Formation of the Solar System

Week 5(Welcome back from Spring Break)

Quick overview of the Solar System

• Space School: http://www.youtube.com/watch?v=mtKNH2Y2OJM&feature=related

Theories of How the Solar System Formed

Target 1:• Summarize the major features that a theory of solar system

origins has to explain.

All theory's of how the solar system formed must explain observations of composition, motion, and organization of the objects in the solar system.

YouTube Video:Astropedia

http://www.youtube.com/watch?v=l82OYfeDWqY&feature=bf_prev&list=PLA021BE54103940FE&lf=plpp_video

TERRESTRIAL vs GIANT PLANETS

The inner planets are smaller and denser than the outer planets, and are made of silicates and metals. In contrast, the outer planets are dominated by hydrogen and have many satellites that are rich in water ice and other volatiles.

DIFFERENTIATION!!!!

PROGRADE ROTATION

All planets move around the Sun in the same direction that the Sun rotates and close to the equatorial plane of the Sun.

Visit this animation to observe the motions of the objects in the solar system.

http://janus.astro.umd.edu/javadir/orbits/ssv.html

Angular Momentum

Mass and Angular Momentum• Although the Sun has

99.98% of the mass in the solar system, the planets have 99.7% of the system’s angular momentum.

This means that most of the “spin” in the solar system comes from the planets!

Definition• Angular Momentum:

is a vector quantity that can be used to describe the overall state of a physical system.

• Linear Momentum:p = mv

Angular Momentum: Try this at home!

Angular Momentum, L

L = mvrL = angular momentum

m = massv = velocityr = radius

Which one of these variable changed in your spinning seat experiment?

Angular Momentum of a system is Conserved in the Universe!

One of Brian Boitano’s crowd-pleasing skating moves involves initiating a spin with his arms extended and then moving his arms closer to his body. As he does so, he spins at a faster and faster rate. Which of the following laws best explains this phenomenon?

(A) Conservation of Mechanical Energy (B) Conservation of Angular Momentum (C) Conservation of Linear Momentum (D) Newton’s First Law (E) Newton’s Second Law

Angular Momentum is Conserved

Professor Brian Cox provides a preview of the winning theory of the formation of the solar systems and how angular momentum plays an important role:

http://www.youtube.com/watch?v=zzGxbFVOX1A&feature=related

RETROGRADE PLANETS

Despite the general regularity of planetary orbital spin motion, Venus, Uranus and Pluto all spin in a retrograde direction.

Read Handout: Retrograde Rotation

Tilt of Planets on their AxesWhy do the planets have tilts?

• The asteroids have compositions intermediate between the rock & metal rich inner planets and the volatile-rich outer solar system, and are located between the orbits of Mars and Jupiter.

• The oldest and most primitive meteorites contain grains of compounds that are expected to have formed in a cooling cloud of cosmic abundance at temperatures of a few hundred degrees.

• The oldest rock age recorded in the solar system is 4.5 billion years old.

COMETS

Comets, like the surface of some outer planet satellites, appear to be composed primarily of water ice, with significant quantities of trapped or frozen gases like carbon dioxide, plus silicate dust.

Volatiles

Volatile compounds (such as water) must have reached the inner planets in spite of the fact that he bulk composition of these bodies suggests formation at temperatures too high for volatiles to form solid grains

Irregular Satellites

All the giant planets have systems of regular satellites orbiting in their equatorial planes, rather like miniature versions of the solar system.

Regular Satellites: Uranus

Except Uranus, the giant planets have one or more irregular satellite that have an orbit that is either retrograde or have high inclinations or eccentricities.

• What is the solar system made of?• Where did that material come from?• Why is the solar system rotating?• How did the planets form?• Why are there some terrestrial planets and some

gaseous or icy? And why are they where they are?

• Why do some planets have moons?• How old is the solar system?

The Condensation Theory

• The most widely accepted theory of the formation of our own solar system and other planetary systems.

Reading: The Condensation Theory - Nebular Contraction

http://lifeng.lamost.org/courses/astrotoday/CHAISSON/AT315/HTML/AT31502.HTM

OverviewCollapse of a nebula

(a) Conservation of angular momentum demands that a contracting, rotating cloud

(a) must spin faster as its size decreases.

(b) Eventually, the primitive solar system came to resemble a giant pancake. The large blob at the center would ultimately become the Sun.

Condensation and Accretion

Reading: Differentiation in the Solar System – The Role of Heathttp://lifeng.lamost.org/courses/astrotoday/CHAISSON/AT315/HTML/AT31503.HTM

Age of the Solar System

• http://www.youtube.com/watch?v=UcaZfWaNR64&feature=fvsr

What will the JWST tell us about the Solar System?

Fun Friday

The History Channel - The Universe:How the Solar System was Madehttp://www.youtube.com/watch?v=Wj-OWGHYxLg&feature=related

Learning Targets• Summarize the major features that a theory of solar system origins has to

explain. • Outline the process by which planets form as natural by-products of star

formation. • Explain the role played by dust in the currently accepted model of solar

system formation. • Account for the differences between the terrestrial and the jovian planets. • Discuss the role of collisions in determining specific characteristics of the

solar system. • Explain the angular momentum problem and discuss some proposed

solutions. • Discuss the role of meteorites and radioactive dating to determine the

current age of the solar system.

Review with Questions

• http://lifeng.lamost.org/courses/astrotoday/CHAISSON/AT315/HTML/AT315EOC.HTM

• Reference:http://lifeng.lamost.org/courses/astrotoday/CHAISSON/AT315/HTML/AT31500.HTM