On Friday, January 6^th, the outer giant planet Jupiter reaches the point in its orbit around the Sun that places the Earth in between Jupiter and the Sun. This is known as opposition, and opposition is an orbital position that applies to solar system objects (outer planets, dwarf planets, asteroids, comets, etc.) orbiting the Sun beyond the Earth’s orbit. An object at opposition will have approximately the same heliocentric longitude as the Earth’s heliocentric longitude – on Friday both planets will have a heliocentric longitude of about 137^o.
   For those keeping track, last year Jupiter was at opposition on January 5^th. An opposition of Jupiter occurs approximately every 13 months because both Earth and Jupiter are moving. After one Earth Revolution, an Earth year, the planet Earth will be where it was the previous year, at opposition with Jupiter. However Jupiter will not be there because it has moved during the past year as well. It will take the Earth that extra month or so to catch up with Jupiter. Earth moves 360^o each year while Jupiter moves approximately 12^o each Earth year.

   When an object is at opposition it rises at approximately the same time as local sunset and that same object at opposition sets at approximately the time of local sunrise. In other words an object at opposition will be up all night from sunrise to sunset.
   Picture our Moon at full phase and how it is directly opposite the Sun, with the Earth in between. The full Moon in effect is at opposition but we call it the full Moon instead. And like Jupiter at opposition, a full Moon rises at sunset, sets at sunrise and is visible all night. February’s full Moon, by the way, was on the 3^rd.

   
Take a brief tour of the Jovian (Jupiter) system. Music by Dark Matter.
Live recording of music written by Richard Johnson. Video by me!

   
   
   
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   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.