Telescope Reviews: May 2011 Celestial Calendar

May Celestial Calendar by Dave Mitsky

All times, unless otherwise noted, are UT (subtract four hours and, when appropriate, one calendar day for EDT)

5/1 May Day or Beltane, a cross-quarter day; Mercury is 8 degrees south of the Moon at 7:00; Mars is 0.4 degree north of Jupiter at 11:00; Jupiter is 6 degrees south of the Moon at 19:00; Mars is 6 degrees south of the Moon at 20:00
5/3 New Moon (lunation 1093) occurs at 6:51
5/6 The peak of the Eta Aquarid meteor shower (20/hour) occurs at 12:00
5/7 The Moon is 1.7 degrees south of the bright open cluster M35 in Gemini at 7:00; Mercury is at greatest western elongation (27 degrees) at 19:00
5.8 Mercury is 1.4 degrees south of Venus at 3:00
5/10 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 05:56; First Quarter Moon occurs at 20:33; Mercury is 2 degrees south of Jupiter at 22:00
5/11 Venus is at its greatest heliocentric latitude south today; Venus is 0.6 degree south of Jupiter at 9:00
5/13 Asteroid 10 Hygiea (magnitude 9.2) is at opposition at 10:00
5/14 Saturn is 8 degrees north of the Moon at 15:00; a double Galilean satellite transit (Io follows Europa) occurs at 18:41
5/15 The Moon is at perigee, subtending 33 arc minutes from a distance of 362,135 kilometers (225,020 miles), at 11:24
5/17 Full Moon, known as the Milk or Planting Moon, occurs at 11:09
5/18 A double Galilean satellite transit (Io follows Europa) occurs at 7:39; Mercury is 1.4 degrees south of Venus at 8:00
5/19 Mercury is at its greatest heliocentric latitude south today
5/20 Mercury is 2 degrees south of Mars at 1:00
5/21 A double Galilean satellite transit (Io follows Europa) occurs at 20:36
5/22 Venus is 1.1 degrees south of Mars at 15:00
5/24 Last Quarter Moon occurs at 18:52; Neptune is 6 degrees south of the Moon at 18:00
5/25 A double Galilean satellite transit (Io follows Europa) occurs at 9:33; asteroid 2 Pallas (magnitude 9.2) is stationary at 15:00
5/26 The Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to begin at 6:26
5/27 The Moon is at apogee, subtending 29 arc minutes from a distance of 404,003 kilometers (251,657 miles), at 9:57; Uranus is 6 degrees south of the Moon at 13:00
5/28 A double Galilean satellite transit (Io follows Europa) occurs at 22:30
5/29 Jupiter is 6 degrees south of the Moon at 15:00
5/30 Mars is 4 degrees south of the Moon at 20:00
5/31 Venus is 4 degrees south of the Moon at 4:00

Nicolas Lacaille (1713-1762) and Joseph Lockyer (1836-1920) were born this month.

The peak of the Eta Aquarid meteor shower on May 6 is not affected by moonlight. This shower favors southern observers. Eta Aquarid meteors are debris from the famous periodic comet 1P/Halley.

The Moon is located in Pisces and is 27.3 days old on May 1 at 0:00 UT. At dawn on May 1, in order of decreasing altitude, the thin crescent Moon, Venus, Mercury, and a close pairing of Mars and Jupiter may be visible through binoculars shortly before sunrise. A waning crescent Moon joins those planets once again in the dawn sky from May 29 to May 31. The Moon is at its greatest northern declination on May 6 (+23.4 degrees) and its greatest southern declination on May 18 (-23.4 degrees). Longitudinal libration is at maximum (+6.4 degrees) on May 21 and at minimum (-6.6 degrees) on May 8. Latitudinal libration is at maximum (+6.8 degrees) on May 13 and at minimum (-6.9 degrees) on May 26. See http://www.lunar-occultations.com/iota/planets/0516venus.htm for information on lunar occultations. Visit http://www.astronomyblogs.com/member/saberscorpx/?xjMsgID=50821 for tips on spotting extreme crescent Moons. 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

The Sun is located in Aries on May 1.

Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on May 1: Mercury (magnitude 0.8, 9.2", 31% illuminated, 0.73 a.u., Pisces), Venus (magnitude -3.8, 11.6", 88% illuminated, 1.43 a.u., Pisces), Mars (magnitude 1.2, 4.0", 99% illuminated, 2.32 a.u., Pisces), Jupiter (magnitude -2.1, 33.4", 100% illuminated, 5.90 a.u., Pisces), Saturn (magnitude 0.5, 19.1", 100% illuminated, 8.72 a.u., Virgo), Uranus (magnitude 5.9, 3.4", 100% illuminated, 20.89 a.u., Pisces), Neptune (magnitude 7.9, 2.3", 100% illuminated, 30.36 a.u., Aquarius), and Pluto (magnitude 14.0, 0.1", 100% illuminated, 31.68 a.u., Sagittarius).

Saturn is in the southeast in the evening and in the southwest at midnight. Mercury, Venus, Mars, Jupiter, and Uranus can be found in the east and Neptune in southeast at dawn.

