February 2011 Celestial Calendar & Observing Notes c/o Dave Mitsky

[Big Dipper]

February 2011 Celestial Calendar & Observing Notes courtesy of Dave Mitsky (calendar data also reproduced in our forum calendar).

All times, unless otherwise noted, are UT.

2/1 Jupiter is at its greatest heliocentric latitude south today; Mercury is 4 degrees south of the Moon at 18:00

2/3 Today is the actual date of the astronomical cross-quarter day of Candlemas; New Moon (lunation 1090) occurs at 2:31

2/4 Mars is in conjunction with the Sun at 16:00

2/5 Venus is 3 degrees north of the bright emission nebula M8 (the Lagoon Nebula) at 4:00

2/6 The Moon is at apogee, subtending 29 arc minutes from a distance of 405,924 kilometers (252,229 miles), at 23:12

2/7 Uranus is 6 degrees south of the Moon at 0:00; Jupiter is 7 degrees south of the Moon at 10:00

2/10 Asteroid 44 Nysa is at opposition at 13:00; the Lunar X (the Purbach or Werner Cross), an X-shaped illumination effect involving various rims and ridges between the craters La Caille, Blanchinus, and Purbach, is predicted to occur at 15:11

2/11 Mars is at its greatest heliocentric latitude south today; First Quarter Moon occurs at 7:18; the Moon is 1.4 degrees south of the bright open cluster M45 (the Pleiades) in Taurus at 22:00

2/14 The Moon is 1.0 degree south of the bright open cluster M35 in Gemini at 10:00

2/17 Neptune is in conjunction with the Sun at 10:00

2/18 Full Moon (known as the Hunger, Snow, or Storm Moon) occurs at 8:36

2/19 The Moon is at perigee, subtending 33 arc minutes from a distance of 358,247 kilometers (222,604 miles), at 7:24

2/20 Mercury is at its greatest heliocentric latitude south today

2/21 Saturn is 8 degrees north of the Moon at 17:00

2/24 Last Quarter Moon occurs at 23:26

2/25 Mercury is in superior conjunction at 9:00

2/26 The Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to occur at 16:42

2/28 Asteroid 4 Vesta (magnitude 7.0) is 0.9 degree north of the Moon, with an occultation taking place from Antarctica and the southern Pacific, at 0:00

Nicolas Copernicus (1473-1543), Galileo Galilei (1564-1642), and Clyde Tombaugh (1906-1997) were born this month.

During the first two weeks of February, the zodiacal light can be seen in the western sky after sunset from dark locations.

The Moon is 16.7 days old and is located in the constellation of Sagittarius at 0:00 UT on February 1. Since the Full Moon occurs near perigee, large tides will occur on February 18 through February 21. The Moon is at its greatest northern declination of +24.1 degrees on February 13 and its greatest southern declination of -24.0 degrees on February 25. Latitudinal libration is at a maximum of +6.6 degrees on February 20 and a minimum of -6.7 degrees on February 7. Longitudinal libration is at a maximum of +7.4 degrees on February 25 and a minimum of -7.6 degrees on February 13. The waxing gibbous Moon will occult the fourth-magnitude star Zeta Geminorum on the morning of February 15. See Bright Star Occultation for additional information on this event. Visit Extreme Lunar Crescent Data [L1090-1104] | Saber Does The Stars for tips on spotting extreme crescent Moons. Times and dates for the lunar light rays predicted to occur this month are available at Lunar Sunrise/Sunset Crater Rays

The Sun is located in the constellation of Capricornus on February 1. The Sun, the eight planets, and the dwarf planets Ceres and Pluto all lie south of the celestial equator for a few days as February begins.

Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on February 1: Mercury (magnitude -0.3, 5.1", 90% illuminated, 1.32 a.u., Sagittarius), Venus (magnitude -4.3, 19.6", 61% illuminated, 0.85 a.u., Sagittarius), Mars (magnitude 1.1, 3.9", 100% illuminated, 2.38 a.u., Capricornus), Jupiter (magnitude -2.2, 35.7", 99% illuminated, 5.52 a.u., Pisces), Saturn (magnitude 0.7, 18.2", 100% illuminated, 9.14 a.u., Virgo), Uranus (magnitude 5.9, 3.4", 100% illuminated, 20.76 a.u., Pisces), Neptune (magnitude 8.0, 2.2", 100% illuminated, 30.96 a.u., Aquarius), and Pluto (magnitude 14.1, 0.1", 100% illuminated, 32.77 a.u., Sagittarius).

