SOLAR SYSTEM

Planet: a celestial body that orbits one or more stars

Solar system: a group of planets circling one or more stars

Revolution: one “turn” around the sun

Rotation: one “spin” of a planet Axis: the centre line a planet spins

around

The Sun

The centre of the solar system The sun contains more than 99% of

the mass of its solar system Our sun is mostly made of hydrogen

gas Our sun is so large it would take 110

earths lined up to reach the sun’s width

Features of the sun

Solar Wind

Sometimes energetic gases burst on the surface of the sun sending a wave of high energy particles past earth

This wave is called solar wind When these particles come into

contact with the atmosphere at the poles they collide with particle there and create the northern lights

Moons

An object that orbits around a planet is known as a “satellite”

One of our natural satellites is our moon

Asteroids Smaller than planets or moons,

asteroids are chunks of rock orbiting our sun (and other suns)

They are believed to be the left over remains from the formation of the solar system

They range in size from a grain of sand to 1000 km wide

Comets

Made of ice, rock and gas (though mostly rock)

They hurtle through space at high speeds and leave a trail of gas and dust behind them

Trans-Neptunian Objects Anything

orbiting our sun way out past the planet Neptune are known as Trans-Neptunian objects

Often called “Dwarf planets”

Kuiper belt and Oort cloud Two possible sources of comets Kuiper belt is a flat disk of millions of

small bodies orbiting the sun Oort cloud is a spherical cloud of

small icy fragments orbiting at the farthest reaches of the sun’s gravity