Video shows mystery object blazing a trail across the dark early morning sky.

As usual there is outlandish speculation about an alien visit, but there is genuine puzzlement and disagreement among experts over the mystery object.

Scientist Vladimir Surdin believes 'silver clouds' were the cause of the multi-coloured night sky witnessed by thousands of people.

Like an approaching UFO, the bright white luminous ball glides over a field, before heading into woodland.

No official explanations for darkness over swathes of Yakutia amid conspiracy theories of a UFO, new weapons tests, a meteorite, or pollution from wildfires.

Siberian night sky illuminated by launch from Baikonur in Kazakhstan.

When Vadim Kolpakov went on an expedition to the north of Irkutsk region, he had no inkling of the sensational discovery he was about to make.

Mysterious 'gigantic' hole in remote region spotted by helicopters over gas-rich Yamal peninsula.

Powerful telescope placed 1.3km below the icy water hopes to track invisible particles from the sun and stars.