On the night of May 17, people across the United States were stunned to see a glowing white streak moving across the sky. The unusual sight appeared around midnight and was seen even in states as far south as New Mexico. At first, many believed they were witnessing a rare natural event. But scientists have now confirmed the actual reason behind this stunning light show—and it wasn’t natural at all.
People Thought It Was a Space Weather Event
When the streak appeared, many skywatchers assumed it was a phenomenon known as STEVE. STEVE, short for “Strong Thermal Emission Velocity Enhancement,” looks like a ribbon of white or mauve light and often appears during strong space weather events. It’s different from the more common northern lights, though both happen due to particles interacting with Earth’s magnetic field.
That night, Earth was indeed facing a moderate geomagnetic storm (G2 class), caused by a burst of solar material that unexpectedly brushed past our planet. This event led many to believe the glowing streak was STEVE. Even photographers posted images on social media, claiming to have captured the rare event.
But Scientists Found a Different Cause
However, it didn’t take long for experts to figure out that this wasn’t STEVE. According to astronomer Dr. Jonathan McDowell, the real cause was a rocket dumping fuel high above Earth.
A few hours before the light appeared, a Chinese company called LandSpace Technology had launched a rocket named Zhuque-2E Y2 from northwest China. This rocket uses a special fuel called Methalox, which is a mix of methane and liquid oxygen.
How Rocket Fuel Created the Glow
After the rocket reached space, its second stage released leftover fuel while passing over the US at about 250 km (155 miles) altitude. This area is part of the ionosphere, a layer filled with charged particles.
When the Methalox fuel entered this region, it reacted with the plasma in the ionosphere and created a glowing cloud, which people on Earth saw as a bright streak in the night sky.
Not the First Time Fuel Dumping Has Lit Up the Sky
This isn’t the first time a rocket fuel dump has caused such a spectacle. SpaceX’s Falcon 9 rockets also create amazing sky patterns during their fuel dumps. However, those usually form spiral shapes. What made this one different was its straight-line shape and the fact that it was visible at midnight, when such reflections are rare.
Why Methalox Is Gaining Attention
Methalox fuel is becoming more popular in space missions for several reasons. It’s cheaper and more environmentally friendly than other fuels. It also has potential for future Mars missions, as methane and oxygen might be produced on Mars itself. This would allow astronauts to make fuel there instead of carrying it from Earth.
LandSpace Technology became the first company to successfully launch a Methalox rocket in 2023, and this May 17 launch was its fifth mission using the upgraded Zhuque-2 model.
Why It Wasn’t a Reflection Event
Normally, glowing clouds caused by fuel dumps happen just after sunset or just before sunrise, when frozen fuel particles can reflect sunlight. But this event occurred around midnight, which ruled out that possibility.
Instead, scientists believe the light was a result of chemical reactions. When the carbon, hydrogen, and oxygen from the Methalox fuel entered the ionosphere, they reacted with its particles and created a visible glow. A 2021 study from the US Naval Research Laboratory also found that such reactions can create long-lasting light visible from the ground and space.