Inventory of the Solar System - University of Oregonpages.uoregon.edu/phys600/Chp6a.pdf ·...
Transcript of Inventory of the Solar System - University of Oregonpages.uoregon.edu/phys600/Chp6a.pdf ·...
3. Interplanetary Debris
! Asteroids,
! Comets,
! Kuiper Belt and Oort Cloud
Chapter 6 Part A1. The Solar System
! Inventory of the Solar
System
! Planetary Orbits, Spins
Masses of Planets
! Densities of the Planets
2. Classes of Planets
! Terrestrial,
! Jovian,
! Major Moons
• Sun
• Planets
Terrestrial & Jovian
• Moons
• Over 162
Inventory of the Solar System
• Asteroids
–Small, rocky, minor planets. Most are located in the asteroid belt.
• Comets
–Small, icy bodies--Dirty Snowballs.
• Interplanetary gas and dust
• Solar Winds
There are eight "classical" planets
(Mercury thru Neptune, including Earth but not Pluto).
outer planets: Jupiter, Saturn,
Uranus, Neptune.
inner planets:
Mercury,
Venus, Earth
and Mars.
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.
Dwarf Planets
Planets orbit essentially in the same plane (Ecliptic)
Largest Orbital inclination are Mercury (7 degrees) and
Pluto(17 degrees)
Orbits
Outer PlanetsInner Planets
Orbits counter-clockwise
Orbits nearly circular
5.2 9.554 19.14 30.066 AU
.382 .723 1 1.524 AU
Astronomical Unit (AU)= Earth-Sun Distance or 150 million km! 1.5 108
km
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
Inner Planets Outer Planets
Sec 1
"The spin axes of most planets and moons are perpendicular to
the orbital plane (Exceptions: Venus,Uranus and Pluto).
Obliquity Rot Per (hrs)
Mercury 0.1° 1407.5
Venus 177.4° 5832.5
Earth 23.45° 23.9
Mars 25.19° 24.6
Sun ~ 300,000 times mass of Earth
Mass of Planets (units of Earth Masses}
Sec 1
Solar System MassSun 99.80%
Jupiter 0.10%
Comets 0.05%
Other 8 planets 0.04%
Total of Sun + Planets +
Comets = 99.99%
Size of the planets
Density• Density measures the “type” of matter.
Density = mass/volume (g/cm3)
• For a planet:
– From the diameter you can calculate volume.
– From the mass you can calculate the average density.
Density of water = 1.0 g/cm3 ;
Density of silicate rock = 3.0 g/cm3
Density of iron = 7.8 g/cm3
Sec 1
A denser object occupies less volume thanan equal mass of some less densesubstance
Terrestrial !5
Jovian !1 to 2
Density of
PlanetsTwo distinct groups of planets classifying by
composition(Density).
Dwarf
Jovian Planets:Jupiter,
Saturn, Uranus, Neptune
Sec 2
Jovian or gas planets:
!composed primarily of
hydrogen and helium
! have low densities,
! rapid rotation,
!deep atmospheres,
! rings and lots of satellites
Terrestrial Planets:
Mercury Venus Earth Mars
! 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
Saturn has one
large satellite Titan
with its dense and
organic-rich
atmosphere
together with
numerous much
smaller satellites.
Jupiter's four
Galilean satellites
are each roughly
similar in size.
They include
volcanic Io and
Europa with its
believed
subsurface ocean.
• 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.
Asteroid Belt
“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.
Comets 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.
Oort cloud Extends to 1/3 of way to nearest star. Orbit at
any inclination and direction.
End of Chapter 6a
Go to Chapter 6b