Mercury is the closest planet to the sun. It is very hot. It is only 57,900,000 Km away from the sun. Each day lasts 59 earth days and a year lasts 88 earth days. Mercury is a world of extremes. Because it is so close to the Sun, a visitor could easily cook to death. However because Mercury spins so slowly it gets very cold in the night time, which means a visitor could also freeze to death. The average temperature on the lit side of the planet is 350°C (660°F). Mercury is so close to the Sun, and so small, that it has only a very small atmosphere. Its atmosphere has been blown away by the Sun’s solar winds. It means that there is almost no air on Mercury. Mercury has no moons. Due to its smaller size Mercury has lesser gravity. Therefore, if someone weighs 70 pounds on Earth, he would weigh only about 27 pounds on Mercury
Venus is the second planet from the sun. It is the planet closest to the earth. It is almost the same size as the Earth. Apart from the moon, Venus is by far the brightest object in the night sky. The temperature of the surface is 480°C. Its thick cloud cover makes it impossible to see the surface, and traps much of the Sun’s heat. This extra heat gives Venus the hottest average temperature of all the planets. There were once oceans on Venus but these have long since boiled away due to the great heat on the surface. In its early days, Venus was just like the Earth. It had oceans and may even have held life, but as it has so much carbon dioxide now, that life is not possible any more. In many ways Venus is similar to the Earth. It has active volcanoes, Venus quakes, mountains and valleys. The major difference is that Venus’s atmosphere makes the planet far too hot for life. Aside from the fact that Venus rotates very slowly so that a day on Venus actually lasts longer than a year, Venus also rotates in the opposite direction as almost all the other planets. Due to this reason, the Sun instead of rising in the east and setting in the west, would appear to rise in the West, and set in the East on Venus.
Our planet ‘Earth’ is an oasis of life in an otherwise desolate universe. The Earth’s temperature, weather, atmosphere and many other factors are just right to keep us alive. Earth is the 5th largest planet in our solar system. It is located at third position from the sun. Earth’s mass is 6.0 x 1024 Kg. Its atmosphere mainly contains 78.084% Nitrogen and 20.946% Oxygen. It takes 24 hours to rotate on its axis and 365 days to complete its one orbit around the sun. LUNA, the earth’s moon is our closest neighbor. Its average distance from earth is 384,000 km (239,000 miles). The moon takes 27 days to travel around the earth. This is the only planet we know which has life.