Next come the decorations. The tree must have been in space for some time, because its needles have reversed. As one Nasa experiment discovered, pine trees get confused in a zero-gravity environment – and rather than pointing downwards, as is usual, their needles start to angle upwards like hairs on the back of an angry cat. Luckily it doesn"t matter which way up they are, because technically there is no up or down on the ISS anyway.