Cheetah

Cheetahs (Acinonyx jubatus) are the fastest land mammals on Earth and live in the open grasslands of most parts of sub-Saharan Africa and Iran. They are characterized by a golden fur covered with small, black spots and prey on smaller herbivores such as antelopes and hares. Because of their light and agile build, cheetahs are able to accelerate from 0 km/h to 100 km/h in 3 seconds and run at incredible speeds of up to 120 km/h over short distances. Chasing prey costs massive amounts of energy and requires so much of their bodies that cheetahs even risk brain damage at the end of a chase. As a result, they have to rest and recover in the shadow after each endeavor, during which they are mostly unable to defend themselves or their prey against other predators. Male cheetahs are often social and may live in groups to establish a territory and even hunt together, but female cheetahs are mostly solitary and hunt alone. Females raise their cubs on their own and leave them behind once the young become independent of their mother. Subsequently, female cubs leave the litter as well, but male cubs may remain together for the rest of their lives.


Information sources: National Geographic, WWF

Image: Cheetah in the savanna grasslands of Serengeti National Park, Tanzania. Credit: Tobias, Wikimedia Commons.

The Moon

The Moon is the celestial body that orbits the Earth. It has a mean radius of ~ 1737 km, a mean distance to Earth of ~ 385 thousand km and an orbital period of ~ 27.3 days. Earth’s satellite is thought to have formed approximately 4.5 billion years ago as a result of the impact between the proto-Earth and a celestial body called Theia, not long after the formation of the Solar System. The Moon has a differentiated structure and consists of a crust, mantle and core and its surface is scarred with many impact craters.


Information source: NASA

Image: Full Moon as seen from Earth. Credit: Gregory H. Revera, Wikimedia Commons.

Earth

Earth is the largest terrestrial planet in the Solar System, the third planet from the Sun and the only astronomical object known to sustain life. It has a mean radius of ~ 6371 km, a mean distance to the Sun of ~ 150 million km and an orbital period of ~ 365 days. Earth is thought to have formed approximately 4.55 billion years ago and has one natural satellite, the Moon. The planet has a differentiated structure consisting of a crust, mantle and core and features plate tectonics. Importantly, Earth harbors abundant liquid water at its surface, most of which can be found in its oceans. The planet is surrounded by an atmosphere that contains ~ 78 % nitrogen (N2), ~ 21 % oxygen (O2) and several other trace gases, including carbon dioxide (CO2) and water vapor (H2O).


Information source: NASA

Image: Earth as seen from space, also known as the Blue Marble. Credit: NASA/NOAA/Reto Stöckli.

Pillars of Creation

The Pillars of Creation are pillars of interstellar gas and dust in the Eagle Nebula, ~ 5 lightyears tall and at a distance of ~ 7000 lightyears from the Earth. Massive new stars are being formed within the pillars, but at the same time the gas and dust are being eroded by the intense ultraviolet light from nearby young stars. The different colors in the Pillars of Creation result from the electromagnetic emission from different elements: blue is related to oxygen, orange is related to sulfur and green is related to both hydrogen and nitrogen.


Information source: NASA

Image: The Pillars of Creation in the Eagle Nebula as seen from the Hubble Space Telescope. Source: NASA/ESA/Hubble Heritage Team.

African Lion

African lions (Panthera leo) are apex predators that live in the barren savanna grasslands of most parts of sub-Saharan Africa, blending in well with the surroundings because of their golden fur. They feed on large herbivores such as wildebeest, zebras, buffalo, warthogs and gazelles, as well as smaller rodents. Lions are the only cats that live together in groups, called prides, which may consist of up to three males, ten lionesses and their young. They rest for most of the day, but are generally active at dusk and during the night. Male lions are known for their long manes and defend the territory of the pride against rivals, while the lionesses are the main hunters and stalk their prey in groups before closing in for a kill. As they grow, young males leave the pride to establish their own, while females often stay behind. Historically, the lion has been regarded as the king of beasts and is therefore still used as a symbol of courage, strength and royalty.


Information sources: National Geographic, WWF

Image: African lions feeding on a buffalo carcass in Kruger National Park, South Africa. Source: Luca Galuzzi, Wikimedia Commons.

Tropical Cyclone

Tropical cyclones are massive storm systems that may generate strong winds and heavy rain, as well as high waves, storm surges and even tornadoes. They are characterized by a low-pressure center, called the eye, around which thunderstorms rotate rapidly and spiral outward. Tropical cyclones originate over warm oceans and seas, where the evaporation of large amounts of water creates a vast energy source for storms. Colossal rain clouds form as the hot, moist air rises up in the atmosphere, cools and becomes saturated with water, while the strong rotating winds result from the conservation of angular momentum as the air flows towards the eye of the storm. Together, these processes result in an intense atmospheric circulation system that may continue to grow in size and strength under the right conditions. Tropical cyclones may also be classified as hurricanes or typhoons, depending on their strength and location.


Information source: Encyclopaedia Brittannica, Wikipedia

Image: Cyclone Catarina above the South Atlantic as seen from ISS on March 26, 2004. Credit: NASA.

Emperor Penguin

Emperor penguins (Aptenodytes forsteri) are the largest of all penguins and are adapted to the extreme cold of the ice sheets of Antarctica and the surrounding seas. They are characterized by a black head and backside, with a hint of yellow on their breast and behind their ears. Because of their streamlined bodies and strong flippers, emperor penguins are excellent swimmers, and at sea they can dive to a depth of more than 500 meters, deeper than any other bird. As carnivores, emperor penguins prey on fish, squid and krill, while they are hunted by leopard seals and killer whales as well as large seabirds, which scavenge mainly on chicks. They are very social animals that huddle together in large colonies in order to survive the harsh conditions of their icy environment. Emperor penguins breed in winter and while females go hunting in the Antarctic waters for themselves and their unborn chicks, males keep the eggs warm in brood pouches on top of their feet. Male and female emperor penguins stay together during the full breeding season, but some are even rumored to remain faithful to their partners for life. After an egg hatches, the parents of the newly born chick take turns foraging at sea and raising their chick in the colony.


Information source: National Geographic, WWF

Image: Emperor penguin family on ice along the Weddell Sea, Antarctica. Source: Christopher Michel, Wikimedia Commons.

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