Jupiter and Uranus can be seen in the west in the evening. Saturn lies in the east at midnight. Mercury is in the southeast and Saturn is in the southwest in the morning sky.

Visibility of the classical planets at midmonth from 40 degrees north latitude: Mercury can be seen during morning twilight; Venus rises at 4:00 a.m. EST; Jupiter sets at 9:00 p.m. EST; Saturn rises at 10:00 p.m. EST and transits at 3:00 a.m. EST.

Mercury is situated seven degrees above the horizon on the morning of February 1. The speedy planet is seven degrees from a thin crescent Moon on February 11 and four degrees from an even thinner crescent Moon the next morning. Mercury is in superior conjunction on February 25. During February, Mercury brightens from magnitude -0.2 to magnitude -0.6.

As Venus traverses northern Sagittarius this month, it passes close to the bright nebulae M8 and M20 on February 4 and February 5, midway between the globular cluster M22 and the open cluster M25 on February 11, and within ten arc minutes of the third-magnitude star Pi Sagittarii on February 18. Venus is seven degrees to the lower left of the waning crescent Moon on the morning of February 28. Venus declines in magnitude, from magnitude -4.3 to -4.1, and apparent size, from 20 to 16 arc seconds, as the month progresses but increases in illuminated extent from 61 to 71%.

Mars reaches conjunction on February 4 and is not observable.

Jupiter drops to magnitude -2.1 and decreases in apparent size to 34 arc seconds by month's end. It enters the northern celestial hemisphere on February 5. All four of the Galilean satellites are situated to the east of Jupiter that evening. On February 18, Io, Europa, Ganymede, and Callisto all lie to the west of the planet. Jupiter sets at approximately 8:00 p.m. EST by the end of the month. When February ends, Jupiter won't be a good telescopic target again until July. Click on SkyandTelescope.com - Planets - Transit Times of Jupiter's Great Red Spot to determine transits of the central meridian by the Great Red Spot. Data on the Galilean satellites is available at SkyandTelescope.com - Interactive Observing Tools - Jupiter's Moons Javascript Utility

The tilt angle of Saturn's rings increases to ten degrees this month. On February 14, the rings subtend 42 arc seconds. Eight-magnitude Titan is due north of Saturn on February 5 and February 21 and due south of the planet on February 12 and February 28. The tenth-magnitude satellites Tethys, Dione, and Rhea form a compact triangle to Saturn's east on the morning of February 5. Enceladus shines at twelfth-magnitude and is positioned to the east of Saturn's rings on the same morning. Twelfth-magnitude Iapetus is nine arc minutes from Saturn when it reaches greatest eastern elongation on the morning of February 14. For further information on Saturn's satellites, browse SkyandTelescope.com - Interactive Observing Tools - Saturn's Moons Javascript Utility

Uranus forms a compact triangle with the stars 27 and 29 Piscium this month. The distance between Uranus and Jupiter increases from four to eight degrees during February.

Neptune is in conjunction with the Sun on February 14 and is not visible this month.

Pluto is not readily observable during February.

This month a now very dim Comet 103P/Hartley travels northeastward through Monoceros. On February 1, it passes less than a degree east of the open cluster M50. Visit Comet Chasing for additional information on comets visible in February.

Asteroid 4 Vesta (magnitude 7.8) is about 0.4 degree northeast of Venus on the morning of February 9. The two objects follow almost parallel paths through Sagittarius during the first half of the month. Asteroid 7 Iris shines at eighth-magnitude as it travels westward through southwestern Cancer. It lies just south of the fifth-magnitude star 8 Cancri on February 5. A number of asteroid occultations visible from the United States take place this month. Click on Feb 2011 Asteroid Occultation Path Predictions for further information on these events.

A free star map for February can be downloaded at Skymaps.com - Publication Quality Sky Maps & Star Charts