Satellites of Jupiter and M - 17

Satellites of Jupiter and M – 17

The four major satellites of Jupiter orbit the giant planet in periods ranging from just under 2 days to 17 days. They can be seen to change position from night to night. Sometimes their motions become evident after only a few minutes’ observation. Only a small telescope is required to detect all four of the satellites and several can frequently be seen in rigidly held binoculars. This table shows the approximate positions of the moons at about 3 a.m. (EDT) on the evenings indicated. First column of numbers identifies the moons and their positions relative to Jupiter’s disk. (1=IO, 2=Europa, 3=Ganymede, 4=Callisto, and 0=Jupiter’s disk.) The third column approximates a telescopic view of the satellites’ positions. The orientation of the satellites is shown inverted as seen in a standard astronomical telescope.

Galaxy M - 17

M17, variously known as the Horseshoe, Swan, Checkmark, or (most often) the Omega nebula, is one of the grandest sights available to telescopic observers in the summer Milky Way. Its brightest, rectangular portion has a mass about 800 times that of our sun, and more than 35 stars are embedded in the nebula. This photo, obtained with a cold camera designed by the photographer, is 1 17.5 minute exposer on High Speed Ektrachrome, through a 12.5 inch reflector at f/4.5 Photograph by Greg Griffith.

(By James Mullaney and Henry J. Phillips, Astronomy, August 1976)

August Satellite Jupiter. August Satellites of Jupiter 3:00 a.m. EDT. 12:00 p.m. PDT