The Solar System
Solar System Formation
Your Parents’ Solar System
21st Century Solar System
The 21st Century Solar System Sun Terrestrial Planets Asteroid Belt Jovian Planets Kuiper Belt Oort Cloud
The Solar System: List of Ingredients Sun Jupiter Other planets Everything else Percent of total mass 99.8% 0.1% 0.05%
The Sun A middle-aged, average star: Shines because it is hot: Mostly Hydrogen & Helium 99.8% of the Solar System ~4.6 billion years old Shines because it is hot: Surface Temp ~6000 C Mostly Visible, UV & IR light Kept hot by nuclear fusion in its core: Builds Helium from Hydrogen fusion. Will shine for ~12 billion years
The Sun dominates the Solar System
Terrestrial Planets Mercury, Venus, Earth & Mars Rocky Planets: “Earth-Like” Rocky Planets Largest is Earth Only in the inner solar system (0.4 to 1.5 AU) Rocky Planets: Solid Surfaces Mostly Silicates and Iron High Density: (rock & metal) Earth, Venus, & Mars have atmospheres
The Terrestrial Planets Mercury (0.055 M) Venus (0.82 M) Earth (1 M) Mars (0.11 M)
The Jovian Planets Jupiter, Saturn, Uranus & Neptune Largest Planets: at least 15 times mass of Earth. Only in the outer solar system (5 to 30 AU) No solid surfaces (mostly atmosphere) Low density Gas Giants: (Jupiter & Saturn) Thick H/He atmosphere, liquid hydrogen mantle, ice core Ice Giants: (Uranus & Neptune) Ice/rock core & mantle, thin H/He atmosphere
The Jovian Planets Jupiter (318 M) Saturn (95 M) Uranus (15 M) Neptune (17 M)
Dwarf Planets Defined by the IAU in 2006 Dwarf Planets: Ceres: first of the Asteroids, discovered in 1801 Pluto: trans-Neptunian object discovered in 1930 Eris: trans-Neptunian object discovered in 2005 Haumea (trans-Neptunian, suspected) Makemake (trans-Neptunian, suspected)
Dwarf Planets
The Giant Moons Moon: any natural satellite orbiting a planet or dwarf planet Giant Moons: Earth: The Moon (Luna) Jupiter: Io, Europa, Ganymede, & Callisto Saturn: Titan Neptune: Triton Many smaller moons, both rocky & icy. Only Mercury & Venus have no moons.
The Giant Moons
Rhea Iapetus Titania Oberon Ceres Tethys Dione Ariel Umbriel Charon Pallas Vesta Hygeia Mimas Enceladus Miranda Proteus Io Mercury Europa Moon Triton Titan Ganymede Callisto Pluto
Kuiper Belt Class of icy bodies orbiting beyond Neptune. Examples: Found only in the outer Solar System (>30AU) Densities of 1.2 to 2 g/cc (mostly ices) Examples: Pluto & Eris (icy dwarf planets) Kuiper Belt Objects (30-50AU) Charon, Pluto’s large moon Sedna & Quaor: distant large icy bodies
Kuiper Belt
Oort Cloud Spherical cloud of comets. Extends out to almost 50,000 AU (1 light-year) May contain trillions of comets The outer edge is the farthest reach of the Sun’s gravitational pull. There are no confirmed observations – its existence is theoretical only.
Oort Cloud
The Leftovers (small bodies) Asteroids: Made of rock & metal (density 2-3 g/cc) Sizes: Few 100km to large boulders Most are found in the Main Belt (2.1-3.2 AU) Meteoroids: Bits of rock and metal Sizes: grains of sand to boulders Comets: Composite rock & ice “dirty snowballs” Longs tails of gas & dust are swept off them when they pass near the Sun.
Asteroids 951 Gaspra 243 Ida 253 Mathilde
Meteor burning up in the atmosphere.
Comet P/Halley Comet P/Wilt
Is Pluto a Planet? What to consider? Size? Shape? Orbit? What is it made of?
IAU Definition of a Planet In 2006, the International Astronomical Union (IAU) came up with the following definition of a planet: orbits the Sun has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape (i.e., it is spherical), has cleared the neighborhood around its orbit, is not a satellite
IAU Definition of a Dwarf Planet In 2006, the International Astronomical Union (IAU) came up with the following definition of a dwarf planet: orbits the Sun has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape (i.e., it is spherical), has not cleared the neighborhood around its orbit, is not a satellite