Mercury at Eastern Elongation

orbital-positions    On Monday February 10th Mercury, the innermost planet, will reach its orbital position known as greatest eastern elongation. At that moment Mercury, the Sun, and the Earth, would be arranged in something close to approximating a right angle as this graphic shows.
   From our perspective the orbits of Mercury and Venus appear to move from one side of the Sun to the other – from superior conjunction, behind the Sun, out to the left (east) from the Sun to eastern elongation, then reverse and move westward through (inferior conjunction) between the Earth and the Sun to western elongation. From there the inner planet moves eastward going behind the Sun (superior conjunction) and eventually reappearing on the eastern side of the Sun for an eastern elongation. Repeat over and over – do not stop!

   The planet Mercury is currently over the western horizon at sunset local time and will remain visible for most of the month.

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.


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Jupiter at Quadrature ——— Venus at Elongation

   Thursday January 12th the gas giant planet Jupiter reaches the point along its orbit around the Sun where Jupiter would be described as being at western quadrature. It is at a 90o angle relative to the Earth and the Sun.
   Also on this day the inner planet Venus reaches a point in its orbit known as eastern elongation. This puts Venus at somewhere around a 90o angle relative to the Earth and the Sun when viewed looking down from above the solar system but Venus is on the other side of the Sun from where Uranus is currently located.
   In terms of elongation Venus is 47.2o to the east of the Sun. In terms of viewing angle you are the point of a triangle with Venus at the left base corner and the Sun at the right base corner. The angle between the Sun and Venus is the elongation angle, and at 47.2o Venus sets around 3 hours after sunset as its seting motion or speed is (15o per hour based on Earth rotation rate.
   Where is Jupiter currently? Jupiter rises around midnight local time and is located high above the southern horizon at sunrise local time near the blue-white star Spica in Virgo the Harvest Maiden.
   And Venus? Can’t miss this planet as it is the brighest stellar object over the western horizon at sunset.
   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.