The focusing muscles of the eyes move around 100,000 times a day. To give your leg muscles the same workout, you would need to walk 80km (50 miles) every day.
21
Mars had an oxygen-rich atmosphere around 4 billion years ago
13
Scientists at the Zhejiang University in China have developed an ultra-light material known as carbon aerogel.
3
Your thumb is about the same size as your nose.
124
An unprotected human can survive up to 1.5 minutes in space with no permanent bodily damage.
82