How Close is Close?

   There has been a lot of discussion about what the Grand Conjunction between Jupiter and Saturn will look like to the unaided eye. The separation will be as close as 1/5th the width of the full Moon, which is hard to visualize. Astronomically, using angular angle measurements of degrees, minutes, and seconds, the separation will be 10.0′ (10 minutes). The full Moon, for comparison, is approximately 0.50o , or one-half of a degree.

   Still hard to visualize? Hold a quarter or a nickel at arms length and look at the edge of the coin. The width of the coin’s edge at arm’s length is approximately the separation between Jupiter and Saturn on the 21st.

   Still trying to visualize the 0.10′ separation? From whenever the old days were, there was a test of visual acuity (eyesight!) that involved being able to see the double star in the bend of the handle of the Big Dipper. There are actually 3 stars there but Mizar and Alcor are the two that are more easily seen. So, if you are able to see Mizar and Alcor then you should be able to see the separation between Jupiter and Saturn.


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