I'm not saying it's space whales . . . but it's space whales.
I hope not, whales will not hesitate to demolish threats with sound weapons. Maybe they are scanning for that asteroid thing shaped as a sardine. Is either that or a space dog barking and chasing a space stick. Fetch me that blue ball, good boy.
I hope someone is checking the hum for encoded information.
Cosmology is so interesting in that everything is inferred so indirectly.