Tour the Solar System
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flagWhat you'll discover
- arrow_forwardName the eight planets in order from the Sun
- arrow_forwardTell the difference between rocky inner planets and giant outer planets
- arrow_forwardExplain why a year is shorter on Mercury than on Neptune
- arrow_forwardFind Earth and its Moon in the big family picture
One star, eight planets
Our solar system is a family of worlds travelling around one star — the Sun. The Sun is so huge that it holds 99.8% of all the mass in the solar system, and its gravity keeps everything else circling around it.
In order from the Sun, the planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. A fun way to remember them: "My Very Excellent Mother Just Served Us Noodles."
Rocky worlds and gas giants
The four planets closest to the Sun — Mercury, Venus, Earth and Mars — are small, rocky worlds with solid ground you could stand on. They are called the inner planets.
The four outer planets are completely different. Jupiter and Saturn are gas giants, enormous balls of hydrogen and helium with no surface at all. Uranus and Neptune are ice giants, cold and blue. Jupiter alone is so big that more than 1,300 Earths could fit inside it.
A year is a lap around the Sun
A "year" simply means one full trip around the Sun. Planets close to the Sun move faster and have a shorter path, so their years fly by — Mercury finishes a lap in just 88 Earth days.
Far-away planets crawl along huge orbits. Neptune needs about 165 Earth years for one lap, which means nobody could ever celebrate their first Neptune birthday! Earth takes 365.25 days, and that extra quarter day is why we add 29 Falgun... sorry, 29 February, every four years.
Try it in the simulation
In the 3D model, drag with one finger to orbit around the Sun, and pinch or scroll to zoom. Use the "Fly to" menu to visit each planet up close, then tap a planet to read its story.
Speed up time with the slider and watch how Mercury whizzes around while Neptune barely moves. The distances and sizes are squeezed so everything fits on screen — the real solar system is almost all empty space!