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Around 4:35 a.m., residents in localities like Quang Ngai and Da Nang reported seeing a leaf-shaped streak of light slowly drifting from north to south before fading after several minutes. Photos and videos of the strange sight quickly spread across social media.
"I thought it was a plane at first since there’s Chu Lai Airport nearby," said Nguyen Viet Hiep, a resident of Quang Ngai. "But after checking online, I realized it could be from a Chinese rocket."
In Da Nang, Huynh Van Muoi, 58, said the light looked like a giant kite floating in the sky. "At first we thought it was just morning sunlight," he recalled. "But when it lasted nearly 10 minutes, we knew it wasn’t natural."
A leaf-shaped cloud of light is spotted in the skies over central Vietnam. Video obtained by VnExpress
Vietnam’s National Center for Hydro-Meteorological Forecasting later said the glowing trail was likely caused by China’s Tianzhou-9 cargo spacecraft, launched from Hainan’s Wenchang Space Center around 4:34 a.m. Vietnam time. The spacecraft was carried into orbit by a Long March 7 rocket.
According to experts, the light was created by rocket exhaust illuminated by sunlight high in the atmosphere. As the rocket passed through the stratosphere, engine exhaust, including water vapor, propellant gases and chemicals, reflected sunlight, creating the glowing cloud seen from the ground.
Dr. Nguyen Ngoc Huy explained that the Long March 7 rocket travels at hypersonic speeds, generating shockwaves that lower air pressure and temperature. This causes water vapor in the air to condense, forming the distinctive cone-shaped white cloud trailing the rocket. Known as a vapor cone, this cloud is often mistaken for smoke but is actually just condensed moisture.
The phenomenon is more visible in humid conditions and usually fades quickly as the rocket passes through different air layers.
According to China's Xinhua News Agency, Tianzhou-9 separated from the rocket around 10 minutes after launch and entered orbit successfully. The spacecraft is carrying supplies, fuel and equipment to resupply China's space station.
This was China's fourth cargo resupply mission and the 584th launch in the Long March rocket series.
