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SKY REPORTER: February 2011


Full Moon

The Full Moon.

Credit: Lick Observatory

On Tuesday February 1st, the Sun is within boundaries of the constellation Capricornus. At the end of February our nearest star is in Aquarius. The daily duration of time the Sun is above the horizon increases this month by a total of one hour and eight minutes.

February 1st sunrise in New York occurs at 7:05 a.m. and sunset is at 5:14 p.m. At the end of the month the sun rises at 6:31 and sets at 5:46. During February average overnight temperatures recorded in Central Park rise from 26 degrees Fahrenheit on the first, to 31 degrees on the 28th. Currently, Mars and Mercury are too close to the Sun’s direction for casual observations.

On February 1st, Jupiter, Uranus, and Neptune are all above the western horizon an hour after sunset. Jupiter is in the constellation Pisces and shines prominently at visual magnitude –2.2. Uranus (you-RAN-us) is also in Pisces and has an apparent magnitude 5.9. Neptune is at the border between Aquarius and Capricornus, and is near the horizon at the end of evening twilight. It is dim with a magnitude of just 8. At the start of February these planets set at the following times: Neptune 6:27 p.m., Uranus at 9 p.m., and Jupiter at 9:19.

Over at the opposite side of the horizon on February 1st, Saturn rises at 10:27 p.m., with magnitude 0.5. Venus enters the sky at 4:11 a.m. shining at magnitude minus 4.3. It remains a brilliant pre-dawn sight throughout this month. Aside from the Sun and Moon, no celestial object is as eye catching as Venus. Its brilliancy is such that many assume the planet’s vivid light is from an aircraft whose landing lights are aimed towards them.

By the end of February, Mercury, Mars, Uranus, and Neptune all are too close to the Sun for convenient viewing. On the last day of the month Jupiter is low in the west, ten degrees of arc above the horizon, one hour after sunset. The current observing season for Jupiter is then about to conclude. We must wait until May to again easily see this largest Solar System planet. Jupiter will reappear from the Sun’s dazzling zone of the ecliptic, and becomes visible in the pre-dawn sky.

Primary lunar phases this month begin with New Moon on Wednesday the 2nd. First Quarter phase is Friday the 11th. February’s Full Moon, known as the “Snow Moon” or “Hunger Moon” in Native American cultures, is Friday the 18th and Last Quarter phase is on Thursday, the 24th.

Passages of the moon cycling through its phases each month serve as markers of other sky objects. On the evening of Sunday February 6th a beautiful waxing crescent moon may be seen near Jupiter and Uranus. This night the three objects are about six degrees of arc apart. That approximates the same angular span as the width of three knuckles of your fist when seen at arm’s length. At about 6 p.m. on the 6th look above the western horizon for Jupiter, located almost directly to the left of the crescent moon. As the sky continues to darken, use binoculars or a telescope to seek Uranus, located between and lower than Jupiter and the Moon. The three will form a nearly equilateral triangle with Uranus marking the lower apex.

Jupiter and Europa

Jupiter as seen before last year's disappearance of its South Equatorial Belt. The Jovian moon Europa is at the image's right, with that satellite's shadow visible beneath the planet's SEB.

Credit: Cassini Imaging Team, Cassini Project, NASA

If you can access a telescope use this opportunity to enjoy the spectacular beauty of the lunar crescent as well as the fascinating Jovian moons. If you haven’t seen Jupiter with a telescope during the past year, have a look and note if one of its previously prominent equatorial belts is still missing! This structure has recently been reported as having started the process of reforming, so look for your own visual evidence of current developments. Also, if Uranus is not yet on your “life list” of planets, try for a glimpse of this dim seventh planet from the Sun. Remember, even if it’s cloudy on the evening of the 6th of February, and the moon will have moved further east during succeeding nights, Jupiter and Uranus shall be in approximately the same sky location for several additional weeks.

We recommend you also take advantage of crystal clear winter nights to enjoy the bright set of stars centered on the constellation Orion. Detailed charts of constellations usually depict far more stars than those that may be seen with unaided eyes in city skies. Therefore, urban observers are encouraged to concentrate on stars of first magnitude or brighter. This season, such luminaries include Betelgeuse (BATE-el-juice) and Rigel (RYE-jell) in Orion, Procyon (PRO-see-on) in Canis Minor, Capella, (ka-PELL-ah) overhead in the constellation Auriga (awe-RYE-ja), and Sirius (serious), brightest star in the entire night sky, located in Canis Major, the mythological Big Dog.

On the nights of the 13th and 14th of February, the waxing gibbous moon is seen in the midst of those brilliant stars. It is a region of active star formation containing objects that demonstrate progressive stages in stellar evolution.

During the night of Tuesday February 15 the bright gibbous moon is nine degrees of arc (a fist length) from Pollux (POL-lux), one of the notable “Twin Stars” in the constellation Gemini (GEM-in-ee). Due to the moon’s brilliance, cover it with your hand to better observe Pollux and Castor, its slightly fainter twin.

Pollux is a yellow star 34 light years from us. It has an apparent visual magnitude of 1.2 and is a giant ten times the Sun’s diameter. In addition to manufacturing energy by the thermonuclear process of fusing helium into carbon and oxygen in its core, Pollux also generates light and heat as a by-product of the transformation of hydrogen into helium within a shell surrounding the core. Pollux is orbited by a planet with a mass about three times that of Jupiter, in an orbit slightly bigger than the orbit of Mars. Pollux’s orbiting planet takes about one Earth year and seven months, to make a circuit of that star.

The evening of Friday January 18th when the Moon is Full it is about 222, 640 miles from Earth, located in our sky about 12 degrees southeast of the first magnitude Regulus, brightest star in the constellation Leo, the Lion.

On Monday February 21st, the waning gibbous moon is between the constellations Corvus and Virgo, just nine degrees (about a fist length) south of Saturn.

Around 5:30 a.m., on Monday the 28th of February, look for a thin waning crescent moon approximately 12 degrees above the southeastern horizon, to the upper right of Venus.

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