The inner planets, Mercury, Venus, Earth and Mars, are important for study because they are so similar. All are terrestrial, meaning they have a solid surface. Mercury, being closest to the Sun, experiences the most intense solar radiation. Venus is an example of an extreme greenhouse environment, with temperatures nearing 1,000 degrees Fahrenheit. Mars offers us great hope for finding an environment that could have harbored extraterrestrial life. This book follows the Next Generation Science Standards focusing on the Earth and the solar system and shows readers that we can learn a lot about our own planet from our celestial neighbors.