At midmonth, Mercury can be seen at morning twilight by observers at latitude 40 degrees north. Venus, Mars, and Jupiter rise at 5:00 a.m., and Saturn transits at 10:00 p.m. and sets at 4:00 a.m. local time at midmonth for people living at latitude 40 degrees north.

May is a very favorable month for observing planetary close encounters. Mercury, Venus, Mars, Jupiter, and Uranus are all located in Pisces during early May. The first four of those planets lie within a ten-degree circle for the first three weeks of the month. Between May 7 and May 15, they are less than eight degrees apart. Mercury, Venus, Mars, and Jupiter fit into a circle having a diameter of six degrees on May 12. Two planetary trios, i.e., three planets within five degrees of each other, take place this month. The Jupiter-Venus-Mercury trio is 2.1 degrees in diameter on May 7 and May 15. The three planets lie within three degrees of each from May 9 to May 13. The Venus-Mercury-Mars trio lasts for 10 days and is the tighter of the two, spanning a bit more than two degrees on May 21. Mercury, Venus, and Mars lie within three degrees of each other from May 19 to May 23. See http://media.skyandtelescope.com/video/planet-animation-may2011.mov for an animation showing May's dance of the planets.

Mercury reaches greatest western elongation on May 7. This apparition favors southern hemisphere observers. The speedy planet brightens from magnitude 0.8 to magnitude -0.9 as it decreases in apparent size from 9.2 to 5.5 arc seconds.

Venus is also better seen from the southern hemisphere due to the angle of the ecliptic. Venus and Mercury lie within 1.5 degrees of each for a remarkable two weeks beginning on May 7. The two planets are no farther than two degrees apart from May 4 through May 22. Brilliant Venus passes 0.6 degree south of Jupiter on May 11, one degree south of Mars on May 22, and four degrees south of the Moon on May 31. In mid-May, it shines at magnitude -3.8 but subtends only 11 arc seconds.

Mars shines faintly at magnitude 1.2 and is 0.4 degree north of Jupiter on May 1 and one degree north of Venus on May 22.

Jupiter is positioned low in the morning sky at the beginning of May. Southern hemisphere observers are favored once again. Jupiter shines at magnitude -2.1 and spans 33.9 arc seconds on May 15. Click on http://www.skyandtelescope.com/observing/objects/planets/3304091.html?page=1&c=y to determine transit times of the central meridian by the Great Red Spot. Data on the Galilean satellites is available at http://www.skyandtelescope.com/observing/objects/javascript/3307071.html

This month Saturn grows ever closer to the third-magnitude binary star Gamma Virginis, as the planet retrogrades through Virgo. It decreases in brightness from magnitude 0.5 to magnitude 0.7. During May, Saturn’s ring plane achieves an inclination of eight degrees. Saturn’s rings subtend 43 arc seconds. Eighth-magnitude Titan is due south of Saturn on May 3 and May 19. Saturn’s brightest satellite is due north of the planet on May 11 and May 27. On the morning of May 22, Titan, Rhea, and Tethys are situated to the west of Saturn and Enceladus and Dione to the east. Eleventh-magnitude Iapetus is close to the planet on the night of May 22. For further information on Saturn’s satellites, browse http://skytonight.com/observing/objects/javascript/3308506.html

Uranus is located in southern Pisces but is only 15 degrees above the horizon at dawn by the end of May.

Neptune is positioned less than half a degree to the southeast of 38 Aquarii for the entire month. It rises about 3:00 a.m. local daylight time at the start of the month. Nereid, Neptune’s third-largest satellite, was discovered on May 1, 1949 by Gerard Kuiper.

This month Pluto is located in northern Sagittarius, less than two degrees to the southeast of the open cluster M25. It rises at approximately 11:00 p.m. local time by the middle of the month. Pluto passes just north of the star SAO 161540 (magnitude 5.6) on May 5. The dwarf planet travels westward at approximately 0.9 arc minute per day.

The tenth-magnitude comet C/2009 P1 (Garradd) glides northward through Aquarius this month. It passes by the sixth-magnitude stars 81 and 82 Aquarii between May 17 and May 20. Visit http://cometchasing.skyhound.com/ for additional information on this and other comets visible during May.

Asteroid 10 Hygiea reaches opposition on May 13. From May 6 to May 22, this C-type asteroid will shine at magnitude 9.2, as it passes northwestward through southern Libra. Asteroid 7 Iris shines a bit less brightly at tenth-magnitude, as it travels through southern Cancer. It passes quite close to 45 Cancri on May 10, just north of the open cluster M67 on May 17, and only four arc minutes south of the fourth-magnitude star Alpha Cancri on May 22. Information on stellar occultations by asteroid 217 Eudora on the morning of May 29 and by asteroid 4569 Baerbel on the morning of May 30 can be found at http://www.asteroidoccultation.com/IndexAll.htm

A free star map for May can be downloaded at http://www.skymaps.com/downloads.html

The famous eclipsing variable star Algol (Beta Persei) is at a minimum, decreasing in magnitude from 2.1 to 3.4, on May 1, 4, 7, 9, 12, 15, 18, 21, 24, 27, and 30. For more on Algol, see http://stars.astro.illinois.edu/sow/Algol.html and http://www.solstation.com/stars2/algol3.htm

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)

Challenge binary star for May: 48 Virginis

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.