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May 2009 Celestial Calendar

Dave Mitsky

Note: All times in UTC (EST + 5)

The Eta Aquarid meteor shower is compromised by moonlight this year.

The Lunar X is visible twice this month, on May 2 beginning at 00:42 UT and on May 31 beginning at 11:53 UT. The Moon is located in Cancer and is 5.9 days old on May 1 at 0:00 UT. The Moon is at its greatest northern declination on May 25 (+26.5 degree) and its greatest southern declination on May 11 (-26.5 degrees). Longitudinal libration is at maximum (+5.0 degrees) on May 6 and at minimum (-7.1 degrees) on May 20. Latitudinal libration is at maximum (+6.6 degrees) on May 7 and at minimum (-6.6 degrees) on May 22. Times and dates for the lunar light rays predicted to occur in May 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 (-0.9 magnitude, 5.9", 75% illuminated, 1.13 a.u., Taurus), Venus (-3.9 magnitude, 9.9", 98% illuminated, 1.69 a.u., Pisces), Mars (1.2 magnitude, 5.8", 91% illuminated, 1.63 a.u., Pisces), Jupiter (-2.4 magnitude, 41.1", 99% illuminated, 4.79 a.u., Capricornus), Saturn (0.5 magnitude, 18.7", 100% illuminated, 8.89 a.u., Leo), Uranus (5.9 magnitude, 3.4", 100% illuminated, 20.53 a.u., Pisces), Neptune (7.9 magnitude, 2.3", 100% illuminated, 30.00 a.u., Capricornus), and Pluto (13.9 magnitude, 0.1", 100% illuminated, 30.63 a.u., Sagittarius).

Mercury is situated in the northwest and Saturn in the south in the evening; Saturn is located in the west at midnight; Jupiter and Neptune can be found in the southeast and Venus, Mars, and Uranus in the east at dawn. At midmonth, Saturn transits around 9:00 p.m. EDT and sets around 3:00 a.m. EDT, Jupiter rises around 2:00 a.m. EDT, and Venus and Mars rise around 4:00 a.m. EDT for observers at a latitude of 40 degrees north. Throughout May, five planets - Jupiter, Neptune, Uranus, Venus, and Mars - grace the dawn sky simultaneously from Capricornus to Pisces respectively.

Mercury's best evening northern hemisphere apparition of the year continues into early May. On May 1, Mercury lies just to the east of the bright open cluster M45 (the Pleiades). Mercury reaches inferior conjunction on May 18.

Venus remains a dawn object until the middle of May. At that time, Venus and Mars are a bit more than 6.5 degrees from each other but close to a span of less than 5.5 degrees by the end of the month.

Mars passes through Cetus briefly from May 1 to May 4 before returning to Pisces.

This month Jupiter is best seen about an hour before dawn. On May 20, Jupiter is just 0.1 degree south of the fifth-magnitude star Mu Capricorni. It passes 0.4 degree south of Neptune on May 25. Ganymede occults Io on May 4 at 5:35 a.m. EDT and Europa on May 11 at 4:19 a.m. EDT. Click on http://skyandtelescope.com/observing/objects/planets/article_107_1.asp to determine transit times of the central meridian by the Great Red Spot. Data on the Galilean satellites is available at http://skytonight.com/observing/objects/javascript/3307071.html

During May, the rings of Saturn are inclined 4 degrees with respect to the Earth, reaching a maximum tilt of 4.2 degrees on May 15, and span 42 arc minutes. Saturn is in retrograde, traveling westward, until May 17, when it is 15 degrees east of Regulus. On the mornings of May 7 and May 23, Titan is eclipsed by Saturn at 3:16 a.m. EDT and 2:23 a.m. EDT respectively. Shadow transits by Titan take place on the mornings of May 15 and May 31 at 1:26 and 12:32 a.m. EDT. For further information on Saturn’s satellites, browse http://skytonight.com/observing/objects/javascript/3308506.html

Uranus lies near the Circlet of Pisces, about five degrees to the south of the fifth magnitude star Lambda Piscium.

Neptune can be found about one degree northeast of the fifth-magnitude star Mu Capricorni.

The dwarf planet Pluto can be found in northwestern Sagittarius before sunrise.

Comet C/2008 T2 (Cardinal) passes through Gemini this month. From May 2 to May 4, the ninth-magnitude comet is less than two degrees from M35.

The ninth-magnitude asteroid 14 Irene passes 12 arc minutes south of the fourth magnitude star Tau Virginis on the evening of May 3 and even closer to north of the sixth-magnitude star 92 Virginis on May 9 .

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, Oto 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 variable star for May: R Hydrae (Hydra)

Notable carbon star for May: SS Virginis

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)