He was taking the piss, and they fell for it (and some people watching fell for it too!).
He is very dry and that's just his humour. Initially what he was trying to say that the HEAT is different in the UK to the US. EG. I find UK sun much more unbearable than Italy for example even if they are the same heat and same degrees. He then just went along with having more than 1 sun as the girls were saying "omg, no there isn't" even entertaining the fact there is more than a sun
He was right about the moon though,