It can grow to around

It can grow to around 30 metres in length. It has a heart the size of a small car, and yet, its brain is only about three times the size of yours (assuming you're human). It can eat about 500kg of krill every single day. Its young doubles in length (from 6 metres to 12 metres) and triples in weight (from 3 tonnes to 9 tonnes) in the first six months of its life. It is the biggest animal that has ever lived on this planet. It is the blue whale.

I'd probably heard most of those facts. I'd seen many pictures, moving and still, of blue whales in my time, and I probably thought I knew that a blue whale is very, very big; but I didn't - not really. I went to the Natural History Museum in London on Saturday. They have a life-size model of a blue whale in one of the galleries. It takes your breath away. Like everything else in the museum, it's a bit scuffed around the edges and could do with a lick of paint, or at least with being dusted every so often, but it is still an incredible thing to see.

They also have a large collection of meteroites. One of them, an iron one, is about the size of two large sacks of potatoes. It sits on display in the middle of the room and you are encouraged to touch it. It's a strange experience to run your hands over something that has travelled through space - it's impossible to imagine how far it travelled to get to earth.

On Monday, I touched some more weird things. First, I encountered an animal that looked like an elephant-pig on stilts. Apparently, it was a tapir. It let me stroke the top of its head, and then it shut its eyes with delight when I tickled behind its ears. Ten minutes later, I was getting the same reaction from this 3 tonne white rhino.

The name 'White' Rhino is a corruption of the Afrikaans word 'weit', which means 'wide', a reference to its wide mouth.

So far, being 29 has been very educational.