The ozone layer averages about 3 millimeters (1/8 inch) thick.
The sun is 330,330 times larger than the earth.
The deepest point in the sea: the Mariana Trench off Guam in the Pacific Ocean; it is 10,9 km (6.77 miles) below sea level.
The tallest waterfalls in the world are Angel Falls in Venezuela. At 979 m (3,212 ft), they are 19 times taller than the Niagara Falls, or 3 times taller than the Empire State Building.
The order of the planets, starting closest to the sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
In ancient China, the nose of a criminal who attacked travellers was cut off.
There are more than 16,400 parking metres in Manhatten, New York.
The first motorcycle speedway race was held in Maitland, Australia, in 1925.
Traffic lights were used before the advent of the motorcar.
The fewest aeroplane passengers killed in one year was 1 in 1993 and the most was 583 in 1977 when two Boeing 747s collided on the runway at Los Rodeos airport, Tenerife, the Canary Islands.
The first written account of the Loch Ness Monster, or Nessie, was made in 565AD.
Beer was the first trademarked product – British beer Bass Pale Ale received its trademark in 1876.
In 1963 the French launched a cat called Feliette into space.
Julius Caesar was the first to encode communications, using what has become known as the Caesar Cipher.
The 16th century Escorial palace of King Phillip II of Spain had 1,200 doors.