Jupiter and Neptune

For the next few months Jupiter and Neptune will be quite close. The dance begins on May 14th with the separation just under one degree, about the low power view of many amateur telescopes. Closest approach will be on May 27, when Neptune will be only 23.5 arcminutes north of Jupiter, after which the gap will widen again.

Oddly enough the gap will again close after June 15th. This is because Jupiter begins to move in retrograde, the giant planet will reverse course among the stars and again pass Neptune in the sky. The second approach will not be quite as close, Jupiter will only approach within 34 arcminutes on July 9th.

By July 21st the gap will have widened beyond 1°, but there is one more movement to this dance. As retrograde ends Jupiter will again reverse course and make one last pass by Neptune in late December, passing within 32 arcminutes of each other on December 21st.

For those that have never seen Neptune in a telescope before, the presence of Jupiter close by is a sign post allowing easy location of the distant gas giant. Neptune is small, only two arcseconds across, a blue-green orb that requires higher magnifications to view properly. Stepping the magnification above 150x or 200x allows this world to be seen as an orb, not simply a star like pinpoint.

All of these passes will see Neptune north of Jupiter by about half a degree. Simply aim your telescope at the bright disk of Jupiter and jump one eyepiece field north to find distant Neptune. The outer gas giant should be the brightest thing above Jupiter.