A bright flare lit up the sky late on 19 April over Kiev and its surrounding neighborhoods. Local media caught the mysterious luminous object on video, and minutes later an air raid alert sounded in the region.
You can also watch the video of the bright flash over Kiev on our Odysee channel.
Sputnik examines what we know about the flash so far:
Air Defense Theory
Reports of a bright flash in the sky over Kiev appeared on Wednesday at around 22:00 local time (19:00 GMT). Shortly after, an air raid siren sounded in the city.
The head of the office of Ukraine's President Volodymyr Zelensky, Andriy Yermak, went on social media to say that the glow had been caused by the Ukrainian air defense as part of Russia's ongoing special military operation in Ukraine.
"Don't worry about UFOs. It's our air defense," he is cited as having written in a message that was deleted shortly afterwards.
Defunct NASA Satellite
On the other hand, the head of Kiev's city military administration, General Serhiy Popko, was convinced that the intriguing flash which had lit up the sky all around Kiev had resulted from a NASA space satellite crashing to Earth.
"Around 22:00 on 19 April, a bright glow from an airborne object was observed in the sky over Kiev. According to preliminary information, this phenomenon was the result of a NASA space satellite falling to Earth. To avoid casualties from falling debris, an air raid alert was announced. Air defense systems were not operating at the time," Popko wrote.
The Ukrainian Air Force attributed the glow in the sky to the "fall of a satellite/meteorite" and emphasized that "at present there is no threat of the enemy launching an air attack" in the direction of Kiev.
A day before the incident, the National Aeronautics and Space Administration (NASA) had issued a warning that its old satellite - the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) - was set to fall to Earth after spending more than 20 years in orbit. The decommissioned scientific device had been launched back in 2002 to study solar flares and coronal mass ejections from the sun.
However, after the theories had been advanced linking NASA’s satellite with the bright flash in the skies above Kiev, Rob Margetta, NASA's public affairs officer, told Sputnik that the agency’s RHESSI satellite remains in orbit.
"We are tracking a NASA satellite called RHESSI that is expected to re-enter Earth’s orbit tonight. However, that satellite remains in orbit at this time. NASA and the Department of Defense continue to track RHESSI. No other NASA satellite re-entered the atmosphere earlier today", Margetta said.
A Meteor?
A Ukrainian educational project dedicated to space, The Alpha Centauri, was cited in media reports as speculating that the flash or fireball over Kiev could have been a bright meteor. The project rejected the NASA satellite theory saying that Kiev and its environs were not in the path of RHESSI's orbit at the time.
The Ukrainian National Space Facilities Control and Test Center said that at 21:57 it had registered a "high-energy acoustic event".
“The estimated location of the epicenter of the explosion is in the Kiev region. The event is probably associated with the entry of a cosmic body into the dense layers of the atmosphere," the center said. It added that the information would be further assessed.
UFO?
Of course, the mysterious celestial phenomenon prompted numerous jokes and memes on Ukraine's social media networks, with many speculating that the flash must have been an unidentified flying object (UFO).