Our solar system consists of our star, the Sun, and everything bound to it by gravity – the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune; dwarf planets such as Pluto; dozens of moons; and millions of asteroids, comets, and meteoroids.

Venus is the second planet from the Sun and Earth’s closest planetary neighbor. Even though Mercury is closer to the Sun, Venus is the hottest planet in our solar system. Its thick atmosphere is full of the greenhouse gas carbon dioxide, and it has clouds of sulfuric acid. The atmosphere traps heat, making it feel like a furnace on the surface. It’s so hot on Venus, the metal lead would melt.

Venus is sometimes called Earth’s twin because it’s similar in size and structure, but the planets are very different in other ways. In addition to being extremely hot, Venus is unusual because it spins in the opposite direction of Earth and most other planets. It also has a very slow rotation making its day longer than its year.

Our home planet is the third planet from the Sun, and the only place we know of so far that’s inhabited by living things. While Earth is only the fifth largest planet in the solar system, it is the only world in our solar system with liquid water on the surface. Just slightly larger than nearby Venus, Earth is the biggest of the four planets closest to the Sun, all of which are made of rock and metal.

Mars is the fourth planet from the Sun – a dusty, cold, desert world with a very thin atmosphere. Mars is also a dynamic planet with seasons, polar ice caps, canyons, extinct volcanoes, and evidence that it was even more active in the past