Early risers across the Southeast looked up Tuesday morning, Oct. 13, and saw a glowing, bell-shaped cloud drifting across a still-dark sky. It was not a comet or a malfunction. It was the sunlit exhaust plume of a SpaceX Falcon 9 rocket carrying cargo to the International Space Station, a twilight effect skywatchers call a space jellyfish.

The rocket lifted off from Space Launch Complex 40 at Cape Canaveral Space Force Station in Florida at 6:35 a.m. EDT on SpaceX's 35th commercial resupply mission for NASA, known as CRS-35. Because the station's orbit sent the rocket north along the U.S. East Coast, the display was visible far from Florida, with viewers reporting it from Georgia and North Carolina, according to Space.com.

For millions of people who will never see a launch in person, these dawn and dusk displays are the closest look they get, and they can be startling. Knowing what causes them helps viewers tell a routine launch from an emergency.

Sunlight Above, Darkness Below

The effect depends on timing. Near sunrise or sunset, the ground is still in shadow, but the rocket climbs high enough to catch direct sunlight. As Falcon 9 rises into thinner, less dense air, its exhaust plume spreads out far wider than the rocket itself, and that expanding cloud of gas lights up against the dark sky.

NASA's Kennedy Space Center explained the sight in a post on X after the launch. A jellyfish happens near sunrise or sunset when "the exhaust plume from the rocket becomes brightly illuminated, creating a glowing shape resembling a jellyfish," the center wrote.

Cold temperatures at altitude add to the effect. As the rocket climbs, water vapor in the exhaust can freeze into ice crystals that trail behind it and catch the light, Space.com noted in explaining a similar plume after a July 9 Starlink launch.

The phenomenon is not new — the trajectory is what matters. Launches that head northeast along the coast, like this one, carry the plume into view of large population centers. An Aug. 25 Starlink launch from Florida produced a jellyfish photographed over lower Manhattan from Hoboken, New Jersey, according to Space.com.

From Colbert to Durham, Viewers Compare Notes

In Colbert, Georgia, northeast of Atlanta, Ellen Alence told Space.com she was surprised to see the rocket when she opened her back door to let her dogs out, and photographed it over her farm.

Farther north in Durham, North Carolina, Richard Mack Wilson-Leigh caught the flight seconds before stage separation, about 2.5 minutes after liftoff. Right after separation, the first-stage booster fired its engines to turn around for a landing back at Cape Canaveral, adding a second burst of light to the sky.

"At first, I thought it was a comet," Wilson-Leigh said. He told Space.com his mind swung between finding the sight beautiful and wondering whether something had gone badly wrong, and he joked that the booster burn briefly made him think the rocket had blown up.

That reaction is common, and it is why official sources matter. Launch providers, NASA and the U.S. Space Force publish schedules in advance, and a glowing, expanding cloud that appears minutes after a scheduled Florida launch is almost always the rocket. Viewers who see something they cannot explain should check those sources first rather than relying on social-media guesses.

A Cargo Run Behind the Light Show

The mission itself was routine. Falcon 9's second stage carried a cargo version of SpaceX's Dragon capsule into orbit with about 6,300 pounds (2,860 kilograms) of supplies and research equipment for the station.

The load includes the last set of International Space Station Roll-Out Solar Arrays, which will boost the station's power supply. NASA officials said Dragon "will deliver hardware to manufacture artificial retinas in microgravity," along with 3D heart tissue models, brain organoids for neurodegenerative disease research, and materials for studying how a new type of glass forms in weightlessness, Space.com reported.

Dragon is scheduled to dock autonomously to the space-facing port of the station's Harmony module at about 11 a.m. EDT Thursday, Oct. 15. NASA's coverage plan lists live arrival coverage, which Space.com said begins at 9:15 a.m. EDT. The capsule will stay about a month before returning experiments to Earth with a parachute splashdown in the Pacific Ocean off California.

Catching the Next Twilight Launch

For people hoping to see a jellyfish themselves, the best odds come with launches scheduled roughly within an hour of sunrise or sunset that fly northeast from Florida's Space Coast. Clear skies matter more than distance, and a low, unobstructed view toward the south or southeast helps viewers up the coast.

There is no need for special equipment, and officials have not flagged any hazard from Tuesday's display. The glowing plume is high in the upper atmosphere, far above clouds and aircraft — it simply drifts and fades over several minutes as the sunlight angle changes.

Readers should still treat any unusual sky event with common sense. A sudden flash or loud boom near a launch or landing zone may be a planned sonic boom from a returning booster, which launch providers typically announce in advance for nearby counties. When in doubt, check NASA, SpaceX, or local emergency-management channels.

The bottom line: Tuesday's glowing cloud over Georgia and the Carolinas was a scheduled cargo launch catching the first light of dawn. The Dragon capsule's arrival at the space station Thursday morning is the next milestone to watch.

What Readers Want to Know

What was the glowing cloud seen on Oct. 13?

It was the exhaust plume of a SpaceX Falcon 9 rocket that launched SpaceX's CRS-35 cargo mission from Cape Canaveral, Florida, at 6:35 a.m. EDT, lit by sunlight high in the atmosphere.

Where was it visible?

Viewers reported it from Georgia and North Carolina, among other places, because the rocket flew north along the East Coast toward the space station's orbit.

Why does it look like a jellyfish?

The plume spreads out widely in the thin upper atmosphere, and near sunrise or sunset it catches sunlight while the ground below is still dark, creating a glowing, bell-shaped cloud.

Was it dangerous?

No. The plume was high in the upper atmosphere. Officials have not reported any hazard, and the launch was successful.

How can I see the next one?

Watch for launches from Florida scheduled near sunrise or sunset, especially those flying northeast along the coast, and check NASA and SpaceX launch schedules for times.

When does the cargo arrive at the space station?

Dragon is scheduled to dock at about 11 a.m. EDT on Thursday, Oct. 15.