A fireball that brightened the Tokyo sky early Thursday was likely to have been a small meteor, a space science expert said.

The meteor, believed to have been somewhat less than 1 meter in diameter, moved from southwest to northeast in the sky above the Japanese capital while emitting a blaze of light comparable to the shine of a full moon, and may have broken into pieces later, said Shinsuke Abe, an associate professor at Nihon University.

Supplied photo taken from footage captured by Daichi Fujii of Hiratsuka City Museum shows a fireball crossing the sky as seen from Hiratsuka, Kanagawa Prefecture, on July 2, 2020. (Kyodo)

Some pebbles that were not burned up could have reached the ground, he added.

Social media came alive early Thursday morning with many people saying they heard a loud bang, with some mistakenly attributing the sound to upstairs neighbors.

Many people who were awake at the time also witnessed the sky suddenly lighting up.

Around 100 meteors with 1-meter diameters fall into the atmosphere every year, with relatively smaller ones like the fireball observed Thursday being an even more frequent occurrence.