Named after the winged messenger of the gods, Mercury is a small planet that rotates quickly. It is a barren planet that has a surface that ranges between two extremes – frigid and burning temperatures – because it has no atmosphere to hold in the heat when the planet is facing away from the Sun.
Venus is an interesting planet with the hottest temperatures of any planet in our Solar System at more than 460°C. Some astronomers actually believed that Venus used to be like Earth with oceans and a habitable environment until the planet’s atmosphere underwent an out of control greenhouse effect. The massive amounts of carbon dioxide in its atmosphere is mostly responsible for the planet’s raging temperatures.
Earth is the densest planet in our Solar System as well as the fifth largest planet. Not only is 70% of the Earth’s surface covered with water, but the planet is also in the perfect spot – in the center of the hypothetical habitable zone – to support life.
Roughly half the size of Earth, Mars is famous for its red color and the speculation it has sparked about life on other planets. The red color is caused by iron oxide – rust – on the planet’s surface.
Jupiter’s size is almost unbelievable. It is possible to fit 1321 Earths inside of Jupiter. Despite its size, Jupiter is not very dense. The planet is comprised almost entirely of gas with what astronomers believe is a liquid metal core. The only reason it is the most massive planet is because it is so much larger than any of the other planets.
Saturn is best known for its ring system, which is composed of rocks, dust, and other materials. However, the planet is also the second largest in our Solar System. Our view of Saturn’s rings is always changing and sometimes they seem to disappear in the planet’s orbit around the Sun.
Here’s a picture of Uranus taken by Voyager 2. Uranus is an ice giant meaning it has more “ices,” such as methane and ammonia, in its atmosphere than other gas giants like Jupiter have. Ice giants are a subcategory of gas giants. The methane is also what gives Uranus its blue color.
Neptune is also an ice giant. All of the gas giants have intense storms, but Neptune has the fastest winds of any planet in our Solar System. The winds on Neptune can reach up to 24,000 kilometers per hour. In comparison, the top winds on Earth only reach a little more than 250 kilometers per hour in the strongest hurricanes.
Astronomy Cast has episodes on all of the planets including Mercury.