Some stargazers in Washington state wondered if they’d spotted a UFO on Tuesday as a trail of lights moved across the night sky.

But the actual source was more terrestrial: Earlier in the day, SpaceX had launched a fresh batch of Starlink satellites in the opposite corner of the country at the Kennedy Space Center in Florida. As NBC affiliate station KING5 reports, even slight reflections from the sun were enough to make those 60 satellites light up in a chain pattern.

Starlink, which launched in beta last year, uses low-orbit satellites to deliver high-speed internet across the entire United States. While the service is on the pricey side at $99 per month—plus $499 up front for receiver hardware—it’s a potential boon to rural customers who might otherwise have no high-speed options.

SpaceX founder Elon Musk said on Wednesday that Starlink has received 500,000 preorders to date, and while he claimed that the service should have no technical problems meeting demand for those users, it clearly needs to launch more satellites to keep up. Astronomer Jonathan McDowell has counted nearly 1,500 Starlink satellites in orbit today.

Using satellites to deliver faster internet isn’t without downsides, though. One astronomer told KING5 that reflections from the satellites can interfere with research by space observatories. That concern echoes a story last week by Vox’s Brian Resnick, which noted that the satellites can block telescopes’ view of the night sky and introduce a glow that makes stars harder to see.

SpaceX has made several changes to its satellites to reduce their brightness, such as installing sun shades similar to those on car windshields, but the light pollution issue still persists. With more low-orbit internet satellites coming from OneWeb and Amazon, the decline of truly dark skies may be as inevitable as the uptick in mock-UFO sightings.