Relative Size of Sun and Planets Solar System - Outline Relative Size of Sun and Planets Sun contains 99.9% of the mass of the solar system

3.5 Billion to One Scale Model Mars Earth Venus Mercury

3.5 Billion to One Scale Model Uranus Saturn Neptune Jupiter Pluto Mars

3.5 Billion to One Scale Model Sun Nearest Star Proxima Centauri

Q. 24: Why Isn’t Pluto a Planet? The Planets August 24, 2006: IAU defines a planet Goes around a star Is big enough to be round Is much bigger than all other things in its neighborhood combined Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune My Very Educated Mother Just Served Us Nachos A dwarf planet satisfies 1 and 2, but not 3 Pluto A small solar system body satisfies only 1 Q. 24: Why Isn’t Pluto a Planet?

The Planets – Relative Sizes Jupiter contains most of the mass of the planets

The Planets – Categorizing Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Terrestrial Planets Rock and metal, some atmosphere Few moons Bigger than Moon, Smaller than Earth Gas giants Metal, rock, ice, thick atmosphere Lots of moons! Bigger than Earth Rings!

The Terrestrial Planets Mercury Mars Earth and Moon Venus

Mercury Covered in craters Looks like the Moon No large dark areas (maria)

Venus Featureless ball, covered in clouds (in visible) Tan color

Earth and Moon Water Clouds Craters Dark maria

Mars Reddish tint Interesting surface Polar caps

Jovian Planets / Gas Giants Uranus Jupiter Neptune Saturn Earth (for comparison)

Jupiter Striped appearance Complicated clouds/storms

Jupiter’s Biggest Moons Europa Cracked, Icy Surface Io Mottled, Colorful appearance Ganymede Icy Surface, Dark and Light Regions Callisto

Saturn Very dramatic rings

Orange featureless ball Saturn’s Moons Enceladus Iapetus Dark and light regions Titan Orange featureless ball

Uranus and Miranda Miranda Unusual markings Uranus Almost featureless blue-green ball

Neptune and Triton Triton Complicated, Varied Terrain Neptune Blueish ball with small white clouds

The Kuiper Belt and Oort Cloud Eris and Dysnomia Pluto and Charon

Do you need a description? Comets Comet Halley Do you need a description?

The Asteroid Belt 1 Ceres 4 Vesta 461 Gaspra

Formation of the Solar System Outline Molecular Clouds Contraction - spin Protostar and Protoplanetary Disk Condensation Planetismals Planets Primary atmospheres Stellar winds vs. atmospheres Secondary atmospheres Cratering

Q. 25: Effects of Contraction of Molecular Clouds Huge, cool, relatively dense clouds of gas and dust Gravity causes them to begin to contract Clumps begin forming – destined to become stellar systems They inevitably have some rotation Composition 98% hydrogen (H2) and helium (He) 1.4% hydrogen containing molecules Water (H20), Methane (CH4), Ammonia (NH3) Collectively known as “ices” 0.6% rock and metal Q. 25: Effects of Contraction of Molecular Clouds

Molecular Clouds – Eagle Nebula

Molecular Clouds

Molecular Clouds – Keyhole and Orion

Molecular Clouds

Molecular Clouds – Horsehead Nebula

Gravity and Contraction Much of the gas is pulled to the center, where it is stopped by rising pressure Gravity vs. pressure = sphere A protostar The rest is stopped by rotation Gravity vs. rotation = disk The protoplanetary disk

Protostar / Protoplanetary Disk Grows

Protoplanetary Disks

Protoplanetary Disks

Protoplanetary Disk – Artist’s Rendition

Condensation As the cloud shrunk molecules started finding each other If cold enough, they could stick together Proto-Sun created heat – hotter for the inner regions Most of the region was cool enough to have rock and metal begin to form dust grains Vaporizes only around 1000+ K Beyond the “frost line” there were ices mixed in Ices vaporize around 150 K Beyond a few AU it was cool enough to form ices Nowhere cold enough for hydrogen or helium to condense