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The day lasts 24 hours just because people wanted to share it like this. There is nothing in nature about hours, minutes and seconds. This division of time was made by man according to his wish. But there is something in nature that happens in one day. Each time the Earth rotates once about its axis, a certain time passes, which we call a day. Using stars, scientists can accurately measure time. In observatories, a day begins when a star crosses the meridian and lasts until it crosses it again. Since man divided the day into hours, minutes and seconds, we can say exactly how long a day lasts: 23 hours, 56 minutes, and 4.09 seconds. This is called a sidereal day. But since it would be difficult to use sidereal day in practical life, we take the day to last 24 hours, so we add a leap year to correct the difference. Image by Gerd Altmann from Pixabay In the old days, people thought that the day lasted from sunrise to sunset. The duration of the night was not counted. The Greeks...

Mammals (Latin: Mammalia) include humans and all other animals that feed their young with milk. Most mammals are covered with fur and have specialized teeth that help them cut or chew food. Compared to other vertebrates (vertebrates have backbones), mammals have a more well-developed brain than other types of animals. Besides humans, mammals include some of the most famous members of the animal kingdom, such as cats, dogs, elephants, and whales. Mammals breastfeed their young and this is their main feature. Mammalian young are born already formed. Before birth, the young develop in their mother's stomach. It feeds in the uterus via the placenta. The umbilical cord connects it to the placenta through which large blood vessels pass, brings food from the mother, and takes away the waste. The time it takes a young to grow up in a mother's body is called pregnancy and does not last equally for every mammal. When born, the young is a faithful image of his parents. Do mammals hav...

Geysers look a lot like volcanoes. These are springs of hot water that giggle at certain intervals. They are caused by high heat in the Earth's interior. They meet in places where there were volcanoes in the recent past. Water from the surface penetrates the rocks through cracks representing natural gutters; it penetrates deep and begins to heat due to the Earth's internal heat. In the same way, together with steam, water erupts back to the surface and builds a wonderful fountain when leaving the earth. Geysers occur in the form of a long jet of water gushing out of the ground. This movement is constantly renewed. There are geysers in particular in Iceland, New Zealand, USA. In Yellowstone National Park, the most attractive geysers are located. The most famous one is called "Old Faithful" and its booster jets break out at one-hour intervals. In Iceland, geysers are very useful: they are used to provide hot water for the central heating of the residents of the ...

Of all the animals we love, we probably love birds the most. They are often so wonderfully colorful and some sing beautifully. In addition, they are lively, agile and constantly on the move. Which is the first bird? The remains of the first bird were found in 1861 in limestone in Bavaria. The second skeleton was discovered in 1877 and almost a century later, in 1956, the third. Significantly, all three skeletons were found at a distance of 15 km. All three skeletons are thought to have belonged to the same species of Archaeopteryx lithographica, in short archeopteryx. This animal lived 150 million years ago. A weak flyer, it shared characteristics with its dinosaur ancestors. What are birds feathers made of?? If you look closely at the feather, you can see that its base is firm but very flexible at the top. It needs to be very mobile to be able to move in the air. In addition to this base, the feather consists of lateral fringes, "tiny silk twigs," hooked together...

In 1831, Charles Darwin, a young student of geology and botany, seized the opportunity he had of participating, as a naturalist, in an expedition around the world to continue his research. He visited the Galapagos Islands. In each of these islands, far apart from one another, he observed certain species that did not appear in the other islands of the archipelago. Charles Darwin discovered that nearby islands had similar but nonidentical species of finches. Moreover, he noted that each finch species was well-suited for its environment and role. When he returned to England, he read carefully his remarks from the journey he had carefully recorded in the logbook every day. Charles Robert Darwin (12 February 1809 – 19 April 1882) After many years of study and reflection, Darwin concluded that all of nature was changing. According to him, the strongest and most intelligent individuals are best able to adjust to changed environmental conditions and transfer to their offspring maintena...

Many animals do not seem particularly strange to us when viewed. But because, as soon as we see the giraffe, we can see at first glance all its strangeness, probably because of its long neck. The giraffe is without a doubt the tallest animal in the world. It is not uncommon for males to reach six meters in height (20 feet)! Its legs are extremely tall. And although her two pairs of legs are almost the same height, the front of her body is taller than the back and her back is lowered from neck to tail.   The giraffe's head is small and narrow, while the eyes, black and gentle, give this huge animal a noble expression. Giraffe's very elongated ears are sensitive to the slightest noise. The highly developed hearing and odor senses are very significant features and help the giraffe detect danger. Another particular interest in giraffes is their tongue, whose length is usually about 45 centimeters. The giraffe uses it very deftly; it rushes even the smallest leaves of barbed bu...

The diameter of a snake's body does not usually exceed the size of a fist, but it can still swallow a large chicken or rabbit. The Southeast Indian or nettle python is one of the largest snakes in the world, it can swallow wild boar and even deer. This is possible because the snake has very stretchy jaws, the shape of which is different from that of a human. Our lower jaw joints with the upper one are at ear height. For snakes, there is one extra bone that connects the ends of the two jaws with a double hinge, allowing them to be very separated from each other. The snake swallows its victim whole, covered with hair, feathers, shells, horns and more. Before the snake swallows its victim, it kills it first, whether using poison or more often, clamps it with her body until she chokes it. Because snakes teeth are bent backward, the snake must swallow the whole victim because it cannot chew or retrieve it.

As the egg-laying age approaches, the female turtle emerges from the water. It is difficult to navigate the coast looking for a safe place. Using her legs, which are used as fins in the water, she digs the ground to make a nest. In a few hours, the turtle will lay 100 to 150 eggs. Completely exhausted, there is so much power left to overwhelm them. After the eggs hatch, the turtle slowly returns to the sea. After a while, small turtles are born, which themselves have to cross a dangerous path to the sea where they can be killed by predators.

The remains of the first bird were found in 1861 in a limestone maid in Bavaria. The second skeleton was discovered in 1877 and almost a century later, in 1956, the third. Significantly, all three skeletons were found at a distance of 15 km. " Archaeopteryx lithographica (Berlin specimen) " by H. Raab ( User: Vesta ) - Own work . Licensed under CC BY-SA 3.0 via Commons . All three skeletons are thought to have belonged to the same species of Archaeopteryx lithographica, in short archeopteryx. It is named after the limestone in which it was discovered, and sometimes its called by its German name Urvogel, which means ‘first bird’ or ‘original bird’. This animal lived 150 million years ago.