Jupiter and the Galilean Moons from a Sidewalk

Jupiter and the Galilean Moons, 7:28 PM EDT, 2 January 2013as seen from 40 McKay Road, Dundas, Ontario, CanadaLeft to right: HD27742 (star), Ganymede,Europa, Io, Jupiter, HD27639 (star), Callisto. Best image of moons and of Jupiter combined.

Jupiter and the Galilean Moons photographed 7:28 PM EDT, 2 January 2013 from a sidewalk in Dundas, Ontario. Left to right: Ganymede, Europa, Io, Jupiter, HD27639 (a reddish star), and Callisto. This is a montage of the best frame of the moons and the best frame of Jupiter, shot at different exposures because of the great difference in brightness between the two. Details follow below.

In my post on 1 January I described “first light” through an old 80mm f/15 refractor telescope: the first pictures I thought were fairly good after repairs, which happened to be of the photosphere of the sun. Although the nights this winter have been disappointingly cloudy in southern Ontario so far, on the evening of 2 January 2013 we had a cold, occasionally clear night. Between some of the clouds I was able to set up the 80 mm again and get some nice views of Jupiter and the Galilean moons, and also take some photos. This time I went out to the sidewalk in front of my place, with two of the legs of my tripod in the snow.

The results were very encouraging given the circumstances. Two major cloud bands on Jupiter were clearly visible, as were the four Galilean moons. With my Nikon D5100 body shooting at ISO 1250 at prime focus, I exposed for the moons at 1/8th of a second, and for Jupiter at 1/125th, taking multiple frames of each.

After getting inside and warming up, and following a little adjustment for contrast, brightness and sharpness, I was able to over-lay the best image of Jupiter onto its overexposed self on the best image of the moons. The result is the montage above.

There are much more sophisticated ways of taking images of Jupiter, the moon, and the other planets these days, even with a simple telescope such as I used. It was nice to see at least a recognizable image of the disk of Jupiter with the approach I used for this one. The D5100 is a nice dSLR for this kind of application because the LCD screen on the back swivels around. It was possible to get a pretty good view of the Jovian system using live view on the camera.

Chart of Jupiter and the Galilean Moons

The expected arrangement of Jupiter and the four Galilean Moons at 6:30 PM EST 2 January 2013 as portrayed by the free planetarium software Cartes du Ciel.

I had confirmed the positions of the moons, and also the small reddish star HD27639, with the free planetarium software Cartes du Ciel, before heading out, and so had a pretty good idea of what to expect in terms of positions. What made the experience really nice tonight was that I was joined on the sidewalk by some of my neighbours, who were very excited by a peek at old Jove. They enjoyed looking both with an eyepiece on the ‘scope and also on the camera live view screen.

Sharing these experiences, even as simple as this one was, is very rewarding. Many local astronomy clubs offer “sidewalk astronomy” experiences, too.  If you have a telescope and know how to find a few things in the sky, get out and share it with your neighbours, friends and family. If you don’t have a telescope and would like to find out more, seek out local clubs and see what they have to offer.

As a memento I made a print of the photo for my neighbours… they don’t have a computer, so email wasn’t an option. That’s OK – when Galileo was looking at the same scene four hundred years ago this month, he didn’t have email either.

© 2012, David Allan Galbraith
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