The Solar System is made up of eight planets and a variety of other objects that orbit the Sun. These include rocky planets, gas giants, dwarf planets and asteroids.
The entire planetary system moves around the Sun in a prograde motion – one that is in the same direction as the Sun’s rotation. This motion happens at a speed of 1.3 million miles per hour.
The Sun is a 4.5 billion-year-old star that has eight planets orbiting it in a tight disk. Beyond the most distant planet, Neptune, is a donut-shaped region of minor planets, asteroids and comets called the Kuiper Belt.
During the earliest days of our solar system, the young Sun smashed together tiny particles of rock and ice. They began to accrete, gradually forming the eight stable planets we know today.
Throughout our journey through space, Earth’s axis tilts slowly over time, called precession, which affects where it aims in the sky and what happens to the surface of our planet.
The Sun is the center of our solar system and is part of a much larger collection of stars in the Milky Way galaxy. It orbits 25,000 light-years from the galactic center and completes one revolution every 250 million years.
Our Sun is powered by the process of fusion, wherein hydrogen gas is fused to helium at high temperatures and pressures. The energy released during this process is emitted as light and heat.
The Moon orbits our planet at a distance of 384,000 km (238,600 miles).
It’s the fifth largest natural satellite in our solar system.
It formed when chunks of Earth flew off into space after a giant impact. Scientists have studied rocks and meteorites to learn how and why the moon formed.
Mars is the closest planet to the Sun at 141 million miles (275 million kilometers). It takes 687 Earth days to orbit our star.
It has a rocky surface with volcanoes, canyons and craters. Red dust covers much of it.
Mars also has weather that is similar to Earth’s, including wind and dust storms. These winds are driven by solar heat.
Jupiter is the largest planet in our solar system, with a diameter more than double that of Earth. It takes 12 Earth years to orbit the Sun and rotates once a day.
The gas giant’s rotation causes its clouds to clump together into distinct belts and zones, as well as massive storm systems like the Great Red Spot. It has a narrow ring system and more known moons than any other planet in the solar system.
Saturn is a gas giant that took shape in the outer solar system 4.5 billion years ago. Its core formed first, then gravity pulled swirling gas and dust into a dense atmosphere.
Saturn’s atmosphere isn’t solid like Earth’s, but it resembles an ocean, with layers that overlap on top of each other. As the pressure builds, lighter elements such as ammonia and methane combine into heavier ones. These changes form a layer of hazy yellow ice over the planet’s surface.
Like Jupiter and Saturn, Uranus is an ice giant. It has a thick slush of partially frozen water, ammonia, and methane beneath its icy surface, and its atmosphere is a mixture of hydrogen and helium with traces of methane that absorb red wavelengths of sunlight and give it its distinctive blue-green color.
Until 1986, when Voyager 2 flew past it and studied its atmosphere, rings, and moons, Uranus was virtually unknown. Now planetary scientists are calling for NASA to build a flagship mission to study it in depth.
Neptune is a giant planet that formed near the Sun about 4.5 billion years ago. It settled into its current orbit in the outer reaches of the Solar System, and it is now about 30 times farther from the Sun than Earth.
Neptune’s atmosphere is mostly hydrogen and helium, with a tiny amount of methane gas. Methane absorbs red light, but lets blue pass through, giving Neptune its beautiful blue color.