Not only was it the year Neil Armstrong landed on the moon, Woodstock changed the concept of the music festival forever, and colour TV launched in the UK - 1969 was also the year that Sesame Street launched, 40 years ago today.

As commemorated by a Google doodles on the logo of the search giant in the US this week, Big Bird and his cohort of puppet compatriots have been delighting children in America and around the world for four decades with their kooky combination of literacy and numeracy-based features and simple storytelling. Today's image depicts Sesame Street roommates Bert and Ernie.

It's occasional guest stars (including, recently, David Beckham and Ricky Gervais) have been a boon to the show's popularity, with such distinguished political figures as Kofi Annan and famous musicians like Tony Bennett and Little Richard all dropping in to help out at various points in the show's history. With the first episode of the 40th series, in which First Lady Michelle Obama will join familiar faces like Elmo, Kermit, Bert and Ernie, scheduled for 10 November, the celebrations are due to roll on for the next week in honour of one of the world's most enduring childhood favourites.