Sometimes I’m not sure what planet my young son is on

‘MERKERY!’ my son shouted, sticking his hands in the air for emphasis. ‘Well done!’ cried his teacher with polite surprise, as I’d just asked him to tell her which planet was closest to the sun. He likes to be quizzed on planets, because they’re some of his favourite giant objects, and I like quizzing him about them in public because it makes him look like a toddler genius, earning me vicarious praise.

His fascination with planets came about accidentally, since we use a picture of Earth from space to show him that Ireland and England are separate countries. We do that because he’s an English person and we don’t think it’s ever too early for them to learn this, and also because he often demands to see his grandparents at a moment’s notice, and we want to explain why he can’t. ‘This is Earth,’ we say patiently, ‘and this is England, and this is Ireland, where Nana, Grandad and Granda live.’ From this, he’s developed a fascination with planets and he now loves both dinosaurs and their natural enemies (giant space rocks), particularly the eight planets in our solar system.

And therein lies the rub. Eight. Eight planets. Teaching him about space has meant my wife and I have, for the first time, had to grapple with a different reality than the one we were taught, requiring us to ignore Pluto, cast out of the planetary roll call in 2006. We were aware of this, but it didn’t seem real until we started reading him books where Pluto is not mentioned, like an auntie you used to see all the time but who hasn’t been spoken of since she left your uncle for that judo instructor.

For my dad, the same thing happened with long division. An engineer by trade, he learned long division in 50s Northern Ireland, which meant reading from textbooks that appeared to have been recovered from 19th-century whaling boats. All I wanted was for him to help me divide one big number by another big number, preferably using the methods written in large, colourful text in my primary school textbooks. My dad seemed to think I should be learning the methods taught by alchemists to the children of Egyptian kings. He couldn’t understand why someone had changed the rules, especially since he used hard maths every day and no one had thought to tell him. I laughed at the time – or rather I would have laughed, if I hadn’t been too busy helping him construct a rudimentary abacus from some chicken bones – but, looking back, I have sympathy for his position, and his desire for his own educational legacy to be passed from father to son.

Back at nursery, my son hit gold with the second planet (‘Veemus!’) and again with the largest (‘Judiper!’), but drew a blank when asked what planet we were standing on. ‘ERFF!’ cried his little friend Ivor, after a slight pause. ‘Ah, ERFF,’ my boy repeated, ‘that’s where Nana, Grandad and Granda live.’ Long division or not, my father’s legacy is secure.