury is in the northwest and Mars is in the west. Jupiter is located in the southeast at midnight. Mercury, Venus, and Uranus can be seen in the east, Saturn in the south, Jupiter in the southwest, and Neptune in the southeast at dawn.
Mercury can be seen extremely low in the east during early part of the month. A very slender waning crescent Moon passes three degrees to the south of Mercury on May 3rd. Mercury is in superior conjunction on May 21st. As May ends, the speediest planet enters the evening sky and can be seen to the lower right of Mars in the west-northwest 30 minutes after the Sun sets. Mercury shines brightly at magnitude -1.2 at that time.
During May, Venus rises about an hour before the Sun and shines at its minimum brightness of magnitude -3.8. A thin waning crescent Moon passes four degrees south of the planet on May 2nd. Venus is at its greatest heliocentric latitude south on May 10th. Venus lies 1.2 degrees south of Uranus on May 18th.
Mars lies between the horns of Taurus, Beta and Zeta Tauri, on May 6th. A waxing crescent Moon passes three degrees south of the Red Planet on May 7th. Mars shrinks to 3.9 arc seconds and shines at only magnitude +1.8 by the end of May. Mars departs Taurus and enters Gemini by the middle of the month.
Jupiter increases in apparent size from 43.5 to 45.8 arc seconds this month. The waning gibbous Moon passes less than two degrees to the north of Jupiter on May 20th. The orbital plane of the Galilean satellites is currently inclined three degrees to our line of sight. A shadow transit by Ganymede begins at 3:42 a.m. EDT on the morning of May 7th. On the morning of May 18th, Ganymede reappears from occultation at 2:16 a.m. EDT. Io’s shadow begins to transit the planet at 3:44 a.m. EDT followed by Io itself at 4:17 a.m. EDT. Ganymede begins to disappear into eclipse to the west of Jupiter at 1:41 a.m. EDT on the morning of May 25th, an event that will take 14 minutes to transpire. Articles on observing Jupiter and the Great Red Spot (GRS) appear on pages 52 and 53 respectively of the May 2019 issue of Sky & Telescope. Browse http://www.skyandtelescope.com/observing/interactive-sky-watching-tools/ http://www.skyandtelescope.com/observing/interactive-sky-watching-tools/ or http://www.projectpluto.com/jeve_grs.htm http://www.projectpluto.com/jeve_grs.htm in order to determine transit times of Jupiter’s central meridian by the GRS. GRS transit information also appears on pages 50 and 51 of the May 2019 issue of Sky & Telescope. Data on the Galilean satellite events is available on page 51 of the May 2019 issue of Sky & Telescope and online at http://www.skyandtelescope.com/observing/interactive-sky-watching-tools/ http://www.skyandtelescope.com/observing/interactive-sky-watching-tools/ and http://www.projectpluto.com/jevent.htm http://www.projectpluto.com/jevent.htm
Saturn retrogrades through eastern Sagittarius this month. It shines at magnitude +0.4 and has an apparent equatorial diameter of almost 18 arc seconds at mid-month. Saturn’s rings subtend more than 40 arc seconds and are inclined by nearly 24 degrees at that time. In late May, Saturn nears the meridian as morning twilight begins. The waning gibbous Moon passes one half degree south of Saturn on May 22nd. Eighth-magnitude Titan, Saturn’s brightest satellite, is located south of the planet on May 4th and May 20th and north of it on May 12th and May 28th. Saturn’s odd satellite Iapetus shines faintly at eleventh magnitude when it passes north of Saturn on May 18th and May 19th. For further information on Saturn’s satellites, browse http://www.skyandtelescope.com/observing/interactive-sky-watching-tools/ http://www.skyandtelescope.com/observing/interactive-sky-watching-tools/
Uranus can be seen once again during morning twilight during the second half of May. Venus passes 1.2 degrees due south of Uranus on May 18th. On May 31st, the waning crescent Moon passes 4.5 degrees south-southeast of Uranus. The two celestial objects rise more than an hour before the Sun on that date.
Neptune is located 1.2 degrees east-northeast of the fourth-magnitude star Phi Aquarii in eastern Aquarius this month. The waning crescent Moon passes 3.5 degrees south-southeast of Neptune on May 27th. Neptune reaches an altitude of nearly 20 degrees in east-southeast as morning twilight begins on the final day of the month.
Pluto lies in northeastern Sagittarius and transits the meridian before dawn.
Comet C/2017 M4 (ATLAS) passes west-southwestward through Scorpius and into Lupus in May. This faint comet is located five degrees west of the third-magnitude star Mu1 Scorpii on May 1st. It passes a bit more than one degree north of the ninth-magnitude globular cluster NGC 6139 on May 3rd and 1.3 degrees south of the third-magnitude star Eta Lupi on May 13th. Visit http://cometchasing.skyhound.com/ http://cometchasing.skyhound.com/ and http://www.aerith.net/comet/weekly/current.html http://www.aerith.net/comet/weekly/current.html for information on comets visible this month.
