Planets

What we know… There are eight planets in our solar system: –Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. The planets are arranged into inner and outer planets based on their distances from the sun.

Brain Pop Our Solar System: pace/solarsystem/ pace/solarsystem/

Pluto; Not a Planet anymore… Pluto was once considered to be a planet in our solar system. Due to advances in technology Astronomers located other objects further out than the orbit of Pluto that were the same size, or even bigger. This forced the IAU to reconsider the criteria required for planet status.

What makes a Planet a Planet? A planet must meet the following 3 requirements in order to qualify as a planet: –It needs to be in orbit around the Sun –It needs to have enough gravity to pull itself into a spherical shape –It needs to have “cleared the neighborhood” of its orbit

What does “cleared the neighbourhood” mean? As planets form, they become the dominant gravitational body in their orbit in the Solar System. As they interact with other, smaller objects, they either consume them, or sling them away with their gravity.

Poor Pluto… With the discovery of other, larger, objects in it’s orbit Pluto was reconsidered and became known as a dwarf planet. pace/pluto/ pace/pluto/

What Else is Out There? Asteroids: Rocks floating in space. These can range in size from 1m to hundreds of km. Thought to be the building blocks of our solar system, many share characteristics of planets. Some asteroids cross the path of Earth and pose a potential collision hazard. ds/ ds/

Comets Comets are made up of ice and dust and orbit the sun at large distances. At specific times certain comets are visible to the human eye, the most famous being Halley’s comet. Ihttp:// I

Meteors As rocks and fragments from space enter to the Earth’s atmosphere friction causes these particles to burn up. If the fragment is large enough it sometimes generates enough light to be visible, often be called “shooting stars”, these are called Meteors.

Meteorites When meteors are large enough or tough enough where a part of it survives to strike the Earth they are called Meteorites. DDRlAhttp:// DDRlA

Questions 1.Explain how the inner planets are different from the outer planets. 2.In what way is Uranus different from the other planets? 3.Explain why Pluto is not considered a planet anymore. 4.Explain how comets, asteroids and meteors are different. 5.Neptune is sometimes farther from the sun than Pluto. Explain why this happens.