February 2012 Celestial Calendar & Observing Notes c/o Dave Mitsky

[Big Dipper]

February 2012 Celestial Calendar & Observing Notes courtesy of Dave Mitsky

(calendar data also reproduced in our forum calendar).

*NB: Check out also the resources at the end of Dave's calendar for further reading/information*

All times, unless otherwise noted, are UT.

2/4 Today is the actual date of the astronomical cross-quarter day known as Imbolc or Candlemas

2/7 Mercury is at its greatest heliocentric latitude south today; Mercury is in superior conjunction at 9:00; Full Moon (known as the Hunger, Snow, or Storm Moon) occurs at 21:54

2/8 Saturn is stationary at 12:00

2/10 Venus is 0.3 degree north of Uranus at 5:00; Mars is 10 degrees north of the Moon at 12:00

2/11 The Moon is at perigee, subtending 32'4" from a distance of 367,922 kilometers (231,619 miles), at 19:00

2/12 The Moon is 1.7 degrees south of the first-magnitude star Spica (Alpha Virginis) at 13:00

2/13 Saturn is 6 degrees north of the Moon at 1:00

2/14 Last Quarter Moon occurs at 17:04

2/15 Mars is at aphelion (1.66598 a.u. distant from the Sun) today

2/16 Venus is at the ascending node today; the Curtiss Cross, an X-shaped clair-obscure illumination effect located between the craters Parry and Gambart, is predicted to occur at 1:42

2/19 Neptune is in conjunction with the Sun at 21:00

2/21 New Moon (lunation 1103) occurs at 22:35

2/22 Asteroid 2 Pallas is in conjunction with the Sun at 18:00

2/23 Mercury is 6 degrees south of the Moon at 6:00

2/24 Uranus is 6 degrees south of the Moon at 13:00

2/25 Venus is 3 degrees south of the Moon at 22:00

2/26 Mercury is at the ascending node today

2/27 Jupiter is 4 degrees south of the Moon at 6:00; the Moon is at apogee, subtending 29'32" from a distance of 404,862 kilometers (251,345 miles), at 14:00; asteroid 6 Hebe (magnitude 9.4) is at opposition at 17:00

2/29 The Lunar X (the Purbach or Werner Cross), an X-shaped clair-obscure illumination effect involving various rims and ridges between the craters La Caille, Blanchinus, and Purbach, is predicted to occur at 13:54

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 8.7 days old and is located in the constellation of Aries at 0:00 UT on February 1. The waxing crescent Moon has close pairings with Venus on the evening of February 25 and Jupiter on the night of February 26. The Moon is at its greatest northern declination of +22.4 degrees on February 3 and its greatest southern declination of -22.3 degrees on February 16. Latitudinal libration is at a maximum of +4.7 degrees on February 20 and a minimum of -5.8 degrees on February 5. Longitudinal libration is at a maximum of +6.6 degrees on February 9 and a minimum of -6.6 degrees on February 22. Visit Saber Does The Stars saberdoesthestars 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.

Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on February 1: Mercury (magnitude -1.1, 4.8", 99% illuminated, 1.41 a.u., Sagittarius), Venus (magnitude –4.1, 15.1", 74% illuminated, 1.11 a.u., Sagittarius), Mars (magnitude -0.6, 11.8", 96% illuminated, 0.79 a.u., Capricornus), Jupiter (magnitude –2.3, 39.2", 99% illuminated, 5.03 a.u., Aries), Saturn (magnitude 0.6, 17.6", 100% illuminated, 9.45 a.u., Virgo), Uranus (magnitude 5.9, 3.4", 100% illuminated, 20.69 a.u., Pisces), Neptune (magnitude 8.0, 2.2", 100% illuminated, 30.93 a.u., Aquarius), and Pluto (magnitude 14.1, 0.1", 100% illuminated, 32.99 a.u., Sagittarius).

Mercury, Venus, and Uranus can be seen in the west and Jupiter in the southwest in the evening sky. Mars and Saturn lie in the southeast at midnight. Mars is in the west and Saturn is in the southwest in the morning sky.

Visibility of the classical planets at local time from 40 degrees north latitude at mid-month: Venus sets at 9:00 p.m.; Mars rises at 7:00 p.m. and transits at 2:00 a.m.; Jupiter sets at 11:00 p.m.; Saturn rises at 11:00 p.m. and transits at 4:00 a.m.

Mercury is visible low in the west at evening twilight during the last third of the month. The speediest planet sets about one hour after the sun does by February 22. A young crescent Moon lies about 5 degrees to the right of the planet that evening. By February 28, Mercury is greater than ten degrees above the western horizon 30 minutes after sunset. This will be the best evening apparition of Mercury for the year.

Venus grows in apparent size from 15.1 to 18.2 arc seconds but decreases in illuminated extent from 74% to 64%, as the month progresses. The most brilliant of the planets sets about two minutes later each day. By the end of February, Venus can be seen until 9:30 p.m. local time. Venus has close encounters with Uranus on February 10 and the Moon on February 25.

