Download Inventory of the Solar System

Chapter 6 Part A
Inventory of the Solar System
1. The Solar System
! Inventory of the Solar
System
! Planetary Orbits, Spins
Masses of Planets
! Densities of the Planets
2. Classes of Planets
•
•
Sun
Planets
Terrestrial & Jovian
•
Moons
•
Over 162
! Terrestrial,
! Jovian,
!
Major Moons
3. Interplanetary Debris
!
Asteroids,
!
Comets,
!
Kuiper Belt and Oort Cloud
There are eight "classical" planets
(Mercury thru Neptune, including Earth but not Pluto).
inner planets:
Mercury,
Venus, Earth
and Mars.
outer planets: Jupiter, Saturn,
Uranus, Neptune.
Dwarf Planets
Planets, by the new IAU definition, must be in orbit around the sun, be
nearly spherical, and must have cleared the neighborhood around their
orbits.
• Asteroids
–Small, rocky, minor planets. Most are located in the asteroid belt.
• Comets
–Small, icy bodies--Dirty Snowballs.
• Interplanetary gas and dust
• Solar Winds
Planets orbit essentially in the same plane (Ecliptic)
Largest Orbital inclination are Mercury (7 degrees) and
Pluto(17 degrees)
Inner Planets
Outer Planets
Orbits
Inner Planets
Orbits counter-clockwise
Orbits nearly circular
Astronomical Unit (AU)= Earth-Sun Distance or 150 million km! 1.5 108
km
.382 .723 1 1.524 AU
5.2
9.554
19.14
30.066 AU
Obliquity
Mercury 0.1°
Venus
177.4°
Earth
23.45°
Mars
25.19°
Rot Per (hrs)
1407.5
5832.5
23.9
24.6
Outer Planets
Obliquity Rot Per (hrs
Jupiter 3.12°
9.925
Saturn 26.73°
10.656
Uranus 97.86°
17.24
Neptune 29.56°
16.11
Pluto 119.6
153.29
"The spin axes of most planets and moons are perpendicular to
the orbital plane (Exceptions: Venus,Uranus and Pluto).
Sec 1
Mass of Planets (units of Earth Masses}
Size of the planets
Sun ~ 300,000 times mass of Earth
Solar System Mass
Sun
99.80%
Jupiter
0.10%
Comets
0.05%
Other 8 planets 0.04%
Total of Sun + Planets +
Comets = 99.99%
Sec 1
Density
Density of
Planets
• Density measures the “type” of matter.
Two distinct groups of planets classifying by
composition(Density).
Density = mass/volume (g/cm3)
• For a planet:
Terrestrial !5
– From the diameter you can calculate volume.
– From the mass you can calculate the average density.
Density of water = 1.0 g/cm3 ;
Dwarf
Density of silicate rock = 3.0 g/cm3
Density of iron = 7.8 g/cm3
Jovian !1 to 2
A denser object occupies less volume than
an equal mass of some less dense
substance
Sec 1
Jovian Planets:Jupiter,
Saturn, Uranus, Neptune
Terrestrial Planets:
Mercury
Venus
Earth
Mars
Jovian or gas planets:
!composed primarily of
hydrogen and helium
! have low densities,
! rapid rotation,
!deep atmospheres,
! rings and lots of satellites
Sec 2
! small objects close to Sun
!Rotation rate: Earth and
Mars ~ 24 hrs, Mercury ~ 2
months, Venus ~ 8 months
!Few moons: Earth - 1, Mars 2 Mercury and Venus - 0
! solid surfaces that record their
history in craters, mountains, and
volcanoes.
!High density: mostly rock and metal
composition
!Atmospheres: near vacuum to dense
hot gas
Major Moons
Asteroid Belt
Jupiter's four
Galilean satellites
are each roughly
similar in size.
They include
volcanic Io and
Europa with its
believed
subsurface ocean.
Saturn has one
large satellite Titan
with its dense and
organic-rich
atmosphere
together with
numerous much
smaller satellites.
Comets
“Dirty Snow Balls”
Composed largely of ices--- water ice, ammonia ice, methane ice--mixed with dust Inhabit two distinct regions of space:
Kuiper Belt and Oort cloud.
• Relatively small, rocky objects that revolve around the Sun.
– Much smaller than planets.
– Largest known: Ceres
• 940 km diameter (480 miles)
• 1/10,000 mass of Earth
• Most move in orbits between Mars and Jupiter.
• remnants of objects that didn’t form a planets.
Kuiper Belt
Kuiper belt, an icy belt of comet-like bodies extending beyond Neptune's
orbit (30-100 AU ). Kuiper belt Comets orbit in same direction as planets
and in same general plane.
End of Chapter 6a
Oort cloud Extends to 1/3 of way to nearest star. Orbit at
any inclination and direction.
Go to Chapter 6b