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Our Friendly Skies - January 2012

December 31, 2011|By ROD MARTIN and ANDY SMETZER
  • January 2012 All-Sky Chart
January 2012 All-Sky Chart

For a more detailed tour of the nighttime sky listen to "Skylights" at antpod.com by Chris Kopco of the Brish Planetarium.

 
There are many bright stars and constellations in the January evening sky.  
 
The bright winter stars are above the southeastern horizon dominating the sky.  The Winter Oval of bright stars is easy to spot extending from near the horizon to near the zenith is visible.  Bright stars in Orion, Canis Major and Minor, Gemini, Auriga, and Taurus marks the oval. Overhead among the stars of Taurus, look for a tiny, teacup shaped group of stars. This is the Pleadies star cluster. Use binoculars to observe this gem ... it is quite beautiful. It is also the logo for Subaru, the Japanese automaker.
 
Look west to see the disappearing great square of Pegasus the Flying Horse.  It appears lower and lower each night.
 
North has the Big Dipper climbing from the horizon with its handle beginning to point more and more toward the horizon.
 
Rising in the east is Leo's backwards question mark promising that spring is on the way.
 
 
Solar System
 
Visible Evening Planets

  • VENUS is bright in the southwest after sunset.
  • JUPITER is high in the south.
Visible Morning Planets
  • MERCURY is visible low in the southeast before sunrise the beginning of the month.
  • MARS is brightening near Leo's tail.
  • SATURN is high in the south at dawn.
 
A highlight in the planets occurs this month on our planet, Earth!  Since Johannes Kepler found that orbits are elliptical instead of circular, there must be a time when the planet is closest to the sun and a time when it is most distant.  We are now in the midst of winter so the Earth must be far away from the sun, right?  WRONG!  Seasons are caused by the directness of the solar radiation.  In winter we are tilted away from the sun so it is colder.  Earth is actually closer to the sun in winter than summer.
 
The point in the orbit that Earth is closest to the sun is the perihelion.  This year we are closest to the sun on Jan. 4 around 7 p.m.  The distance is 91,401,000 miles or 147,096,000 kilometers.  The average is 93,000,000 miles.  We are farther from the sun in July than January.
 
The two brightest planets are visible in the evening sky.  Venus is brighter than anything except the Sun and Moon.  Jupiter is next.
 
Venus glows at -4 magnitude, while Jupiter glows at -2.5.  Each magnitude is about 2.5 times brighter or dimmer (depending on how you are comparing) than the next number.  That means that Venus is about three times brighter than Jupiter.  You will notice that they do not look that different.  Venus is low and close to the horizon so a lot of its light is absorbed and scattered by our atmosphere.  Jupiter is higher so its light is more direct.  Both are impressive.
 
Use binoculars or a small telescope to examine the four larger moons of Jupiter.  They change their positions from night to night.  Galileo used them to help prove the Sun centered model of the solar system.
 
Mars rises during mid evening below Leo the Lion.  It is becoming brighter in our sky because it is actually getting closer to the Earth.  Mars has a larger orbit than the Earth.  According to Kepler, Mars moves more slowly in its orbit than Earth, so every two years Earth passes between Mars and the Sun.  Our planet is now catching up to Mars so it will appear bigger in telescopes and double in brightness.  Look for the reddish-orange "star" toward the east or left of the backwards question mark of the lion.  Mars crosses the constellation border into Virgo this month.
 
Saturn is not very far behind Mars in the constellation Virgo.  It is slightly dimmer than Mars and lacks the color.  Saturn rises around midnight and is highest and easiest to observe just before morning's twilight.
 
The Quadrantid meteor shower peaks during the morning of Jan. 4.  This is often a very intense shower of very short duration.  around 2 to 3 a.m. 60 to 200 meteors per hour are possible.  Look between moonset and morning twilight for the best chance.  The radiant or center of activity is in the area between the Big Dipper and Draco the Dragon's head in the north.  
 
 
Sun and moon
 
You may have noticed an increase in the amount of daylight.  Since the solstice in December the daylight has been increasing as we progress through winter toward spring and summer.  
 
On Jan. 1, sunrise is at 7:32 a.m. and sunset is at 4:56 p.m., for 9 hours and 24 minutes of daylight.  By Jan. 31, sunrise is at 7:20 a.m. and sunset is at 5:28 p.m., for 10 hours and 8 minutes of daylight.  
 
The sun appears to move from Sagittarius into Capricornus on Jan. 20.
 
The moon reaches first quarter on Jan. 1, full on Jan. 9, last quarter on Jan. 16, new on on Jan. 23, and a second first quarter on Jan. 30.
 

Tristate Astronomers
 
The Tristate Astronomers monthly meeting is the third Wednesday of each month.  For information about the program or outreach activities, check the website at www.tristateastronomers.org.  Links to the William Brish Planetarium and antpod are available at the website.

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