12 Mar 2012


  • Jupiter and Venus are lining up for the closest point in Earth's sky during their conjunction
  • Conjunctions happen frequently between these two

Our two brightest planets, Venus and Jupiter are drawing closer and closer together in the night sky this week.  This will undoubtedly result in many UFO sighting reports and other questions due to their low proximity to the horizon and appearance there for around two hours.

Monday evening, March 12, they will line up side-by-side in the west, then Tuesday evening, March 13, they will be only 3 degrees apart with Venus just above and to the right of Jupiter.  3 degrees is about the width of two fingers held out at arms length, while the "apparent" width of a full moon is around a half of a degree.  The conjunction will last until around 10:30 p.m. local daylight time.

Venus will be at magnitude -4.3, while Jupiter -2.1.  Lower numbers mean brighter objects with this magnitude scale, which originated in the second century B.C by Greek astronomer Hipparchus.  However, Venus is not 2.2 times brighter than Jupiter in reality.  In 1856, a British astronomer Norman Pogson defined Hipparchus's scale using mathematics in a logarithmic relationship.  Two objects differing by five magnitudes differ in brightness by 100.  So an increase in one magnitude is a brightness scale increase of 2.512.  Hence, for Venus and Jupiter, the 2.2 magnitude difference is a ratio difference of 7.59.  Venus will be nearly eight times brighter than Jupiter.

Many think that such conjunctions between Venus and Jupiter are rare.  They actually occur every 13 months.

Source:  Earthsky.org (image)

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