The best way to give Mark a pained expression, and to have him change subject, is two say two words. “Tabby’s Star”. Or, to be more specific, KIC 8462852.

For a non-scientist like me, those two words are the most exciting thing to happen in astronomy for a hundred years. Tabby’s Star is the oddest thing in the whole universe. Dozens, hundreds, of speculative theories about aliens, alien civilisations, and alien technology can be constructed.

For science-types like Mark, that speculative explosion is enough to drive him up the wall. “There’s no evidence for alien superstructures. Grow up.” Yes, Tabby’s Star is the star that a year ago gave headlines in many newspapers and magazines. With those exact words “Alien superstructures”.

A year later, it’s in the news again because Tabby’s Star is still behaving in ways that nobody can explain, and therefore people like Mark have to suffer people like me who have overactive imaginations. But then, then, there’s a gleam in his eyes and for a moment he’s there with me on the wild ride that this star is.

Because whether he’s right or not, that Tabby’s Star’s behaviour is natural and explainable, it’s doing some really strange things. Like dimming rapidly – twenty per cent between 2011 and 2013. Something the size of 20 Jupiters would explain that dimming, but there’s nothing around the star that exerts that gravity pull on the star.

To Mark, it’s important to find out what is going on, and that’s not helped by my wild speculations. To me, what’s important is to imagine the possibilities.The journey there is the important bit. For Mark, it’s the destination that is important. When the humdrum and mundane solution is found, my fun ends. Understanding the star is Mark’s fun. It will be one more notch in the long list of things he wants to know.

My speculative extravaganza is much improved when he drops his resistances, and join me in thinking about the impossible potentials of it. When his brain isn’t dictating reality to him, his eyes shine and become huge. He’s beautiful when he lets go of his logical anchors, and my imagination improves ten-fold when it gets a little help from him.