Transcript File - CVHS Chicklas

Solar System Formation
Your Parents’ Solar System
st
21
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
Ingredient
Sun
Jupiter
Other planets
Everything else
Percent of total mass
99.8%
0.1%
0.05%
0.05%
The Sun
• A middle-aged, average star:
– 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
– “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
Venus
(0.055 M) (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 Neptune
(15 M) (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
Mimas
Mercury
Iapetus
Miranda
Proteus
Tethys
Dione
Umbriel
Europa
Moon
Pallas
Ariel
Io
Hygeia
Triton
Titan
Ganymede
Vesta
Oberon
Callisto
Ceres
Rhea
Titania
Enceladus
Pluto
Charon
Kuiper Belt
• Class of icy bodies orbiting beyond Neptune.
– 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
253 Mathilde
951 Gaspra
243 Ida
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