When SpaceX launched a rocket carrying an Argentine Earth-observation satellite from California’s central coast, both the night sky and social media lit up.
People as far away as San Francisco, Sacramento, Phoenix and Nevada, posted photos of the Falcon 9 rocket’s launch and return on Sunday night (local time).
It was the first time SpaceX landed a first-stage booster back at its launch site at Vandenberg Air Force Base, about 210 kilometres north-west of Los Angeles.
The Air Force warned residents they might see multiple engine burns by the first stage and hear one or more sonic booms as it returned.
Previous SpaceX launches have triggered similar confusion, with December’s launch causing motorists to stop their cars and Twitter to light up.
But many far beyond the region were taken by surprise when the launch illuminated the sky, wondering what the otherworldly looking sight was. Some speculated it was a comet or an alien aircraft.
“Something exploded in the sky west of Phoenix,” Laura Gadbery wrote on Twitter. “Anyone catch it or know what it was?”