The Solar System Ch.11

Sun Facts The largest object in our solar system It is a star! It’s diameter is 10x that of Jupiter (our largest planet) Makes up 99% of mass in the entire solar system!

The Sun Inside the Sun, nuclear fusion produces A LOT of energy! The Sun emits some of this energy in the form of light Gravitational forces cause the planets and other objects to move around, or orbit, the Sun.

Why Does Everything in Our Solar System Orbit the Sun?

Name the Planets in Order From the Sun Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune

Planets A planet is an object that orbits the Sun and has a nearly spherical shape. The mass of a planet must be much large than the total mass of all other objects whose orbits are close by.

What are the Inner Planets? Mercury, Venus, Earth, Mars Made of mainly solid rock (we call them the rocky planets) These planets are much smaller

Outer Planets Jupiter, Saturn, Uranus, Neptune Mostly made of gases (gassy planets) Have rings (even if you can’t see them) Have moons Are much larger

Dwarf Planets A dwarf planet is a spherical object that orbits the Sun Unlike a planet, a dwarf planet does not have more mass than objects in nearby orbits. Made up of rock and ice

Asteroids Millions of small, rocky objects called asteroids orbit the Sun in the asteroid belt between the orbits of Mars and Jupiter. Asteroids range in size from less than a meter to several hundred kilometers in length. Usually not spherical

Comets A comet is made of gas, dust, and ice that moves around the Sun in an oval-shaped orbit. Comets come from outer parts of the solar system. There might be up to 1trillion comets orbiting the Sun!

Astronomical Unit Because distances in space are so large we use astronomical units (AU). An AU is the average distance from Earth to the Sun This is about 150 million km

What Keeps Earth Moving? NOTHING!!! Inertia states that an object in motion will stay in motion unless acted on by an outside force The Sun just keeps us on an orbital path instead of flying out into space

Revolution and Rotation The time it takes an object to travel once around the Sun is its period of revolution The time it takes an object to complete one rotation (around its axis) is its period of rotation

Planetary Orbit A planets orbit is an ellipse Inside the ellipse are 2 special points, each called a focus. These points determine the shape of the ellipse. The Sun is at one of the foci, the other is empty space. As a result, the distance between the planet and the Sun changes as the planet moves

Planetary Speeds The closer the planet is to the Sun, the faster it moves. Planets further from the Sun have longer periods of revolution. Jupiter takes 12 times longer than Earth to revolve around the Sun!