Several political and economic unions have been formed between countries during the past decades.
The geographic coordinate system enables every location on the Earth to be exactly specified.
This animation presents some interesting facts in the field of astronomy.
This animation demonstrates the states and largest cities of the USA.
Mercury is innermost and smallest planet of the Solar System.
The Earth is composed of several spherical layers.
Domesticated animals and crops originate from various parts of the world.
Uranus is the 7th planet from the Sun, a gas giant.