It's not the building that's 100, nor the collection inside, but the museum's name and identity. For it was on June 26th 1909 that the "Science Museum" formally split itself off from the V&A across the road. Originally the South Kensington Museum, this repository started off as a museum of the industrial and decorative arts, funded from the success of 1851's nearby Great Exhibition. The steady accumulation of apparatus and instruments during the 19th century created a growing technological nucleus, until eventually the separation of the artistic and scientific collections became necessary. And it's the centenary of that divide which is being celebrated today.
If you've not been down to the Science Museum since you were a kid, you may not have realised that it's changed. If you have offspring of your own, however, you're probably more than familiar with the place. The heart of the collection's still reassuringly familiar, but there's now a lot more now to appeal to a younger more interactive generation. Oh yes, the Science Museum is a sprightly centenarian, and no mistake.
Once you've got past the two shops near the entrance, most people start by exploring the Making the Modern World gallery. This is a timeline of world-changing artefacts extending the length of the ground floor (with a darkroom of space artefacts positioned anachronistically along the way). Ten exhibits have recently been picked out as special Centenary icons, and these are marked by a special plaque on the floor alongside. You're invited to stand in awe in front of each amazing object in turn, and then vote for which of the ten you believe to be the most groundbreaking afterwards.
First up is the steam engine, invented two centuries before this museum was born, and then the rather younger V2 rocket, whose engine transformed the way we think about warcraft and propulsion. A few of the ten are included because of what they represent, not because the example on show is anything particularly special. An electric telegraph, a Model T Ford, a model of the DNA double helix. But a few are the breathtaking genuine article. That's Stephenson's Rocket, the first proper steam locomotive, so close that you can almost touch it (please don't). The specks in that tiny brass case are mouldy samples used by Alexander Fleming to isolate penicillin in the 1930s. And that squat cone-shaped metal box at the far end of the gallery, the one with the seriouslyburnt bottom - that's been round the Moon, that has. It's the actual Apollo 10capsule, part of a dress rehearsal for the lunar landings 40 years ago, and here it is for you to view in deepest Kensington. What's not to love?
Keep going and you'll reach the newest part of the museum, the high and airy Wellcome Wing. There are some push-button futuristic screen bits on the upper floors, but this extension's really about making money. Buy your tickets for the IMAX 3D cinema here ('U' certificate only), or maybe stop off to purchase the results of an experiment involving coffee beans, lactose and boiling water. Just don't go looking for the excellent Launchpad in the basement - they've moved the hands-on physics extravaganza up to the third floor. Note to interested adults: you'll have more fun (and get fewer funny looks) if you take an eight-year-old with you.
But you'll find the genuine Science Museum tucked away on some of the other floors, away from the major attractions. Many of these areas haven't been upgraded in years, and visiting cub scout groups show their displeasure by nipping hurriedly through the heritage displays in seconds. The Mathematics section, for example, still looks as if a bunch of 1950s geometry teachers made some 3D shapes out of coloured card and then bunged in a few slide rules and pairs of compasses for good measure. The Computing area, once cutting edge, is now lodged firmly in a historical era of cogs, valves and chip-fitted Sinclair calculators. And the Maritime galleries contain an unfeasibly large collection of diving helmets, oil-rig drill-bits and propeller shafts. The number of model ships gathered here verges on the obsessive, and on entering yet another aisle to see yet another British Empire steamboat in a glass case it's easy to imagine that you're still seeing the museum as it was 100 years ago.
If you've not been back to the Science Museum lately, maybe this weekend would be a good choice. Three days of special centenary events kick off today and run through until Sunday, and will no doubt attract large crowds. Alternatively, why not wait and sneak in midweek before the school summer holidays begin. Then maybe you can go stand on the flat-packed plastic suspension bridge without being knocked over, or go play on the pulleys in the Launchpad when nobody's looking, or just go and admire the very finest technological exhibits laid out in all their glory. The Science Museum is for kids, but it's not just for kids. And 100 years on, its history is still the future.