One poster on Reddit claimed the source of the black ring was smoke from a Supercross event at Lumen Field. Video showed black smoke Saturday emitting from a pyrotechnics display.

Many locals speculated that the ring could be a rare weather phenomenon, a swarm of insects, or even an extraterrestrial sighting.

Another image showed the circle hovering near Seattle's iconic Space Needle. Lumen Field posted a similar clip on their Instagram page showing the same smoke rising into the sky. 'Let the smoke rise.

A strange phenomenon appeared on the Seattle skyline Sunday, when a mysterious black ring hovered over Lumen Field and ...

The skies above Seattle have been busy with lots of bald eagles as spring approaches. Some are locals getting their nests ready for eggs — and defending those nests from migratory birds passing ...