February 2012 Skywatching


 

Orion, winter’s flagship constellation, is in the southern skies during the evening hours of February.  The pattern is easily found by locating three stars of nearly equal brightness and equal spacing about halfway up in the southern skies.  This represents Orion’s belt.   The reddish star Betelgeuse can be found above the belt stars and bluish Rigel below.  The two stars are display contrasts of star color.  Compare the two stars’ colors through binoculars.  The colors indicate temperatures.  Rigel is much hotter than Betelgeuse.  In addition, Betelgeuse is very large.  The sun and  inner solar system could fit inside an empty Betelgeuse.
 
While you have your binoculars, look for the Great Orion Nebula among the stars of Orion’s sword.  The nebula has a distinct, greenish glow.  The fantastic colors in photographs do not appear to the human eye.   Film and electronic photography have the ability to collect light over long time periods where the colors are revealed.
 
During February, we experience about 1 hour of additional sunlight in the Chicago area.  By month’s end the sun sets around 5:40 p.m. and rises around 6:30 a.m.  This year we add a day to the calendar to account for the earth’s revolution around the sun.  To keep our calendar matched with the seasons, we add a day.  If we do not reset the calendar every four years, eventually the coldest days of the year would occur when the calendar reads July.  See the US Naval Observatory for a longer description.
 
Moon Phases
Full — February 7
Last — February 14
New — February 21
First — February 29

As the sky darkens during early February 2012,  two bright planets dominate  the sky.  Venus shines brightly in the western sky, standing above the horizon and Jupiter gleams from the southern skies.  Early in the month, the moon is east of the planets and outside the view shown above.

At night only the moon outshines Venus in brilliance. In turn Venus easily outshines Jupiter, appearing about 6 times brighter than the solar system’s largest planet.  Venus is our planet’s nearest neighbor and its clouds are highly reflective as they return over 70% of the sunlight that reaches them.

Jupiter takes nearly 12 years to orbit the sun once.  As we revolve around the sun each year, stars appear in the morning sky just before sunrise.  Each day they rise earlier than the previous day.  Each week they appear farther toward the west at the same time.  This westward movement of the stars reflects our revolution to the east in our planet’s orbit.  Because Jupiter revolves so slowly, its location in the sky reflects the westward movement of the stars in general, with some differences.

Several weeks after appearing in the morning sky, the stars and Jupiter appear in the east around sunset.  Looking each week at the same time, we notice that the stars are higher in the east.  Several weeks later, the stars are in the south at sunset, continuing to appear farther west at the same time.  As Earth revolves, the stars appear in the west as the sky darkens, and then reappear in the eastern sky just before sunrise, repeating this annual cycle. 

As this westward match continues, watch Jupiter during February approach Venus.  Late in the month, the moon passes in the region of Venus and Jupiter as indicated on the chart above, February 24-27.

As an extra, with binoculars or at low power in small telescope, look for the planet Uranus near Venus on February 9.  With optical aid, Uranus will display a bluish-green disk while the stars will appear as points.  The chart above shows a magnified view of the area around Venus.  Uranus is just at the limit of human eyesight in a dark sky, so some magnification through a binocular or small telescope will be needed.

With binoculars on February 22, look for Mercury and the moon low in the west at 5:45 p.m.  Locate a view spotting with a good view of the natural horizon, away from houses and trees.

Mars shines brightly from the eastern evening skies during the month near Denebola, the star that represents Leo’s tail, although it is one-third the brightness of Jupiter and only about one-tenth the brightness of Venus.  During the month Mars will increase in brightness as our planet approaches and passes the Red Planet.  On the evening of February 9, the moon appears nearby.

A few nights later, the Moon appears near the star Spica and Saturn with constellation Corvus nearby.  The chart above shows the view at 1 a.m.  As the night progresses, the moon and other objects will appear to rise, appearing in the southern skies around sunrise.

The chart above shows the positions of the planets in the solar system at mid-month.  With the planets moving in a counter clockwise motion, Earth is catching up and readying to pass Mars.  Venus moves faster than Earth and it is slowly catching up with our planet.

Take a look at the sky this month!

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