Our solar system consists of our star, the Sun, and everything bound to it by gravity. Eight giant planets, smaller dwarf planets, and millions of pieces of rocks and ice orbit the Sun. Moons can also be found within the solar system; they are held in orbit around planets by gravity.
To better understand the solar system…
LET’S BREAK IT DOWN!
Gravity in Our Solar System
Eight planets orbit the Sun and are held in place due to gravity. Gravity is the attractive force by which a planet or other body draws objects toward its center. Anything that has mass also has gravity. The larger an object’s mass, the larger its gravitational is on another object. Since the mass of the Sun is so large compared to the planets, its force of gravity keeps all of the planets in orbit around it.
Gravity also keeps other bodies in orbit, such as moons. Moons most often orbit a planet, but even a large space rock (asteroid) can hold a small moon in orbit due to the gravitational pull between the two objects. Gravity also holds the rock and ice that make up Saturn’s rings in orbit.
Size and Order of the Planets
The four planets in our solar system that are closest to the Sun are called terrestrial planets. These are smaller planets, mostly made of a compact rocky surface and metals like Earth. The terrestrial planet closest to the Sun is Mercury, which is very hot and lacks an atmosphere. Moving outward are Venus, Earth, and Mars. Each has a significant atmosphere with varying environments due to differences in the gases present, temperatures, size, mass, and whether life is present.
The four larger planets in the outer part of the solar system (past the orbit of Mars and the asteroid belt) are called gas giants. Gas giants are made mostly of gases with a small rocky core. Jupiter is the gas giant closest to the Sun, followed by Saturn, Neptune, and Uranus.
There are also many dwarf planets in our solar system. A dwarf planet has enough mass to be round in shape and orbit the Sun, but does not have enough mass to clear the neighborhood around its orbit of other objects, and is not a moon. Pluto was reclassified as a dwarf planet in 2006.