Facts about Our Solar System
The regions of the Solar System consist of: [Click on each to learn more!]
1. Our Sun
Note: Pluto was demoted in 2006 from a Planet to Dwarf Planet.
How does the Solar System work?
The Sun is the center of our solar system and celestial bodies such as the planets, their moons, the asteroid belt, comets and other objects revolve around the Sun (gravitationally bound to it). The Sun contains around 98% of all the material in the Solar System.
The boundaries of the solar system's known planets fit within a sphere 50 AU in radius. Beyond that is the Oort Cloud which extends to a distance of 100,000 AU. Beyond that, the nearest star system is Alpha Centauri.
Note: The stars are not part of our solar system. Astronomers have discovered that some other stars, besides our own sun, have their own solar systems around them as well!
What is a Planet?
The International Astronomical Union (IAU) said that the definition for a planet is now officially known as "a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape and (c) has cleared the neighborhood around its orbit." At the same time, new moons are also being discovered, both around existing planets and within these mysterious new worlds. Once the existence of a moon is confirmed and its orbit determined, the moon is given a final name by the International Astronomical Union (IAU), the organization that assumed this task since 1919.
The planets all revolve around the Sun. Six of the eight planets are orbited by natural satellites (moons) after Earth's Moon and each of the outer planets is encircled by planetary rings of dust and other particles. All the planets except Earth are named after gods and goddesses from Greco-Roman mythology. The three dwarf planets are Pluto, the largest known Kuiper belt object; Ceres, the largest object in the asteroid belt and Eris, which lies in the scattered disc.
Planets in the Solar System:
In order of their distances from the Sun, the planets are:
4. Mars Calculate how much you'd weigh on these planets!!
6. Saturn What would your age be on other planets?
Last Modified on November 22, 2009