Venus, a veiled neighbor, sometimes sees a particularly bright "morning star" on the eastern horizon around dawn, which people call "morning star"; At dusk, a very bright "evening star" sometimes appears in the afterglow of the west, which is called "Chang Geng Star". These two stars are actually one, namely Venus. Venus is one of the eight planets in the solar system, and it is the second planet from near to far from the sun. It is the closest planet to the earth.
Venus is called "Taibai" or "Taibai Venus" in China. In ancient mythology, "Taibai Venus" was a god. The ancient Greeks called Venus "Aphrodite", the goddess representing love and beauty. The Romans called this goddess "Venus", so Venus is also called Venus.
Besides the sun and the moon, Venus is the brightest star in the whole day, with the maximum brightness of -4.4, which is 14 times brighter than the famous Sirius (the brightest star except the sun). Venus has no satellites, so there is no "moon" in the night sky on Venus, and the brightest "star" is the earth. Because it is close to the sun, the size of the sun seen from Venus is 1.5 times larger than that seen from the earth.
Some people say that Venus is the twin sister of the earth. Indeed, from the structural point of view, Venus and the Earth have many similarities. Venus has a radius of about 6,073 kilometers, only 300 kilometers smaller than radius of the earth, its volume is 0.88 times that of the Earth, and its mass is 4/5 of that of the Earth. The average density is slightly less than that of the earth. But the environment between them is very different: the surface temperature of Venus is very high and there is no liquid water. Coupled with cruel natural conditions such as extremely high atmospheric pressure and severe hypoxia, Venus cannot have any life. So Venus and the Earth are just sisters.
In the atmosphere of Venus, carbon dioxide is the most, accounting for more than 97%. At the same time, there is a layer of concentrated sulfuric acid with a thickness of 20 to 30 kilometers. The surface temperature of Venus is as high as 465 to 485 degrees, and the atmospheric pressure is about 90 times that of the Earth.
Venus's rotation is very special. Its rotation direction is opposite to that of other planets, from west to east. Therefore, on Venus, the sun rises in the west and sets in the east. It takes 243 days to rotate once, but the day and night on Venus are particularly long, which is equivalent to 1 17 days on Earth. This means that Venus only has two days in a year, and only two days can be seen in a year. Venus's orbit around the sun is an ellipse that is very close to a perfect circle. Its revolution speed is about 35 kilometers per second, and period of revolution's is about 224.70 days. Venus's orbit is very close to a perfect circle and coincides with the ecliptic plane. Its period of revolution is about 224.7 days, but its rotation period is 243 days. That is to say, Venus's "one day" is longer than its "one year". Venus is the only big planet in the solar system that rotates in the opposite direction. Besides, like Mercury, it is the only two planets in the solar system without natural satellites.
There is a dense atmosphere and clouds around Venus. These clouds cast a mysterious veil on the surface of Venus. Only with the help of radio telescopes can we cross this atmosphere and see the true face of Venus. The moon is also called "the moon". Before the invention of the telescope, ancient people could only look up at the bright moon with their eyes on clear nights. Seeing the bright and dark surface and strange shape of the moon, people made up beautiful myths such as the Goddess Chang'e flying to the moon, Wu Gang cutting Guangxi, and Yu Mian tinkering with medicine. The ancient Greeks regarded the moon as the beautiful hunting goddess themis, and regarded the silver bow that the goddess never left when hunting as the astronomical symbol of the moon.
There is basically no water on the moon, so there is no weathering, oxidation and water corrosion on the earth, and there is no sound transmission. There is a silent world everywhere. The moon itself does not shine, the sky is always dark, and the sun and stars can appear at the same time.
There is almost no atmosphere on the moon, so there is a great temperature difference between day and night on the moon. During the day, where the sun shines vertically, the temperature is as high as127.25℃; The temperature at night can be as low as-183.75℃. Because there is no atmospheric barrier, the intensity of sunlight on the surface of the moon is stronger than that on the earth 1/3 or so. The intensity of ultraviolet rays is also much stronger than the surface of the earth. Due to the lack of atmosphere on the moon, many strange phenomena will be seen on the moon, such as the dark sky on the moon, direct sunlight and brilliant sunshine; It's dark where you can't shine. Therefore, we can see that the surface of the moon is bright and dark. As there is no air to scatter light, the stars on the moon no longer seem to twinkle.
The moon is full of exposed rocks and the outline of craters. The whole surface of the moon is covered with gravel and residual soil. The surface of the moon seen from the earth has bright areas and dark gray parts. The original bright part is the mountains and highlands on the surface of the moon, and the dark gray part is the plain on the surface of the moon.
The moon is smaller than the earth, with a diameter of 3476 kilometers, which is about 3/ 1 1. The surface area of the moon is about114 of the surface area of the earth, slightly smaller than that of Asia. Its volume is 1/49 of the earth, in other words, the earth has 49 satellites. The mass of the moon is1/81of the earth; The average density of matter is 3.34 grams per cubic centimeter, which is only 3/5 of the density of the earth. The gravity on the moon is only 1/6 of that of the earth, that is to say, something weighing 6 kilograms will only weigh 1 kg on the moon. When people walk on the moon, their bodies look relaxed and they can jump up with a little effort. Astronauts think that walking on the moon seems more enjoyable than walking on the earth.
The moon is the closest celestial body to the earth. It is the only natural satellite orbiting the earth, with an average distance of about 384,400 kilometers. The moon's orbit around the earth is circular, with an average distance of 363,300 kilometers at perigee (when it is closest to the earth) and 405,500 kilometers at apogee (when it is farthest from the earth), with a difference of 42,200 kilometers. The moon, like the earth, is a flat sphere with slightly flat north and south poles and slightly higher equator. Its average polar radius is 500 meters shorter than the equatorial radius, and the north and south poles are also asymmetrical. The North Pole rises and the South Pole sinks about 400 meters.
When the moon goes around the earth, it also goes around the sun with the earth. That is to say, after the moon orbits the earth once, the space position it returns to is not the original starting point. It can be seen that the moon should participate in the movement of various systems in the process of movement. Like other celestial bodies, the moon is always in motion. The moon moves from west to east by more than 13 degrees on average every day, so the moon rises about 50 minutes later than the previous day. The rise and fall of the moon is a reflection of the earth's rotation; The movement from west to east is the result of the moon's revolution around the earth. One revolution of the moon around the earth is called "sidereal moon", with an average of 27 days, 7 hours and 43 minutes 1 1 sec. When the moon revolves around the earth, it also rotates. The moon's rotation period is equal to period of revolution, that is, 1: 1, and the time for the moon to go around the earth is the rotation period.
As a result of this strange rotation of the moon, the moon always faces the earth with the same half, and what the back of the moon looks like can never be seen from the earth. Only through the detector can we solve the mystery on the back of the moon. This wish of mankind was realized as early as 30 years ago. Today's large astronomical telescopes can distinguish targets about 50 meters (equivalent to 14-story buildings) on the moon.