Though the International Space Station orbits Earth 16 times a day, sightings don’t always align with clear skies here in the Pacific Northwest. But this weekend, stargazers will have nine chances to see the third brightest object in space.

After two passes over the Northwest on Friday, one at 9:34 p.m. and another at 11:09 p.m., the space station will be visible five times on Saturday and another four times on Sunday. On Saturday, the space station will pass over Seattle at: 12:46 a.m., 2:23 a.m., 4 a.m., 10:22 p.m. and 11:59 p.m. On Sunday, the times will be: 1:36 a.m., 3:13 a.m., 9:34 p.m. and 11:11 p.m. (To see the full listings and sign up for alerts, go to

The space station looks like an airplane or a very bright star moving across the sky. It does not have flashing lights or change directions, and it will be moving considerably faster than a plane, according to NASA.

Though it makes 16 orbits around Earth each day, the space station is only visible within a few hours of sunset or sunrise, because it isn’t bright enough to be visible in daylight.

It may not be a welcome sight to those concerned about light pollution, however. According to a recent study accepted by the Monthly Notices of the Royal Astronomical Society, manmade space objects have lightened the skies by up to 10 percent.

This exceeds the threshold astronomers set for light pollution over 40 years ago, according to the space sector publication SpaceRef.

“Unlike ground-based light pollution, this kind of artificial light in the night sky can be seen across a large part of the Earth’s surface,” John Barentine, director of Public Policy for the International Dark-Sky Association and co-author of the study told SpaceRef. “Astronomers build observatories far from city lights to seek dark skies, but this form of light pollution has a much larger geographical reach.”