SKY HAPPENINGS

The Sky for February 2014
By Faylene Roth

Naked eye viewing of the Beehive Cluster (aka Praesepe) provides a good measure of the darkness of night skies. This open cluster of a thousand stars formed together 600 million years ago in a gaseous nebula which we see as a hazy cloud near the center of Cancer. It is much younger than our 4.6 billion-year-old Sun. Four faint stars in the shape of an inverted “Y” form the constellation Cancer, located about half-way between Jupiter (center of Gemini) and Regulus (brightest star in Leo). Look for the Beehive about 3° NW of the center star in the “Y.” Binoculars reveal individual stars.

DAYLENGTH
February provides 2-3 minutes of additional sunlight each day. By the end of the month the days are an hour longer than on the same day of January. The effect of twilight also contributes to the length of usable daylight. Civil twilight begins as the sun sets and continues about one half hour. Nautical twilight takes over as color and detail disappear from the surrounding landscape and overhead skies darken. Astronomical twilight begins about one hour after sunset as skies continue to darken and lasts another 30 minutes before the western horizon darkens and night begins. The reverse progression occurs in the eastern sky with sunrise.

MOON HAPPENINGS
February 6 – First Quarter Moon brightens western sky until after midnight.
February 14– Full Moon rises at 6:02pm and occurs at 5:53 pm.
February 22 – Last Quarter Moon rises several hours after midnight.
(The time of moonrise and moonset assumes a flat horizon. Actual time may vary.)

ZODIACAL LIGHT
The zodiacal light becomes apparent before and after each equinox. Don’t confuse it with light domes that often appear above nearby towns and cities. The zodiacal light results from sunrays shooting straight up into the sky, perpendicular to the direction of the western horizon. Its cone-shaped pyramid of hazy white light differs from the rounded dome of urban lights and appears after the reds and golds of sunset fade away. Look for the zodiacal light in the western evening sky as astronomical twilight ends (see DAYLENGTH). It remains visible for about one hour.

METEOR EVENTS
No major meteor showers occur during February but watch for fireballs along the ecliptic. These bright meteors often blaze across the sky without the signature tail that accompanies most meteors.

Note: Hold your hand at arm’s length to measure apparent distances in the sky. The width of the little finger approximates 1.5̊. Middle, ring, and little finger touching represent about 5̊. The width of a fist is about 10̊. The fist with the thumb extended at a right angle equals 15̊. The hand stretched from thumb to little finger approximates 20̊-25̊. The diameter of both the full moon and the sun spans only 0.5̊. Adjust for the size of your hand.

Primary Sources: USGS; U.S. Naval Observatory; Your Sky at http://www.fourmilab.ch/yoursky/
To find out when the space shuttle and International Space Station are visible from your location, go to: http://spaceflight.nasa.gov/realdata/sightings/index.html and click on Sighting Opportunities.

VISIBLE PLANETS
Jupiter-Jupiter dominates the night sky in Gemini, but it also appears within a hexagon of six of the brightest stars in the night sky: (left then clockwise—Pollux (Gemini), Capella (Auriga), reddish Aldebaran (Taurus), blueish Rigel (Orion), Sirius (Canis Major), and Procyon (C. Minor). Betelgeuse is the red star about 20° right of Jupiter. Jupiter rises midafternoon which puts it high in the sky by evening twilight. It sets before morning twilight brightens the eastern sky. (Magnitude -2.5)

Mars- Mars rises before midnight in the southeastern sky ahead of blue-tinged Spica (Virgo) and reaches high overhead by morning twilight. It increases in brilliance throughout the month as it swings around from the far side of the sun and moves closer to earth. By month’s end, Mars will outshine 1st magnitude Spica. (Magnitude -0.4)

Mercury- Mercury shines brilliantly in the western sky as it approaches perihelion (nearest to sun) on February 3. Look for it low on the horizon on February 1—near a waxing sliver of moon. Mercury disappears into the Sun’s glare within a few days as it reaches inferior conjunction (passage between Earth and Sun) on February 15. (Magnitude -0.5)

Saturn- Saturn rises after midnight in the southeastern sky in Libra. Look for it about 25° below Mars. Its rings currently tilt towards us which increases its brilliance as seen from Earth. (Magnitude +0.5)

Venus- Venus returns to view this month in the morning sky. Look for its brilliant beacon in the same area of the southeastern sky where Mars and Saturn rose earlier. It rises shortly before morning twilight begins to brighten the eastern sky. (Magnitude -4.6)

Note: Apparent magnitude values range from -4 to +6 for most planets and visible stars. The lower the value the brighter the object. A decrease of 1.0 magnitude is 2.5 times brighter.

Hold the star chart high above your head and match the compass directions to the direction you are facing. Adjust the star chart by orienting Ursa Major (Big Dipper) to match its position in the sky.

The star chart approximates the sky from astronomical twilight to midnight. As the night and month progresses, the constellations shift toward the northwest. The celestial equator is measured in hours (h). The ecliptic is measured in degrees.