Science textbook for grade 6 primary school Planets

The English name of Mercury comes from the Roman god Mercury. The symbol is a circle above, a short intersecting vertical line and a semicircle below (Unicode: ?). It is the shape of the wand held by Mercury. In the 5th century, Mercury was actually considered two different planets because it alternated between appearing on either side of the Sun. When it appeared in the evening it was called Mercury; but when it appeared in the morning it was called Apollo in honor of the sun god Apollo. Pythagoras later pointed out that they were actually the same planet. In ancient China, Mercury was called "Chenxing".

The ancient Chinese called Venus "Taibai" or "Taibai Venus", also called "Qiming" or "Chang Geng". The ancient Greeks called her Aphrodite, the goddess of love and beauty in Greek mythology. In Roman mythology, the goddess of love and beauty is Venus, so Venus is also called "Venus". The astronomical symbol of Venus is represented by Venus's vanity mirror. Phase changes of Venus: Like the moon, Venus also has periodic waxing and waning changes (phase changes), but because Venus is too far away from the earth, it cannot be seen with the naked eye. The phase changes of Venus were once used by Galileo as strong evidence to prove Copernicus' heliocentric theory.

The Earth is one of the planets in the solar system, ranking third in order from nearest to far from the sun. It is the largest terrestrial planet in the solar system and the only planet that modern science has confirmed to have life. The planet's age is estimated to be approximately 4.5 billion years (4.5×109). Soon after the planet formed, its only natural satellite, the moon, was captured. The only intelligent creatures on earth are humans.

Because it looks blood red in the night sky, it is named in the West after Mars, the god of war in Roman mythology (or Ares in Greek mythology). In ancient China, because it glowed like fire, it was called "Yinghuo". Mars has two small natural satellites: Phobos and Deimos (the names of Ares' sons). Both moons are small and oddly shaped and may be asteroids captured by gravity. The prefix areo- in English refers to Mars.

Jupiter is one of the nine planets in the solar system. It is the fifth planet in order from nearest to far from the sun. It is also the largest planet in the solar system and the fastest rotating planet. In ancient China, it was used to mark the year, so it was called the Sui Xing.

In the West, it is called Jupiter, the king of gods in Roman mythology, equivalent to Zeus in Greek mythology.

Saturn is a giant gas planet and the second largest planet in the solar system after Jupiter. The English name of Saturn (and the names of Saturn in most other European languages) is named after the Roman god of agriculture, Saturn. In ancient China, it was called Zhenxing or Star-filling.

Uranus is one of the nine planets in the solar system. It is ranked seventh outside Saturn and inside Neptune. It is gray-blue in color and is a gas giant. In terms of diameter, Uranus is the third largest planet in the solar system; but in terms of mass, it is lighter than Neptune and ranks fourth. Uranus is named after the god Uranus in Greek mythology.

Neptune is the eighth of the nine planets in the solar system and a giant planet. Neptune was the first planet discovered through celestial mechanics calculations. Because the orbit of Uranus was different from what was calculated, in 1845 John Cove Adams and Eban Quinvier calculated the possible location of an unknown planet beyond Uranus. On September 23, 1846, Johann Geffrian Gale, director of the Berlin Observatory, actually discovered a new planet at this location: Neptune.

Neptune is currently the second-farthest planet from the sun in the solar system. Neptune's name is Neptune, the god of the sea in Roman mythology.

Pluto is the farthest and smallest planet from the sun among the nine planets in the solar system. It was discovered in 1930. Because it is the farthest from the sun, it is also very cold. It is very similar to the place where Pluto, the god of the underworld, lived in Roman mythology, so it is called "Pluto".