The dwarf planet/asteroid 1 Ceres (magnitude +7.0) reaches opposition in western Ophiuchus on May 28th. Ceres retrogrades into Scorpius shortly thereafter. A finder chart can be found on page 48 of the May 2019 issue of Sky & Telescope. With a diameter of 940 kilometers (585 miles), Ceres is the largest object in the main asteroid belt and is the only asteroid to be differentiated, i.e., to have layers. Other asteroids brighter than magnitude +11.0 that reach opposition this month include 8 Flora (magnitude +9.8) on May 12th, 11 Parthenope (magnitude +9.5) on May 14th, 68 Leto (magnitude +10.7) on May 14th, 20 Massalia (magnitude +9.8) on May 20th, and 32 Pomona (magnitude +10.5) on May 27th. Information on asteroid occultations taking place this month is available at http://www.asteroidoccultation.com/2019_05_si.htm http://www.asteroidoccultation.com/2019_05_si.htm
For more on the planets and how to locate them, browse http://www.nakedeyeplanets.com/ http://www.nakedeyeplanets.com/
A wealth of current information on solar system celestial bodies is posted at http://www.curtrenz.com/astronomy.html http://www.curtrenz.com/astronomy.html and http://nineplanets.org/ http://nineplanets.org/
Various events taking place within our solar system are discussed at http://www.bluewaterastronomy.info/styled-4/index.html http://www.bluewaterastronomy.info/styled-4/index.html
Information on the celestial events transpiring each week can be found at http://astronomy.com/skythisweek http://astronomy.com/skythisweek and http://www.skyandtelescope.com/observing/sky-at-a-glance/ http://www.skyandtelescope.com/observing/sky-at-a-glance/
Free star maps for May can be downloaded at http://www.skymaps.com/downloads.html http://www.skymaps.com/downloads.html and https://www.telescope.com/content.jsp?pageName=Monthly-Star-Chart https://www.telescope.com/content.jsp?pageName=Monthly-Star-Chart
Data on current supernovae can be found at http://www.rochesterastronomy.org/snimages/ http://www.rochesterastronomy.org/snimages/
Finder charts for the Messier objects and other deep-sky objects are posted at https://freestarcharts.com/messier https://freestarcharts.com/messier and https://freestarcharts.com/ngc-ic https://freestarcharts.com/ngc-ic and http://www.cambridge.org/features/turnleft/seasonal_skies_april-june.htm http://www.cambridge.org/features/turnleft/seasonal_skies_april-june.htm
Telrad finder charts for the Messier Catalog and the SAC’s 110 Best of the NGC are posted at http://www.astro-tom.com/messier/messier_finder_charts/map1.pdf http://www.astro-tom.com/messier/messier_finder_charts/map1..pdf and http://www.saguaroastro.org/content/db/Book110BestNGC.pdf http://www.saguaroastro.org/content/db/Book110BestNGC.pdf respectively.
Information pertaining to observing some of the more prominent Messier galaxies can be found at http://www.cloudynights.com/topic/358295-how-to-locate-some-of-the-major-messier-galaxies-and-helpful-advice-for-novice-amateur-astronomers/ http://www.cloudynights.com/topic/358295-how-to-locate-some-of-the-major-messier-galaxies-and-helpful-advice-for-novice-amateur-astronomers/
Stellarium and Cartes du Ciel are two excellent freeware planetarium programs that are available at http://stellarium.org/ http://stellarium.org/ and https://www.ap-i.net/skychart/en/start https://www.ap-i.net/skychart/en/start
Deep-sky object list generators can be found at http://www.virtualcolony.com/sac/ http://www.virtualcolony.com/sac/ and http://tonightssky.com/MainPage.php http://tonightssky.com/MainPage.php and https://dso-browser.com/ https://dso-browser.com/
