#5 Introduction to the Solar System

Just one star Solar means “sun” so solar system = sun system Not studying galaxies (billions of stars) or star clusters (millions of stars) yet, only our own solar system. Solar means “sun” so solar system = sun system Sun is a star, and is our only one!

How to measure something so large? The distance between stars (and galaxies) is HUGE so we measure it in light years. Light Years is the distance light will travel in a year **very important**: a light year is not a time, but a distance!

Astronomical Units Planets in our solar system are closer together, so we can use AU (Astronomical units) 1 AU=Average distance between the Earth and the sun (lazy scientists) Ex) Mercury is closer to sun (.39 AU) Ex) Pluto is further from sun (39.5 AU)

The Planets Now have 8 planets orbiting the Sun Orbits are elliptical An ellipse is a shape that can be thought of as a "stretched out" circle or an oval

Two major planet groups The planets are divided into two major groups 1. Terrestrial Planets (Inner Planets) 2. Gas Giants (Outer Planets) These two groups are separated in the middle by the asteroid belt

Gas Giants Asteroid Belt Inner Planets

Terrestrial Planets Inner Planets (closest to the sun) Mercury, Venus, Earth, Mars “Terrestrial” = “Land” Rocky (dirt-like and metal materials) Small Dense Few moons No Rings

Mercury Venus Earth Mars

Terrestrial Planets Mercury The Speediest Planet- Travels at 29.7 miles/sec. Venus The Twin Planet- roughly the same size as Earth and visible from Earth without a telescope Earth The Home Planet - only planet known to have an atmosphere that sustains life Mars The Red Planet - an iron surface is blown around by storms

The Gas Giants Outer Planets (Farthest from sun) Jupiter, Saturn, Uranus, Neptune Made of gas and liquid HUGE Low densities (Saturn floats in water) Lots of moons All of them have rings

The Gas Giants Jupiter The Giant Planet- All the other planets could be squeezed inside of it! Saturn The Ringed Planet- has the most (and the largest) rings Uranus The Tilted Planet- orbits on its side Neptune The Windy Planet- fiercest winds blowing up to 1400 mi/hr. Blue color, Named for the Roman God of the Sea

What about poor Pluto? Now considered a dwarf planet 2nd largest dwarf planet we know of Eris is bigger, Ceres is another Mass is about 1/5 that of our moon Made of Ice and Rock (Very Cold) Orbit is highly elliptical and sometimes dips into Neptune’s orbit

The Dwarf Planets

Here’s our solar system........

So putting it all together.....