During February, Mars increases dramatically in brightness from magnitude -0.5 to magnitude -1.2 and gains two arc seconds in apparent size. Mars departs Virgo and reenters Leo on February 4. On February 19, the apparent brightness of the planet exceeds magnitude -1.0. Retrograde (westward) motion carries Mars to within 16 degrees of the first-magnitude star Regulus (Alpha Leonis) this month. At the end of February, Mars is approximately five degrees south of the third-magnitude star Theta Leonis. Information on the 2012 apparition of Mars can be found at Mars and Mars 2011/2012

Jupiter drops to magnitude -2.2 and declines in apparent size to 36.2 arc seconds by month’s end. Browse Transit Times of Jupiter's Great Red Spot - Planets - SkyandTelescope.com in order to determine transit times of Jupiter’s central meridian by the Great Red Spot. Data on the Galilean satellites is available at Jupiter's Moons Javascript Utility - Interactive Observing Tools - SkyandTelescope.com

Saturn begins retrograde motion on February 8. The tilt angle of Saturn's rings reaches 15 degrees this month. Eight-magnitude Titan is north of Saturn on February 7 and February 23 and south of the planet on February 15. Tenth-magnitude Iapetus is almost nine arc minutes west of Saturn when it reaches greatest eastern elongation on February 8. For further information on the satellites of Saturn, browse Saturn's Moons Javascript Utility - Interactive Observing Tools - SkyandTelescope.com

Uranus is just one third of a degree south of Venus on February 10. Gerald Kuiper discovered the Uranian satellite Miranda (magnitude 15.8) on February 16, 1948.

Neptune is in conjunction with the Sun on February 19 and is not observable this month.

The dwarf planet Pluto is not readily observable during February. Clyde Tombaugh discovered Pluto on February 18, 1930.

For more on the planets and how to locate them, browse The Naked Eye Planets in the Night Sky (and how to identify them)

During February, Comet C/2009 P1 (Garradd) shines at seventh magnitude and glides through Hercules and Draco before entering Ursa Minor. It passes less than one degree from the globular cluster M92 on February 2 and February 3. Visit Comet Chasing for additional information on comets visible in February.

Asteroid 433 Eros travels southwestward through Sextans and Hydra this month. It shines at magnitude 8.6 from February 1 to February 13 and decreases in brightness to magnitude 9.0 by February 25. An ephemeris is posted at Asteroids 03 and a finder chart can be found on page 52 of the February issue of Sky & Telescope. There’s an article about 433 Eros on pages 48 and 49 of the February issue of Astronomy. Asteroid 5 Astraea takes a northwestward path through Virgo during February. The ninth-magnitude main belt asteroid is due south of the fourth-magnitude star Mu Virginis on February 29.

Free star maps for February can be downloaded at Skymaps.com - Publication Quality Sky Maps & Star Charts and Orion Telescopes: Monthly Star Chart

The famous eclipsing variable star Algol (Beta Persei) is at a minimum, decreasing in magnitude from 2.1 to 3.4, on February 3, 6, 9, 12, 15, 17, 20, 23, 26, and 29. Consult The Minima of Algol - Variable Stars - SkyandTelescope.com for the times of the eclipses. For more on Algol, see Algol and Algol / Beta Persei 3

Forty binary and multiple stars for February: 41 Aurigae, Struve 872, Otto Struve 147, Struve 929, 56 Aurigae (Auriga); Nu-1 Canis Majoris, 17 Canis Majoris, Pi Canis Majoris, Mu Canis Majoris, h3945, Tau Canis Majoris (Canis Major); Struve 1095, Struve 1103, Struve 1149, 14 Canis Minoris (Canis Minor); 20 Geminorum, 38 Geminorum, Alpha Geminorum (Castor), 15 Geminorum, Lambda Geminorum, Delta Geminorum, Struve 1108, Kappa Geminorum (Gemini); 5 Lyncis, 12 Lyncis, 19 Lyncis, Struve 968, Struve 1025 (Lynx); Epsilon Monocerotis, Beta Monocerotis, 15 (S) Monocerotis (Monoceros); Struve 855 (Orion); Struve 1104, k Puppis, 5 Puppis (Puppis)

Notable carbon star for February: BL Orionis (Orion)

Fifty deep-sky objects for February: NGC 2146, NGC 2403 (Camelopardalis); M41, NGC 2345, NGC 2359, NGC 2360, NGC 2362, NGC 2367, NGC 2383 (Canis Major); M35, NGC 2129, NGC 2158, NGC 2266, NGC 2355, NGC 2371-72, NGC 2392, NGC 2420 (Gemini); NGC 2419 (Lynx); M50, NGC 2232, NGC 2237, NGC 2238, NGC 2244, NGC 2245, NGC 2251, NGC 2261, NGC 2264, NGC 2286, NGC 2301, NGC 2311, NGC 2324, NGC 2335, NGC 2345, NGC 2346, NGC 2353 (Monoceros); NGC 2169, NGC 2174, NGC 2194 (Orion); M46, M47, M93, Mel 71, NGC 2421, NGC 2423, NGC 2438, NGC 2439, NGC 2440, NGC 2467, NGC 2506, NGC 2509 (Puppis)

Top ten binocular deep-sky objects for February: M35, M41, M46, M47, M50, M93, NGC 2244, NGC 2264, NGC 2301, NGC 2360

Top ten deep-sky objects for February: M35, M41, M46, M47, M50, M93, NGC 2261, NGC 2362, NGC 2392, NGC 2403

Challenge deep-sky object for February: IC 443 (Gemini)

The objects listed above are located between 6:00 and 8:00 hours of right ascension.

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*Suggestions for further reading/information:*

Check out the following two sites (both are primarily UK-based) - each of which contain excellent celestial guides for the month ahead:

Astronomical Calendar

Astronomy.co.uk (site includes a short video highlighting some of the main celestial events for the month ahead).