Freeware sky atlases can be downloaded at http://www.deepskywatch.com/files/deepsky-atlas/Deep-Sky-Hunter-atlas-full.pdf http://www.deepskywatch.com/files/deepsky-atlas/Deep-Sky-Hunter-atlas-full.pdf and http://astro.mxd120.com/free-star-atlases http://astro.mxd120.com/free-star-atlases
Eighty binary and multiple stars for May: 1 Bootis, Struve 1782, Tau Bootis, Struve 1785, Struve 1812 (Bootes); 2 Canum Venaticorum, Struve 1624, Struve 1632, Struve 1642, Struve 1645, 7 Canum Venaticorum, Alpha Canum Venaticorum (Cor Caroli), h2639, Struve 1723, 17 Canum Venaticorum, Otto Struve 261, Struve 1730, Struve 1555, h1234, 25 Canum Venaticorum, Struve 1769, Struve 1783, h1244 (Canes Venatici); 2 Comae Berenices, Struve 1615, Otto Struve 245, Struve 1633, 12 Comae Berenices, Struve 1639, 24 Comae Berenices, Otto Struve 253, Struve 1678, 30 Comae Berenices, Struve 1684, Struve 1685, 35 Comae Berenices, Burnham 112, h220, Struve 1722, Beta Comae Berenices, Burnham 800, Otto Struve 266, Struve 1748 (Coma Berenices); h4481, h4489, Struve 1604, Delta Corvi, Burnham 28, h1218, Struve 1669 (Corvus); H N 69, h4556 (Hydra); Otto Struve 244, Struve 1600, Struve 1695, Zeta Ursae Majoris (Mizar), Struve 1770, Struve 1795, Struve 1831 (Ursa Major); Struve 1616, Struve 1627, 17 Virginis, Struve 1648, Struve 1658, Struve 1677, Struve 1682, Struve 1689, Struve 1690, 44 Virginis, Struve 1719, Theta Virginis, 54 Virginis, Struve 1738, Struve 1740, Struve 1751, 81 Virginis, Struve 1764, Struve 1775, 84 Virginis, Struve 1788 (Virgo)
Notable carbon star for May: SS Virginis
One hundred and sixty-five deep-sky objects for May: NGC 5248 (Bootes); M3, M51, M63, M94, M106, NGC 4111, NGC 4138, NGC 4143, NGC 4151, NGC 4214, NGC 4217, NGC 4244, NGC 4346, NGC 4369, NGC 4449, NGC 4485, NGC 4490, NGC 4618, NGC 4631, NGC 4656, NGC 4868, NGC 5005, NGC 5033, NGC 5297, NGC 5353, NGC 5354, Up 1 (Canes Venatici); Mel 111, M53, M64, M85, M88, M91, M98, M99, M100, NGC 4064, NGC 4150, NGC 4203, NGC 4212, NGC 4251, NGC 4274, NGC 4278, NGC 4293, NGC 4298, NGC 4302, NGC 4314, NGC 4350, NGC 4414, NGC 4419, NGC 4448, NGC 4450, NGC 4459, NGC 4473, NGC 4474, NGC 4494, NGC 4559, NGC 4565, NGC 4651, NGC 4689, NGC 4710, NGC 4725, NGC 4874, NGC 5053 (Coma Berenices); NGC 4027, NGC 4038-9, NGC 4361 (Corvus); M68, M83, NGC 4105, NGC 4106, NGC 5061, NGC 5101, NGC 5135 (Hydra); M40, NGC 4036, NGC 4041, NGC 4051, NGC 4062, NGC 4085, NGC 4088, NGC 4096, NGC 4100, NGC 4144, NGC 4157, NGC 4605, NGC 5308, NGC 5322 (Ursa Major); M49, M58, M59, M60, M61, M84, M86, M87, M89, M90, M104, NGC 4030, NGC 4073, NGC 4168, NGC 4179, NGC 4206, NGC 4215, NGC 4216, NGC 4224, NGC 4235, NGC 4260, NGC 4261, NGC 4267, NGC 4281, NGC 4339, NGC 4343, NGC 4365, NGC 4371, NGC 4378, NGC 4380, NGC 4387, NGC 4388, NGC 4402, NGC 4429, NGC 4435, NGC 4438, NGC 4517, NGC 4526, NGC 4535, NGC 4536, NGC 4546, NGC 4550, NGC 4551, NGC 4567, NGC 4568, NGC 4570, NGC 4593, NGC 4596, NGC 4636, NGC 4638, NGC 4639, NGC 4643, NGC 4654, NGC 4666, NGC 4697, NGC 4698, NGC 4699, NGC 4753, NGC 4754, NGC 4760, NGC 4762, NGC 4866, NGC 4900, NGC 4958, NGC 5044, NGC 5054, NGC 5068, NGC 5077, NGC 5084, NGC 5087, NGC 5147, NGC 5170, NGC 5247, NGC 5363, NGC 5364 (Virgo)
Top ten deep-sky objects for May: M3, M51, M63, M64, M83, M87, M104, M106, NGC 4449, NGC 4565
Top ten deep-sky binocular objects for May: M3, M51, M63, M64, M84, M86, M87, M104, M106, Mel 111
Challenge deep-sky object for May: 3C 273 (Virgo)
The objects listed above are located between 12:00 and 14:00 hours of right ascension.
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