The Solar System

What is the solar system? It is our Sun and everything that travels around it. Our solar system is elliptical in shape. That means it is shaped like an egg. The Sun is in the center of the solar system. Our solar system is always in motion. Eight known planets and their moons, along with comets, asteroids, and other space objects orbit the Sun. The Sun is the biggest object in our solar system. It contains more than 99% of the solar system's mass. Astronomers think the solar system is more than 4 billion years old.

Astronomers are now finding new objects far, far from the Sun which they call dwarf planets. Pluto, which was once called a planet, is now called a dwarf planet.

The Solar System

The Solar System consists of the Sun those celestial bound to it by gravity. These objects are the eight planets and their 166 known moons; three dwarf planets (Ceres, Pluto, and Eris) and their four known moons; and billions of small bodies, including asteroids, Kuiper belt objects, comets, meteoroids, and interplanetary dust.

In broad terms, the charted regions of the Solar System consist of the Sun, four terrestrial inner planets, an asteroid belt composed of small rocky bodies, four gas giant outer planets, and a second belt, the Kuiper belt, composed of icy objects. Beyond the Kuiper belt is the scattered disc, the heliopause, and ultimately the hypothetical Oort cloud.

In order of their distances from the Sun, the terrestrial planets are:

• Mercury
  
• Venus
  
• Earth
  
• Mars
  

The outer gas giants (or Jovians) are:

• Jupiter
  
• Saturn
  
• Uranus
  
• Neptune
  

The three dwarf planets are

• The asteroid belt.
• Pluto, the largest known object in the Kuiper belt.
• Eris, the largest known object in the scattered disc.

Six of the eight planets and two of the dwarf planets are in turn orbited by natural satellites, usually termed "moons" after Earth's Moon, and each of the outer planets is encircled by planetery rings of dust and other particles. All the planets except Earth are named after deities from Greco-Roman mythology.