Planets are large bodies that rotate around the sun. The inner planets, or terrestrial planets, are the four planets closest to the Sun: Mercury, Venus, Earth, and Mars. Even though these planets are all small and rocky, they have more differences than they have things in common. Because Mercury is the closest to the sun, the side that faces the sun gets as hot as 427° Celsius. At the same time, the side that faces away from the sun is a freezing -173° Celsius. The extreme temperatures alone make it a very unlikely place for life. With an atmosphere too thin for human breathing, its obvious that people wont be living on Mercury any time soon. The next planet from the sun is Venus. Below clouds of sulfuric gas lies 96% carbon dioxide atmosphere. That might be nice for a plant, since a plant breathes carbon dioxide, but not for a person. If you managed to survive the atmosphere, the surface of the planet is hot enough to melt solid metal. Venus has a temperature that is maintained at 462° Celsius, no matter where you go on the planet. You are probably most familiar with Earth because it is your home planet. It has the perfect conditions for life. Earths atmosphere and oceans help control the trickiest part of making a planet life-friendly: temperature. Earth is the only planet known to have liquid water. Mars is the fourth farthest from the sun. Some people think it may be possible for life to exist there. Although scientists have not been able to find actual water on Mars, there seems to be evidence of water erosion on its surface. Its canyons and mountains are very similar to those found on Earth. The main difference is that there is no plant life. Some scientists believe that Mars may have been very much like Earth until something happened that made the water supply evaporate. A. Decide if the statements are true (T) or false (F). 1. The inner planets are located closest to the sun. 2. Mercury is the hottest planet because its the closest to the sun. 3. Venus has an atmosphere whose composition is similar to that of Earth. 4. The temperature on the surface of Venus is hot enough to melt lead. 5. Earth has a surface temperature that is uniquely friendly to life. 6. Scientists have proved that life once existed on Mars. 7. It seems that Mars once had liquid water on its surface. 8. Some scientists believe that Mars is very similar to the Earth.