There is zero gravity at the centre of earth.
Oceanography, the study of oceans, is a mixture of biology, physics, geology and chemistry.
Earth orbits the sun at an average speed of 29.79 km/s (18.51 miles/sec), or about 107 000 km/h (about 67,000 miles/hour).
Earth is the densest planet in the solar system and the only one not named after a god.
the deepest mine in the world is Western Deep Levels near Charletonville, South Africa. It is 4,2km (2.6 miles) deep.
The US has one of the highest fire death rates in the industrialised world, with more than 2 million fires reported each year.
Air becomes liquid at about minus 190 degrees Celsius.
Water expands by about 9% as it freezes.
The typical bolt of lightning heats the atmosphere to 50,000 degrees Fahrenheit.
Sound travels through water 3 times faster than through air.
The word “biology” was coined in 1805 by Jean-Baptiste Lamarck.