As of November 2026, our solar system has eight planets that circle the Sun, and the Sun is at the center. About 1.3 million Earths could fit inside the Sun, and it holds 99.8 percent of all the mass in our solar system.
The Sun moves too. It formed about 4.6 billion years ago from a giant spinning cloud of gas and dust. Today it orbits the center of the Milky Way galaxy and carries the planets, asteroids and comets with it.
You may have heard that planets travel around the Sun in perfect circles. In fact, planets travel in oval-shaped paths called ellipses. Mercury is the smallest planet and the planet closest to the Sun, and it goes around the Sun in just 88 Earth days. That is faster than any other planet. Planets spin as well as circle. A day on Jupiter lasts only about ten hours, the shortest day of any planet, while a day on Mars lasts about 24.6 hours, very close to a day on Earth.
Venus spins so slowly that one Venus day, about 243 Earth days, is longer than a Venus year. Uranus appears to spin sideways as it goes around the Sun. Earth moves in more than one way, too. It is the third planet from the Sun, and its axis is tilted by about 23 degrees from the plane of its orbit, which gives us seasons. Some people think summer comes when Earth moves closer to the Sun, but the tilt is what gives us seasons.
There is a belt of asteroids, which are rocky space rocks, between Mars and Jupiter. More than a million asteroids orbit the Sun in this main belt. The belt is made of bits and pieces left over from the early solar system that never came together into a planet.
Neptune is the windiest world in our solar system. Jupiter's Great Red Spot is a giant storm that is bigger than Earth.
The gaps between worlds are wide. The Sun is about 93 million miles (150 million kilometers) from Earth, and sunlight takes about eight minutes to reach Earth. Voyager 1 entered interstellar space in August 2012.
Words to know
- ellipses: oval paths
- axis: spin line
- orbits: goes around
- interstellar: between stars
- galaxy: huge star group
