After a long drought of planets in the evening, mighty Jupiter is finally up for viewing this month. It offers plenty to see with both binoculars and telescopes of all sizes, and is a welcomed sight to skywatchers. All five major planets were visible in the evening sky last summer (a true planetary bonanza!), but one-by-one they set and moved into the predawn morning sky. An exception is dim remote Mars, which still lingers in the western sky and sets shortly after the Sun.
Jupiter comes to “opposition” to the Sun on June 10th, which means that it rises as our Daytime Star sets and is visible all night. This lovely planet has been described as a “four ring circus” due to its four bright Galilean satellites (those discovered by Galileo with his primitive telescope) continuously dancing around it from night to night. Binoculars 35mm to 50mm in size at magnifications of 7x to 10x will show them, depending on where they are in their orbits. Larger glasses—and especially image-stabilized ones, which wonderfully eliminate the “shakes”—make them definite at powers of 12x to 16x and reveal Jupiter’s disk.
To really enjoy the “circus” a telescope is needed. The smallest of glasses, even a 2-inch at 25x to 30x, lets you watch the moons going through their various antics. The most striking of these are the eclipses where a satellite disappears into Jupiter’s huge shadow and then some time later reappears. Others involve a moon going behind the planet (an “occultation”) or crossing in front of it (a “transit”)—and in this case casting its shadow onto the planet below. The times of these events are given monthly in Sky & Telescope magazine (skyandtelescope.com). To witness these events ticking off right on schedule across the vastness of interplanetary space is a thrill to be experienced!
The rotation of the planet and its cloud bands become obvious at magnifications of around 100x or more, as well as the Great Red Spot floating in its atmosphere when on the side of Jupiter that is facing us. The detail in scopes 6-inches and larger in aperture at 150x or more is truly amazing! All in all, Jupiter is the most active and fascinating of all the planets. If you’ve never seen it in a telescope before, be prepared to be wowed! I will never forget my first view of it at the age of eight, which launched me on my lifelong adventure as an amateur and professional astronomer—and my ongoing mission as a “celestial evangelist.”
As a preview of what’s to come as far as planets go, Saturn rises in the east two hours after Jupiter in June. This ringed wonder is the iconic image of astronomy and space. But it is no match for the endless activity of mighty Jupiter and its moons!
— James Mullaney
Former assistant editor at Sky & Telescope magazine and author of 10 books on
stargazing. His latest, Celebrating the Universe!, is available from HayHouse.com.