Skygazers in Hanoi, Vietnam on the night of May 19 were treated to a strange, rapturous sight.
A broad, vertical column of light appeared in the sky.
Images of the column circulated on Vietnam's National Centre for Hydro-Meteorological Forecasting Facebook page on May 19, at 1:21 am:
Photo from Trung tâm Dự báo khí tượng thủy văn quốc gia/Facebook
Another photo posted to the same account shows the beam of light from the point of view from a street:
Photo from Trung tâm Dự báo khí tượng thủy văn quốc gia/Facebook
The above photo was likely pulled from a video that was posted in the comments:
GIF from Trung tâm Dự báo khí tượng thủy văn quốc gia/Facebook
Some commentators on a Reddit thread, where the Facebook video circulated, noted that the mysterious sky phenomenon resembles images from the popular video game franchise, "Halo".
Caused by lights from a building
The comments on the post by the National Centre for Hydro-Meteorological Forecasting suggest that the phenomenon might have been man-made.
The organisation commented on the post that the lights were definitely not some kind of "barrier gate to travel through space" but the result of "bank lights".
Corroborating this, one Nghiêm Thanh Huyền posted a photo in the comments that shows a building casting the vertical column of light:
Photo from Nghiêm Thanh Huyền/Facebook
A quick search on Google Maps reveals that this photo was likely taken from across Hoàn Kiếm Lake.
The building in question appears to be the State Securities Commission of Vietnam.
Top photo from Trung tâm Dự báo khí tượng thủy văn quốc gia/Facebook