It most certainly wasn't space as in the lot of them hanging out amongst the stars, but it was a different planet. It had to be, considering Sirius didn't recognize anything and it was safe to say that he knew more about secret civilizations than most.
"Phwoar!" His exclamation needed no real words for his excitement, frankly. He tugged at Gwen's elbow to get her to come with and moved to stand next to Miles, head tilting back to look up at the tall buildings, and watch the flying car-things zoom by.
"Brilliant," he declared. It was all very impressive, and very large, from the looks of it. "What do you both think we ought to do first? Get one of those flying cars?"