Potential explanations have ranged from supernovae to aliens (which, sorry, is extremely unlikely).
Given that there are between 100 and 400 billion stars and at least 100 billion planets in this galaxy, alien life is extremely likely, intelligent life also likely, star-fairing intelligent life also. But not necessarily carbon based or organic.
12 posted on 05/04/2020 2:35:29 PM PDT by PIF
(They came for me and mine ... now its your turn)