A fantastic amount of talking. The militaries would want to be in readiness, for example, just in case the extraterrestrials are not friendly, and the diplomatic corps would be doing their best to figure out how to communicate with them.

A lot of religions might also be thrown a bit into the air by the arrival of aliens, so there would be some chatter there, too.

Are aliens subject to human rights? Are they beings also made in God’s image, etc.