TAWBAS star party

Editor’s Report: Planet Fest 2015

Venus and Jupiter brightened our spring sky, with Saturn remaining for summer.


If you are reading this before July 1, mark your calendar as a reminder to be outside and looking west for the planetary conjunction of the year. Venus and Jupiter, the two brightest planets, will be strikingly close together in the evening sky at dusk on both June 30 and July 1. Because these two neighbour worlds are brighter than any stars, this is a rare head-turning celestial event.

Of course, Venus and Jupiter have been in the evening sky for months. Venus is the nearest planet to Earth and, consequently, appears to move more rapidly in its orbit than does more distant Jupiter. So from our point of view on Earth, Venus is passing Jupiter. Only rarely is planetary orbital motion as obvious as in late June and early July this year. Back in late May and early June, Toronto-based amateur astronomer Jim Chung was busy imaging Venus and Jupiter, as well as Saturn later in the night. He reports that the images shown below were “taken with my 18-inch ultralight homebuilt Dobsonian Newtonian [Steve Swayze optics] on a motorized base.”

SpringTrinity by Jim Chung

From his front lawn in Toronto, Jim Chung used an 18-inch Newtonian for these portraits of the three planets in our sky this spring. An ultraviolet filter added colour and detail to the Venus image.

The images were obtained at approximately f/20 with a Point Grey Research Grasshopper Express CCD running at 30 frames per second. The advantage of such rapid image acquisition is that split seconds of superb steadiness in the Earth’s atmosphere are captured, then set aside. Only the “good seeing” images are digitally stacked for the final results seen here. Therefore, these portraits of the planets match those cherished moments of perfect seeing that planetary observers talk about at star parties.

Notice the disc of Io in front of Jupiter, for instance, as well as the intricate cloud detail on the giant planet. For 150 years, visual observers have reported telescopic fine detail as seen here, but it has been unpredict­able and only momentary. Now 21st-century backyard astronomers (front yard, too, in this case) can record it for the rest of us to enjoy.

Jim Chung’s Saturn image was taken this spring, so it shows the giant ringed world exactly as it will be seen this summer in your telescope. This reminds me of my very first look at Saturn, in 1958, through my 60mm refractor. That was two Saturn orbits ago, and the planet was in the constel­lation Scorpius, close to where we see it this year. That look was unforgettable: the planet with its rings appearing as a perfect miniature of the pictures in my astronomy books. Of all the sights in astronomy, this is the one to share. From city or country sites, Saturn can be enjoyed in its full glory. Share it if you can, because very few people ever forget the experience.

Editor Terence Dickinson invites your comments and astronomy-related observations and photos, which can be directed to him at [email protected].

Check out the July/August issue of SkyNews (on newsstands now) for an expanded version of Terence Dickinson’s Editor’s Report.

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