The earth rotates from west to east and revolves around the sun at the same time. The combination of the earth's rotation and revolution has produced the alternation of day and night and seasonal changes on the earth (the speed of the earth's rotation and revolution is uneven). At the same time, due to the gravity of the sun, the moon and nearby planets, as well as the influence of many factors such as the earth's atmosphere, ocean and materials inside the earth, the direction of the earth's rotation axis will change in space and the earth itself. The inertial centrifugal force produced by the earth's rotation makes the spherical earth gradually expand from the poles to the equator, becoming a slightly flat ellipsoid of revolution at present, and the polar radius is about 2 1 km shorter than the equatorial radius.
Apollo spacecraft saw on the moon that the earth was composed of a series of concentric layers. The earth has a core (core), mantle (mantle) and crust (crust) structure. There are hydrosphere, atmosphere and magnetosphere outside the earth, forming a beautiful coat around the solid earth.
As a planet, the earth was born in the primitive solar nebula 5.6 billion years ago.
Basic parameters of the earth:
Equatorial radius: ae = 6378 136.49.
Polar radius: ap = 6356755.00 meters.
Average radius: a = 637 100 1.00 m.
Equatorial gravity acceleration: ge = 9.780327 m/s 2.
Average rotational angular velocity: ω e = 7.29115×10-5 radians/second.
Flatness: f = 0.0033528 19.
Mass: m ⊕ = 5.9742×1024kg
Geocentric gravitational constant: ge = 3.986004418×1014m3/S2.
Average density: ρ e = 5.5 1.5g/cm3.
Mass ratio of the sun to the earth: S/E = 332946.0.
The mass ratio of the sun to the earth-moon system: s/(m+e)= 328900.5.
Revolution time: T = 365.2422 days.
Average distance from the sun: a =1.49597870×101m.
Revolution speed: v =11.19 km/s.
Surface temperature: t =-30 ~+45.
Ground atmospheric pressure: p = 10 13.250 mbar.
Surface gravity acceleration (equator) 978.0 cm/s 2
Surface gravity acceleration (polar) 983.2 cm/s 2
The rotation period is 23: 56: 4 (when the sun is flat).
The half-length diameter of the orbit is 149597870 km.
The eccentricity of the orbit is 0.0 167.
Period of revolution 1 sidereal year
The intersection of yellow and red is 23 degrees and 27 minutes.
The structure of the earth's sphere
The ocean area of the earth is 36 1745300 square kilometers.
The crust is 80.465 kilometers thick.
The depth of the mantle is 2808.229 km.
The core radius is 3482.525 kilometers.
The surface area is 5 10067866 km2.
It was not until recently that people clearly knew the structure of the earth. The whole earth is not an isotropic body, but has an obvious circular structure. The composition, density and temperature of each layer of the earth are different. In astronomy, studying the internal structure of the earth is of great significance for understanding the movement, origin and evolution of the earth, exploring the structure of other planets, and even the origin and evolution of the whole solar system.
The sphere of the earth is divided into two parts: the outer ring and the inner ring. The outer circle of the earth can be further divided into four basic circles, namely, atmosphere, hydrosphere, biosphere and lithosphere; The inner circle of the earth can be further divided into three basic circles, namely mantle circle, outer nuclear liquid circle and solid inner circle. In addition, there is a asthenosphere between the outer and inner circles of the earth, which is the transition layer between the outer and inner circles of the earth and is located at an average depth of about 150 km below the ground. In this way, the whole earth contains eight spheres, in which the lithosphere, asthenosphere and the inner circle of the earth together constitute the so-called solid earth. The atmosphere, hydrosphere, biosphere and lithosphere surface in the outer circle of the earth are generally studied by direct observation and measurement. At present, the research on the inner circle of the earth mainly adopts geophysical methods such as seismology, gravity and high-precision modern space geodetic observation inversion. The distribution of spheres on the earth has a remarkable feature, that is, the interior of the solid earth and the altitude above the surface are basically parallel up and down, while near the surface of the earth, spheres are interspersed or even overlapped with each other, among which the biosphere is the most obvious, followed by the hydrosphere.
Our home-the earth
What is the shape of the earth? Where is she from? As early as 6.5438+0.7 million years ago, human beings had all kinds of beautiful daydreams about their home-the earth, which were woven into many colorful legends. There is a story about Pangu's creation in ancient China. When talking about the creation of the world, ancient Greek mythology said that the universe was born out of chaos, and the first god to appear was Gaia, the god of the earth. The sky, land and sea are all born of her, so people respectfully call her "Mother Earth".
The earth is already the 5000-year-old birthday girl, which originated in Pangu. About 5000 years ago, heaven and earth were connected, and then gradually evolved, and various creatures appeared. The average equatorial radius of the earth is 6378. 14 km, which is 2 1 km longer than the polar radius.
The internal structure of the earth can be divided into three layers: crust, mantle and core. Under the action of the earth's gravity, a large number of gases gather around the earth to form a blanket, which is the earth's atmosphere.
The earth is like a top, rotating from west to east along its axis of rotation. Her rotation period is 23 hours, 56 minutes and 4 seconds, which is about 24 hours. At the same time, the earth revolves around the sun, and its orbit is elliptical, with a half-length of 149597870 km. One revolution takes 365.25 days, which is one year.