He is, of course, primarily known as a comedian, but Dara Ó Briain is also something of a maths and science buff.

He studied maths and theoretical physics at university. He’s met Stephen Hawking, he’s made science programmes with Professor Brian Cox. He’s quite clever, don’t you know. And now he’s written an astronomy-focused book for children, called Beyond the Sky: You and the Universe. Dara joined Ray D’Arcy in studio, and Ray started by quoting Dara from another interview, in which he said that if he saw an adult reading his new book, he’d give them a stern look.

Ray protested that Dara’s book is a kind of revision notes for parents who weren’t paying attention in science class. But there are lots of grown-up books parents can check if their children have questions, Dara told him:

"There are plenty of books from which you can do that, but they don’t have cartoons in them."

Ray wondered if Dara – who has a nine-year-old child – had ever tried to explain the concept of infinity to his child. For instance, when you tell your child that you love them to infinity and they reply by saying that they love you to infinity plus one, Ray says has to tell his child that you can’t have infinity plus one. Having lightly scolded Ray for ruining a lovely moment between parent and child, Dara then goes on to explain that there are many infinities:

"There’s an infinity of infinities…. between any two numbers, you’ll fit an infinity."

Are our heads designed to cope with the vastness of the universe, the infinities of infinities? Ray wondered. It’s something that we’re not very good at, Dara conceded. And it gets worse (or better, depending on your point of view) when it comes to the vastness of the universe, he told Ray that:

"You have to look at the universe as a four-dimensional thing, that is, space and time together."

And we’re not really programmed to do that very well, if at all, are we? We can see three dimensions, but not four (indeed, if we cover one eye, we can see two dimensions). Gravity affects time. And if you want to find out more, pick up Dara’s book (if he’s not watching) or any reputable science explainer.

"The number one expectation people should have for me at some point I should crack a funny. That’s the gig."

Dara’s day job is being a comedian, which makes him, he tells Ray, feel slightly awkward with the whole book for kids thing, as everyone who knows of him, expects him to be funny. But he’ll be happy if people – especially children – get what they want from his book, even if it mightn’t leave them in stitches.

Beyond the Sky: You and the Universe by Dara Ó Briain is published by Scholastic.

You can hear the full chat with Dara, as well as the rest of The Ray D’Arcy Show here.