SKY HAPPENINGS

The Sky for February 2011
By Faylene Roth

DAYLENGTH
The period of daylight lengthens by 62 minutes in February. Civil twilight continues to provide adequate light for outdoor activities an additional 30 minutes. Color and detail fade from the landscape during the next half hour of nautical twilight while planets and stars begin to

appear. The final phase of astronomical twilight is recognized by dark skies overhead and a darkening of the skies above the western horizon. The reverse progression occurs in the eastern sky with sunrise. Actual time of sunrise and sunset depends upon the landscape.

MOON HAPPENINGS
February 2 – New Moon occurs at 7:31pm
February 11 – First Quarter Moon sets after midnight
February 18 – Full Moon occurs at 1:36am
February 24– Last Quarter Moon rises after midnight
(The time of moonrise and moonset assumes a flat horizon. Actual time may vary.)

CHINESE NEW YEARS
The second new moon following the winter solstice determines the date for Chinese New Years. While the new moon occurs on February 2 in Mountain Time Zone, the time zone in China is fifteen hours ahead which pushes the date for this year’s Chinese New Year to February 3.

METEOR ACTIVITY
Fireballs frequently occur along the ecliptic during February. These mega-meteors can be as bright as Jupiter and Venus. Best viewing is after 3:00am.

ASTERISMS
The Hyades and the Pleiades feature prominently in the winter sky. Locate the Hyades by identifying the five stars that form the V of the bull’s head in Taurus. Look 10 degrees (width of your fist at arm’s length) northwest of the Hyades to locate the 6 visible stars of the Pleiades. Although they are easily recognized star patterns, they are not constellations. They are known as asterisms. Asterisms may be a sub-part of a constellation or derived from neighboring constellations. Common asterisms include the Great Square of Pegasus, the Big W of Cassiopeia, the Northern Cross in Cygnus, and the Summer Triangle of Aquila, Cygnus, and Lyra. Most asterisms are composed of stars that appear in the same region of the sky but are not near one another in distance. The Pleiades and the Hyades are unusual because they are star clusters, groups of stars that move together and have a common origin in time and space. The Hyades, 151 light years from Earth, contain several hundred stars. At 625 million years old, these stars are only one-eighth the age of our five billion year old sun. (Aldebaran, the brightest star in Taurus, is not part of the Hyades star cluster.) The Pleiades is 440 light years away with more than 1,000 stars that formed only 100 million years ago.

BUILD A TELESCOPE
Don’t miss this opportunity to build your own Galileo telescope and learn how to use it. The Moab Arts and Recreation Center is offering a class this month called Galileo & His Telescope: 402 Years of Astronomy. Participants will build a working replica of the telescope used by Galileo to discover the moons of Jupiter, then take it home with them. Registration is required by February 3. Cost is $75.00 (scholarships available) which includes the telescope and instruction on telescope design, telescope use, and astronomic ideas from ancient times to modern times. The class is taught by Moab resident Alex Ludwig, founder of Red Rock Astronomers, a local astronomy club. The class meets three times: Thursday, February 10; Tuesday, February 15; and Thursday, February 17. Call the MARC at 259-6272 by February 3 to register or put your name on the waiting list for a second class. All ages are welcome.

Note: Hold your hand at arm’s length to measure apparent distances in the sky. The width of the little finger approximates 1.5 degrees. Middle, ring, and little finger touching represent about 5 degrees. The width of a fist is about 10 degrees. The fist with the thumb extended at a right angle equals 15 degrees. The hand stretched from thumb to little finger approximates 20-25 degrees. The diameter of both the full moon and the sun spans only 0.5 degree. 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 - The bright yellow orb of Jupiter dominates the evening sky. Look for it above the western horizon during the fading light of nautical twilight. Jupiter hovers just below, then moves above, the celestial equator during February. Find it below the long faint arm of Pisces. At the beginning of February it sets by 9:30pm. Each evening it appears lower in the sky and sets before 8:30pm by month’s end. On February 7 Jupiter is less than 7 degrees southwest of the waxing crescent moon. (Magnitude -2.2)

Saturn - Look for Saturn on the eastern horizon in Virgo about one hour after Jupiter sets. By the end of the month it rises soon after 9:00pm. Saturn remains in the sky throughout the night and is low on the western horizon in morning twilight. On February 21 Saturn appears eight degrees north of a waning full moon. The two form an equilateral triangle with Spica (Virgo) which is to the right of Saturn. (Magnitude +0.5)

Venus - On February 28 Venus and a waning crescent moon rise within a few degrees of one another. They appear less than 1.5 degrees apart the following morning. Venus dims slightly over the next few months as it retreats from earth in its orbit around the far side of the sun. The interior planets, Venus and Mercury, pass through phases like the moon. Venus is currently 60 percent illuminated. (Magnitude -4.2)

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.

The Milky Way runs parallel to the north-south meridian between 10pm and 11pm throughout February. The view north looks towards the galaxy’s center. The view south looks towards the outer edge of our galaxy.

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.