The Weekend's Viewing: Orbit: Earth's Extraordinary Journey, Sun, BBC2 The Secrets of Everything, Sun, BBC3

The Fast Show predicted the current state of BBC popular science nearly 20 years ago with a sketch that featured an excitable young man with a Northern accent striding through a landscape while enthusing ceaselessly about everything he could see around him.

He usually wore a woolly hat and an anorak, which meant that the chillier passages of Orbit: Earth's Extraordinary Journey bore an uncanny resemblance to his guileless celebrations of everything under the Sun. The one big difference is an expansion in the vocabulary. Where The Fast Show character pretty much restricted himself to the word "brilliant", the joint presenters of Orbit – Kate Humble and Helen Czerski – have a whole thesaurus of laudatory adjectives at their disposal. In last night's programme, I noted "magical", "extraordinary", "astonishing", "remarkable" and "spectacular", more often than not accompanied by the word "most".

Well, the world can be an impressive place, particularly if you head off to the remoter parts of it, such as Tierra del Fuego or Yellowknife in Canada (characteristically introduced to us as "the coldest city in North America"). But even so, the enthusiasm can get a little wearing. "Join us on the most remarkable journey of your life!" said Kate at the beginning of last night's episode. "Oh, for goodness' sake, calm down, Kate, and just give me the facts," I thought. "You're the one on the limitless travel budget. I'm sitting on a frankly unremarkable sofa watching you spend it. Now get on with telling me why they have glaciers in summer in Chile."

The facts, when they do come, are mostly about weather – the essential idea of Orbit being to profile our annual circumnavigation of the Sun and detail the quirks of meteorology that result from planetary tilt and elliptical swoop. And, though you'll occasionally encounter a word like "perihelion" or "equinox", the facts are delivered to you in a manner that doesn't rise much above primary school level. "Water is transforming from liquid to solid," someone explained at one point, parsing the mysterious appearance of snow. Quite why they need two presenters, I'm not sure – unless all the parachuting, scuba-diving and snowmobile-riding that science presentation now involves proved beyond a single woman – but it adds an air of sweepstake to the thing, and neither has the edge on the other when it comes to verbal bedazzlement. Brilliant, I suppose, anything less being unthinkable.

If Orbit is a bit advanced for you, you can always turn to The Secrets of Everything instead, a zippy, popular science series on BBC3. This features Greg Foot, who presents his essential credentials at the top of the programme by showing us pictures of him when he was five: "I was the kid trawling through the rock pools and the one who tried to turn his bike into a plane," he says. Don't get over-excited about that title by the way, because the stock in trade of The Secrets of Everything are the kind of questions that get asked by curious six-year-olds, including, in last night's episode, "Can a loud noise kill me?" and "Could you survive an unfair fight?" In pursuit of the last mystery, Greg went to Liverpool and invited a group of cage-fighters to beat him up, an experiment with an unsurprising result, but that nevertheless allowed him to touch on adrenalin and G-force, once he got his breath back.

He also launched a homemade space probe (helium balloon and GoPro camera) to investigate the sky question, though I had the feeling that a curious six-year-old might not have been entirely satisfied with the eventual answer. It's light bouncing off the dust and air molecules, he said. Well, yeah, Greg, but why is it blue? Why not chartreuse or purple? Greg drank his own urine at the end... just to show he could. Now, I dare you, Greg, tackle one of the big ones: bear versus shark – which would win?