International Space Station

Visual Brightness

The ISS appears brightest when passing overhead becoming the third brightest "star" in the night sky. It dims slightly with decreasing altitude over horizon.

Orbit

The ISS travels around Earth every some 90 minutes which equals to 16 orbits or 16 sunrises and sunsets onboard each day. Observed from ground, the ISS looks like a fast-moving star traveling 27,600 kilometers an hour. Unlike airplanes, it does not have flashing lights or change direction.

Days in orbit: 9,291

Ground Track

Earth rotates about 15° per hour or 360° in 24 hours for which reason the ground track appears shifted westwards by approx. 23° every orbital period of 1.5 hours. The orbit of the ISS is nearly circular and when projected on a Google Mercator world map its trajectory draws a near-sine-wave shaped ground track.

Visibility

The International Space Station orbits with an inclination of 51.6°. This means that it will never cross 51.6° northern or southern latitudes. The ISS will never pass directly over head for observers beyond ±51.6° latitude, in places such as Alaska and Scandinavia or the southern tip of Chile or New Zealand's Campbell Island.