Learning target: I will be able to distinguish the difference between the parts of our solar system Warm –Up Write the planets in order

Introduction to the solar system Chapter 4.1

Changing views of our solar system Earth at the center of the universe Everything was in spheres rotating around Earth ~ 150 AD Ptolemy published a model of the solar system

Changing views of our solar system The Sun at the center of the universe ~1500 years after Ptolemy Copernicus proposed Sun in the center of the universe Model wasn’t published till he died Wasn’t until Galileo created his telescope Proposed the planets orbit the sun like the moons of Jupiter orbited the planet

Planets and their motion Solar System: the sun and all the objects that are held together by the suns gravity 8 planets, 5 dwarf planets, over 165 moons, many asteroids and other objects

What is and is not a planet Pluto controversy Planet was discovered in 1930 later to find that it wasn’t like the other 8 planets They were using older telescopes so they didn’t have the ability to see Pluto and its moon as two separate things Astronomers also discovered many objects like Pluto ( icy and rocky) They had to decide…. What makes a planet

What makes a planet a planet A planet must be the following Orbit a star Be big enough that its own gravity causes it to be round Be small enough it isn’t a star itself Have cleared that area of its orbit Dwarf Planet If the first three listed above are true

The size and shape of orbits The farther from the sun the greater the one planets orbit is to the next planet

The size and shape of orbits Planets are held in their orbits by gravity Gravity depends on the mass of the object and how far apart the objects are from each other

Extrasolar planets Since early 1900’s we have discovered other solar systems exoplanets When a planet orbits a star other than our Sun Signs Slight motion in the star due to the planets gravitation pull Partial dimming of star’s light as the planet passes in front