A mysterious streak of light in the night sky baffled many Europeans on Christmas Eve, with speculation running wild as to whether it was a meteor, a comet or space junk.

Videos captured in Germany, France and Belgium show the blaze of light passing across the sky more slowly than a typical shooting star, and with greater brightness and detail.

The leading edge of the streak appears round and white, while the tail trailing it has an orange tone in some images.

People commenting on Twitter wondered about a range of possibilities. Some suggested it might be a comet, while others thought it could be space junk.

There was also speculation about rocketry. The last major blast-off, of a Russian Soyuz-2, was Friday, and some amateur astronomers conjectured that a spent rocket stage was plunging back toward Earth.

German and Belgian astronomical authorities differed on the cause.

A spokesperson for the German Aerospace Centre, the country's national aerospace research institute, told a local newspaper that the celestial phenomenon was "99.9 per cent" certainly a meteor.

"Every year 200 tonnes of material falls to Earth. Sometimes it's a big chunk," Andreas Schutz said.

The Royal Observatory of Belgium disagreed, saying Sunday in a statement on its website that the streak of light was from the atmospheric re-entry of the final stage of a Soyuz rocket that launched on Wednesday and delivered three astronauts to the International Space Station two days later.