Summer Solstice Space Station

We’re currently enjoying a series of nightly (and often twice or thrice nightly) passes of the International Space Station, coinciding with the bright nights of summer solstice.

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I took this shot on the night of solstice, June 21, 2011, as the Space Station came directly overhead, flying out of the west then heading off into the east. So we’re looking a little west of north here, toward the bright northern horizon. Pity some light cloud hazed up the sky. The pass began at 11:12 pm so the sky was still quite bright, though even an hour or two later at this time of year the northern horizon is tinged with perpetual twilight glow, at least at my latitude of 51° N.

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To create the image I took a series of 100 3-second exposures (as long as the bright sky would allow) taken 1 second apart in rapid-fire fashion with the camera firing automatically with a remote timer. The 1 second gap between exposures creates the gaps in the Space Station trail.

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I processed the images in Adobe Camera Raw, and exported them all as TIFFs to their own folder. I then used Chris Schur’s excellent “Star Trails” Photoshop Action to stack all those images into one composite image showing the complete flight of the Space Station across the sky. A little application of Shadows and Highlights helped bring out the foreground and bright sky detail.

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I used the Sigma 8mm fisheye lens and Canon 5D Mk II to capture the whole sky, for a still and time-lapse sequence suitable for projection in a full-dome video planetarium … because the neat thing about this method is that the same set of images can be strung together sequentially (using Photoshop Extended’s Movie function) into a time-lapse movie of the pass, showing cloud and star motion as well as the ISS passage. The same techniques work for star trails, as indeed you can see here with the stars of the northern sky (Big Dipper at left and Cassiopeia at right) trailing around the North Star.

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