Transcript The Solar System - Otto

Chapter 4
The Solar System
Comet Tempel
Chapter overview
• Solar system inhabitants
• Solar system formation
• Extrasolar planets
Solar system inhabitants
• Sun
• Planets
• Moons
• Asteroids
• Comets
• Meteoroids
• Kuiper Belt Objects
Figure 4.1
Solar System
Planets
•
•
•
•
•
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Orbital size
Orbital period
Mass
Radius
Moons
Density (water density is 1000 kg/m3)
Table 4-1
Properties of Some Solar System Objects
Planetary orbits
• Lie in same plane (ecliptic plane)
• Mercury and Pluto are slight exceptions
• Orbit around sun in same direction
Figure 4.2
Planetary Alignment
Terrestrial planets
• Mercury
• Venus
• Earth
• Mars
Jovian planets
• Jupiter
• Saturn
• Uranus
• Neptune
• Memory aid: S-U-N
Figure 4.3 - Sun and Planets
Table 4.2 - Comparison Between the
Terrestrial and Jovian Planets
Table 4-2
Comparison Between the Terrestrial and Jovian Planets
Other planet?
• Pluto
• As of late 2006, demoted from a planet
Interplanetary matter
• Asteroids
• Comets
• Meteoroids
Figure 4.4
Inner Solar
System
Asteroids
• Asteroid belt
• Between orbits of Mars and Jupiter
• Noticeably elliptical orbits
• Trojan asteroids
• Earth crossing asteroids
• Up to 1000 km in size
Figure 4.5
Asteroids, from
Earth
Figure 4.6
Asteroids, Close-up
a) Gaspra
b) Ida with Dactyl
c) Mathilde
Asteroid types
• Carbonaceous
• Dark, water ice and organics (carbon)
• Silicate
• Reflective, more rocky
• Inner portion of asteroid belt
Figure 4.7
Asteroid Eros
Discovery 4-1a
What Killed the Dinosaurs?
Discovery 4-1b
What Killed the Dinosaurs?
Figure 4.8
Halley’s Comet
Comets
• Nucleus
• Coma (dust and evaporated gas)
• Hydrogen envelope
• Ion tail
• Dust tail
• Tails directed away from sun
Figure 4.9
Comet Tails - Comet Hale-Bopp 1997
Figure 4.10
Comet Trajectory
Figure 4.11
Halley’s Comet Close-up
from Giotto spacecraft in 1986
Figure 4.12
a) Comet Wild-2
from Spacecraft
Stardust
b) aerogel for comet
dust
Short period comet orbits
• Short period (< 200 years)
• Kuiper belt (beyond Neptune)
• 30 to 100 AU from sun
• Roughly circular orbits, in ecliptic plane
• Occasionally kicked into inner solar system
• About 900 Kuiper belt objects (KBO) known
• Some KBO’s larger than Pluto
Long period comet orbits
• Long period (> 200 years)
• Oort cloud
• Up to 100,000 AU diameter
• Random orbital orientation
• Occasionally kicked into inner solar system
Figure 4.13
Comet Reservoirs
Meteor terminology
• Meteoroid (chunk of space debris)
• Meteor (streak of light in sky)
• Meteorite (piece of meteoroid that falls to
ground)
• Micrometeoroids
• Meteoroid swarm or shower (cometary
debris)
Figure 4.14
Meteor Trails
Figure 4.15
Meteor Showers
Table 4.3 Some Prominent Meteor Showers
Table 4-3
Some Prominent Meteor Showers
Figure 4.16
Radiant
Figure 4.16 Analogy
Railroad Tracks Converging
Meteor craters on earth
• About 100 craters over 100 m in
diameter
• Others heavily eroded by weather or
geological activity
Figure 4.17 - Barringer Crater, Arizona
Figure 4.18
Manicouagan
Reservoir,
Quebec
Figure 4.19
Tunguska Debris (Siberia, 1908)
Meteorite types
• Rocky silicate
• Iron with some nickel
• Carbonaceous
• 4.4 to 4.6 billion years old
Figure 4.20 - Meteorite Samples
(a) rocky or stony (silicate) (b) iron and some nickel
Model of Solar System formation must explain
1. Each planet isolated
2. Planet orbits nearly circular
3. Planet orbits nearly lie in a plane
4. Planets orbit sun in same direction sun rotates
5. Most planets rotate in same direction sun rotates
6. Most moons revolve in direction planet rotates
7. Terrestrial vs. Jovian planets
8. Asteroids are old and are unlike planets
9. Kuiper belt objects
10. Oort cloud comets
Figure 4.21
Angular Momentum
Figure 4.22
Beta Pictoris
More Precisely 4-1
The Concept of Angular Momentum
More Precisely 4-1b
Conservation of Angular Momentum
Figure 4.23 - Dark Cloud containing interstellar dust and gas
Formation of solar system
• Nebular contraction
• Spinning material flattens into pancake as it
contracts
• Condensation of interstellar dust
• Accretion
• Millions of planetesimals
• Protoplanets
• Fragmentation
• Protosun
Figure 4.24
Solar System
Formation
Figure 4.25
Newborn Solar Systems?
Jovian planets
• Outer planets grew rapidly
• Gravitationally attracted gas from solar nebula
• Or could have started as gravitational
instabilities in solar nebula
Figure 4.26
Jovian
Condensation
Figure 4.27
Temperature in the
Early Solar Nebula
Figure 4.28
Planetesimal Ejection
Figure 4.29
Extrasolar
Planet
Extrasolar planets
• Indirectly detected by motion of star
• Large Jupiter-like planets in small orbits
• Selection effect
• Only detect largest and closest to the star
• Is our solar system unique?
Figure 4.30
Planets Revealed
Figure 4.31
An Extrasolar Transit
Figure 4.32
Extrasolar Orbits
Figure 4.33
Sinking Planet