SpaceX Falcon 9 launch paints glowing 'jellyfish' across Western US skies (photos, video)

Parts of the Western United States were treated to a cosmic spectacle Sunday evening, as a giant streak illuminated the skies from Los Angeles to Phoenix.

Minutes after SpaceX's Sept. 28 Starlink launch lifted off from Vandenberg Space Force Station (VSFS), in California, the Falcon 9 rocket supporting the mission reached the upper atmosphere to create a phenomenon often referred to as a "jellyfish" effect.

Falcon 9 launched at 11:04 p.m. EDT (7:04 p.m. local PDT; 0204 GMT, Sept. 29). The rocket carried 28 new Starlink satellites to join SpaceX's growing wireless internet megaconstellation of over 8,000 networked spacecraft. The dusk liftoff provided ideal conditions for the setting sun to illuminate Falcon 9's expanding engine exhaust against the darkening sky, as onlookers for hundreds of miles gazed in amazement.

The density of Earth's upper atmosphere causes the exhaust plume of a rocket's engines to expand as it ascends. The launch site at Vandenberg Space Force Base is notorious for its overcast and extremely foggy conditions, but Sunday's clear skies created the ideal conditions for Falcon 9's jellyfish to emerge.

Among the many treated to the skyward spectacle, Space.com's Managing Editor Brett Tingley managed to snap a photo of the phenomenon as the rocket flew over Afton Canyon, in the Mojave Desert.

"I was camping in Afton Canyon in the Mojave National Preserve when I noticed a colorful streak of light in the sky. I've seen plenty of Falcon 9 'jellyfish' online but never in person." Tingley said. "It was lit up gorgeously from below by the setting sun and made for a surprising start to a night of dark sky stargazing."

Posts to X also highlighted the spectacle as it crossed the sky, like these photos and video from West Coast spaceflight photographer, @spacecoastwest:

Sightings were also reported to the American Meteor Society (AMC), which tracks and triangulates anomalies in the sky (usually meteorites) using witness submission data.

Last night's launch prompted seven different fireball reports to the website, with a video from spectators in Phoenix, Arizona, wondering if the long streak moving across the sky might be a comet.

Sunday's launch was the 28th mission for this particular Falcon 9 first stage, which landed downrange on SpaceX's droneship "Of Course I Still Love You," in the Pacific Ocean about 8.5 minutes after liftoff. The rocket's second stage continued to orbit, successfully deploying the satellites into low Earth orbit (LEO).

Sights like last night's aren't super rare, but can sometimes be hard to predict. Launches near dawn and dusk most often create the conditions for the jellyfish phenomenon, so if you live within a few hundred miles of a launchpad, keep your eyes to the skies.