The nine planets of our solar sistem
Mercury is the first planet in the solar system. Mercury is only a bit larger than Earth's moon. Mercury hasn’t atmosphere to absorb meteor impacts, so its surface is pockmarked with craters, just like the moon. It is visible to the naked eye. Mercury was the messenger of the Roman gods. Mercury is the only planet where the day lasts most of the year, because its his motion of revolution is much faster than the Earth.
The second planet from the sun is Venus. Venus is terribly hot, even hotter than Mercury. The atmosphere is toxic. Its size and structure are similar to Earth, Venus spins slowly in the opposite direction of most planets. Venus was Roman goddess of love and beauty. It hasn’t satellites. Its surface is composed of few large craters
The Earth is the third planet from the sun, Earth is a waterworld, with two-thirds of the planet covered by ocean. It’s the only world where we know the life. Earth’s atmosphere is rich of nitrogen and oxygen. Earth has one satellite, the Moon.
The fourth planet from the sun, is a cold, dusty place. The dust, an iron oxide, gives the planet its reddish cast. Mars shares similarities with Earth: It is rocky, has mountains and valleys. Mars's atmosphere is too thin for liquid water to exist on the surface for any length of time. Scientists think ancient Mars would have had the conditions to support life, and there is hope that signs of past may exist on the Red Planet. It was the Roman god of war. One day is just more than one Earth day (24 hours, 37 minutes).
The fifth planet from the sun, Jupiter is huge and is the most massive planet in our solar system. It’s a mostly gaseous world, mostly hydrogen and helium. Jupiter has a strong magnetic field, and with dozens of moons, for example Io, Callisto and Europa. Jupiter has sixty-seven satellites and four rings. It was King of the Roman gods.
The sixth planet from the sun is known most for its rings, sixteen. The gaseous planet is mostly hydrogen and helium. It has sixty-two moons. It was the Roman god of agriculture. Saturn has sixty-two satellites and sixteen rings.
The seventh planet from the sun. Astronomers think the planet collided with some other planet-size object long ago, causing the tilt. Uranus is about the same size as Neptune. Methane in the atmosphere gives Uranus its blue-green tint. It has twenty-seven moons and thirteen rings. It was discovery in 1781 by William Herschel. It was the god of the sky.
The eighth planet from the sun. Neptune is far out and cold. It has a rocky core. German astronomer Johann Galle used calculations to help find Neptune in a telescope. Neptune is about 17 times as massive as Earth. Neptune was the Roman god of the sea. It has fourteen satellites and ten rings
Once the ninth planet from the sun, Pluto is unlike other planets in many respects. It is smaller than Earth's moon. Its orbit carries it inside the orbit of Neptune and then way out beyond that orbit. Pluto’s orbit is tilted to the main plane of the solar system, where the other planets orbit. It’s a cold, rocky world with only a very ephemeral atmosphere. Since 2006 Pluto is dwarf planet. It was the Roman god of the underworld.