As the New York Post says, "It’s an intergalactic ménage à trois that doesn’t involve Uranus."
NYPost reports are sure stupid, the event takes place in our Solar System - Pftttt.
intergalactic
[ˌin(t)ərɡəˈlaktik]
ADJECTIVE
relating to or situated between two or more galaxies.
“intergalactic gas”