If you miss this one, you'll need to hang around until 2080 for another chance.
Jupiter and Saturn are moving so close to each other in our sky that they will appear to form a "double planet." University of Texas at Dallas Associate Professor Mary Urquhart says the extremely rare phenomenon will be visible for the next few nights for 1 to 2 hours after sunset, with optimal viewing on Mon., Dec. 21, which is the Winter Solstice.
Dr. Urquhart said a conjunction like this was last seen clearly from Earth in March 1226. A similar occurrence was recorded in 1623, but the sun hindered the view on that occasion.
To see the conjunction, Dr. Urquhart recommends looking into the western sky a couple hours after sunset. The two very bright lights will be Jupiter and Saturn, with the crescent moon also visible in that portion of the sky.
Earthlings won't have to wait as long for the next chance to see a mashup between the two planets. Dr. Urquhart said it will happen again on March 15, 2080. She talked with KRLD's Chris Sommer.