After the Pluto encounter, Stern asked Brian May, the Queen guitarist and astrophysicist, if he would compose a track to celebrate the Ultima Thule flyby.

“I did scratch my head for a while,” said May. “The name is quite hard to conjure with. But then it came to me that this is about man’s desire to reach out into the universe and explore, and see things that have never been seen before.

The New Horizons track, May’s first solo single for two decades, included a message from Stephen Hawking and was premiered at the control centre shortly before the flyby. “It’s been very exciting. I feel like I’m on that thing,” May said. “To me, it’s about the human spirit and reaching out to discover where we are and why we are here.”

Little is known about Ultima Thule, or 2014 MU69, to use its official name. But based on preliminary observations, scientists think it may resemble a giant peanut with two large lobes fused together. The dark rock may contain frozen carbon monoxide, carbon dioxide, molecular nitrogen and methane, which may be exposed by impact craters on the surface.