What does all this sighting information mean?
Time is when the sighting opportunity will begin in our local time zone. Note that all sightings will occur within a few hours before or after sunrise or sunset. This is the optimum viewing period as the sun reflects off the space station and contrasts against the darker sky.
Visible is the maximum time period the space station is visible before crossing back below the horizon.
Max Height is measured in degrees (also known as elevation). It represents the height of the space station from the horizon in the night sky. The horizon is at zero degrees, and directly overhead is ninety degrees. If you hold your fist at arm’s length and place your fist resting on the horizon, the top will be about 10 degrees.
Appears is the location in the sky where the station will be visible first. This value, like maximum height, also is measured in degrees from the horizon. The letters represent compass directions — N is north, WNW is west by northwest, and so on.
Disappears represents where in the night sky the International Space Station will leave your field of view.
How to Spot the ISS – What to Look For
Look for a very bright ‘star’ or point of light moving very quickly across the sky. It will be moving faster than a commercial jetliner. The space station has no strobe lights and it does not produce a contrail. There is no noise and it does not ‘twinkle’ or blink.
Light from the station is reflected light from the sun. The station presents a fairly large point of light – much bigger and brighter than any star or planet. And, unlike a star or planet, it travels across the sky.
For the best results, observers should look in the direction shown at the time listed. Although bright passes can often be spotted in our local towns and villages, if you can get away from city lights it will be easier to see. Because of the speed of an orbiting vehicle (see below), telescopes are not practical. However, a good pair of field binoculars may reveal some detail of the structural shape of the spacecraft.
How high is the ISS and how fast is it moving?
The International Space Station travels in orbit around Earth at a speed of 17,500 miles per hour (that’s about 5 miles per second!). This means that the Space Station orbits Earth (and sees a sunrise) once every 92 minutes! On average, the ISS orbits at about 220 miles above the Earth.