Earth's Autobiography

Earth's Autobiography

The earth was formed about 4.5 billion years ago. This rocky planet was originally just dust floating in space. The dust originated from the big bang of a giant old star at the end of its life
Since its formation, the earth can also be divided into five "generations", which are Archean, Proterozoic, Paleozoic, Mesozoic and Cenozoic, For example, the Paleozoic is divided into Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian from far to near; the Mesozoic is divided into Triassic, Jurassic and Cretaceous; the Cenozoic is divided into tertiary and Quaternary. This is the most rough division of the earth's historical period, which we call "geological age". Different geological ages have different characteristics
In Archean times, 2.4 billion years ago, primitive lithosphere, hydrosphere and atmosphere had been formed on the earth's surface. But at that time, the crust was very unstable, volcanic activities were frequent, magma overflowed everywhere, the sea area was vast, and the land was full of barren hills. This was an important time for the formation of iron ore, and the lowest primitive life began to emerge
Proterozoic, 2.4-600 million years ago. At that time, most of the earth was still covered by the ocean. In the late stage, a large area of land appeared on the earth. "Proterozoic" means the age of primitive life, when marine algae and marine invertebrates appeared
600-250 million years ago is the Paleozoic era. "Paleozoic Era" means the age of ancient life. At this time, thousands of species of animals appeared in the ocean, and marine invertebrates flourished unprecedentedly, They became the ancestors of land vertebrates. Amphibians also appeared. Ferns appeared on the land of the northern hemisphere, some as high as 30 meters. These tall and dense forests later became large coalfields
The Mesozoic era, 250-700 million years ago, lasted about 180 million years. This is the era of reptiles. Dinosaurs once dominated for a time, but primitive mammals and birds also appeared. Ferns gradually declined and were replaced by gymnosperms. The lush plants and huge animals in the Mesozoic era later became many huge coal fields and oil fields. Many metal deposits were also formed in the Mesozoic era
The Cenozoic era is the latest stage in the history of the earth, with the shortest time, only about 70 million years ago. At this time, the face of the earth is basically similar to today's situation. The great development of angiosperms in the Cenozoic era led to the unprecedented prosperity of various herbivorous and carnivorous mammals, Human beings appeared in the Quaternary, about 2.4 million years ago
The earth in which human beings live has evolved step by step until now, gradually forming today's appearance
Why is the earth round?
The earth is round, so are other planets. The water droplets we see are round in the air. The bubbles are round, too
Due to the surface tension of the liquid, the bubbles and water droplets are round
The reason why the earth is round begins with the birth of the earth. The original universe was a high-temperature, high-energy, high-density material. Due to the big bang, various planets were produced. At that moment, those stars were high-temperature liquid. Also due to the effect of surface tension, these stars were round. After hundreds of billions of years of cooling, the surface temperature of some stars gradually decreased, and then slowly produced protein, Life came into being, and this planet is the earth. In the later movements, there is no reason to change it into other shapes, so it has been round until now
How big is the earth?
Earth, the planet in which human beings live, is one of the eight major planets in the solar system. Its average distance from the sun is 149597870 km (1 astronomical unit), ranking third among the planets. Its equatorial radius is 6378.2 km, and its size ranks fifth among the planets
The earth's equatorial radius (a) is 6378.140 km
The earth's polar radius (b) is 6356.755km
The average radius of the earth R (3 A2B) is 6371.004 km
Equatorial perimeter (2 Γ a) 40075km
The earth area is 510100934 square kilometers
The volume of the earth is 4 π R 311082 billion cubic kilometers = 1.083 207 3 × 10 ^ 12 km ^ 3
Earth mass: 5.9742 × 10 ^ 24 kg
Average density: 5515.3 kg / m ^ 3
Equatorial surface acceleration of gravity: 9.780 1 m / S ^ 2 (0.997 32 g)
The temperature of the earth
The temperature of the earth's core is about 6880 ℃, which is higher than the surface temperature of the sun's photosphere (6000 ℃), It's much hotter than the sun's core (14 million degrees Celsius). Where's the coldest place on earth? The "cold pole" in the northern hemisphere is in oimyakon, eastern Siberia. The lowest temperature in January 1961 is – 71 ℃. The "cold pole" in the southern hemisphere is in Antarctica. The temperature on August 24, 1960 is – 88.3 ℃
The electricity of the earth
With negative charge
Reason: the earth rotates from west to East, and the outer part of the geomagnetic field points from the magnetic south pole to the magnetic north pole (that is, the north pole points to the south pole). The circular current formed is opposite to the direction of the earth's rotation, so it is negatively charged