A few weeks ago we had a couple of nights in which the International Space Station (ISS) made some evening twilight transits that were visible across northern Arizona. The first night the ISS transited from the northwest across the sky to the east. As it swung across the evening sky it passed near Mizar in Ursa Major then near Polaris in Ursa Minor. The following night it traveled from west to southeast and passed near the Moon and Jupiter before it entered into the Earth’s shadow.
Both of these final images are composites. Each was shot with a 16mm ultra-wide angle lens at f/4.0, ISO 800, and 10s exposure. For the photograph above, 16 images were composited. For the photograph below, seven images were used. In Photoshop, images are assembled as layers then blended using Lighten mode. This allows the streak of light from the ISS to show through all layers. The advantage to this method — compared to a single image of longer duration — is that the sky does not become overexposed. Instead the result is a dark background upon which the ISS flies.
Both images were taken at the Kachina Wetlands located a few miles to the south of Flagstaff, Arizona. This location provides wide open skies for viewing objects low on the horizon and offers ponds of water that produce wonderful reflections of the stars.
To find out when the ISS will fly across your area, visit either of these sites: