Bottlenose dolphins are sea mammals which use ultrasound for orientation.
Lymph vessels carry lymph to the blood vessels, while lymph nodes are integral parts of the immune system.
Human activity increases the greenhouse effect and leads to global warming.
The Troll A is an offshore natural gas platform, the largest offshore platform ever built: it rises about 170 metres above water level, weighs 656,000...
Dry land on the surface of Earth is divided into continents which are separated by oceans.
This animation demonstrates the development of the human embryo and foetus.
Water on Earth is in a continuous state of change. The water cycle includes processes such as evaporation, precipitation, melting and freezing.
Vertical forces can break up layers of rock into fault blocks, which then move vertically along the fracture planes.
Tectonic plates can move in relation to each other.
Lateral compressive forces cause rocks to form folds. This is how fold mountains are formed.
The rise and drop of sea levels caused by the gravitational force of the Moon.
Carbon is bound in organic substances during photosynthesis, while during breathing, it is released into the atmosphere.
Typical settlements of the Norsemen were not only established in Scandinavia, they appeared on distant areas as well.
The theatre that has a distinctive shape and excellent acoustics was situated at the side of the Acropolis in Athens.
The magnificent capital of the Aztec Empire astonished even the Spanish Conquistadors.
Soviet labour camps (Gulags) were located far from inhabited areas.
When the Sun, Earth, and the Moon are arranged in a straight line, the Moon can partially or completely obscure the Sun.
Located in the Grand Mosque of Makkah, the Kaaba shrine is the most sacred site of Islam.
Lunar eclipses occur when the Moon passes through the shadow cone of Earth
The centre of the Indian mausoleum complex is a white marble tomb built by Shah Jahan for his beloved wife.