The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth.
Mercury
Mercury is the closest planet to the sun and the eighth largest. It has a diameter of 4,880 kilometers. Mercury has the widest temperature extremes in the solar system ranging from 90 degrees Kelvin to 700 degrees Kelvin. Mercury has a thick iron core and a thinner outer crust of rocky material.
Venus
Venus is the second planet from the Sun, and is Earth's closest neighbor in the solar system. Venus is the brightest object in the sky after the Sun and the Moon, and sometimes looks like a bright star in the morning or evening sky. The planet is a little smaller than Earth, and is similar to Earth inside.
Earth
Earth, our home, is the third planet from the sun. It's the only planet known to have an atmosphere containing free oxygen, oceans of water on its surface and, of course, life. Earth is the fifth largest of the planets in the solar system.
Mars
Mars is the fourth planet from the Sun and is the second smallest planet in the solar system. Named after the Roman god of war, Mars is also often described as the “Red Planet” due to its reddish appearance. Mars is a terrestrial planet with a thin atmosphere composed primarily of carbon dioxide.
Jupiter
Jupiter is called a gas giant planet. Its atmosphere is made up of mostly hydrogen gas and helium gas, like the sun. The planet is covered in thick red, brown, yellow and white clouds. The clouds make the planet look like it has stripes.
Saturn
Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine times that of Earth. It only has one-eighth the average density of Earth; however, with its larger volume, Saturn is over 95 times more massive.
Uranus
Uranus is blue-green in color, as a result of the methane in its mostly hydrogen-helium atmosphere. The planet is often dubbed an ice giant, since at least 80% of its mass is a fluid mix of water, methane and ammonia ice.
Neptune
Neptune is very similar to Uranus. It's made of a thick soup of water, ammonia, and methane over an Earth-sized solid center. Its atmosphere is made of hydrogen, helium, and methane. The methane gives Neptune the same blue color as Uranus.
