Download The Solar System

Joy of Science
Experience the evolution of the
Universe, Earth and Life
•  Review of last class
•  Introduction to the solar system
•  Contents of today’s lecture
•  Quiz time
Unless otherwise noted, all pictures are taken from wikipedia.org
Review 1
n  The presence of CMB radiation is good evidence for
A. the internal makeup of the Sun
B. the account of creation in Genesis
C. the steady-state universe
D. the big bang theory
Review 1
n  The presence of CMB radiation is a good evidence for
A. the internal makeup of the Sun
B. the account of creation in Genesis
C. the steady-state universe
D. the big bang theory
Review 2
n  The Milky Way, the galaxy within which we live, is
A. an irregular dwarf galaxy
B. a quasar galaxy
C. an elliptical galaxy
D. a spiral galaxy
Review 2
n  The Milky Way, the galaxy within which we live, is
A. an irregular dwarf galaxy
B. a quasar galaxy
C. an elliptical galaxy
D. a spiral galaxy
Review 3
n  A large assembly of stars together with gas, dust, and other materials
that is held together by the forces of mutual gravitational attraction is
called
A. a solar system
B. a planetary system
C. a galaxy
D. the cosmos
Review 3
n  A large assembly of stars together with gas, dust, and other materials
that is held together by the forces of mutual gravitational attraction is
called
A. a solar system
B. a planetary system
C. a galaxy
D. the cosmos
Review 4
n  According to the big bang theory of the origin of the universe
A. all galaxies in the universe are converging on one another
B. all galaxies in the universe are moving away from one another
C. the universe is presently in a steady-state configuration
D. new galaxies are constantly being formed in the space vacated
by present-day galaxies
Review 4
n  According to the big bang theory of the origin of the universe
A. all galaxies in the universe are converging on one another
B. all galaxies in the universe are moving away from one another
C. the universe is presently in a steady-state configuration
D. new galaxies are constantly being formed in the space vacated
by present-day galaxies
The Solar System
- Experience the evolution of the sun, planets
and moons
Today’s Keywords
solar system, terrestrial planets (Mercury, Venus,
Earth, Earth’s moon, Mars), Jovian planets
(Jupiter, Saturn, Uranus, Neptune), moons
Outline of today’s lecture
0. Introduction
1. Nebular Hypothesis – modern theory to explain how stars are born
from clouds of gases and dusts, applicable to
the solar system formation
2. Inner Solar System
3. Outer Solar System
4. All other objects
Introduction
n  Solar system: containing objects gravitationally bound to Sun
n  Sun, 8 planets, planets’ moons, asteroids, comets, meteors, and
planet-like objects e.g. Pluto
From library.thinkquest.org
Introduction
n  Solar system: containing objects gravitationally bound to Sun
n  Sun, 8 planets, planets’ moons, asteroids, comets, meteors, and
planet-like objects e.g. Pluto
n  Clues to the origin and evolution of the solar system
1. Planetary orbits
- all planets and their moons orbit in the same around the sun
- all orbits of planets and their larger moons on the same plane
- almost all planes and moons rotate on the same the direction
as planets orbit
n  2. Distribution of mass
- sun: the center, 99% of total mass
- planets: small rocky inner planets, gas giant outer planets
- moons: almost all planets have own moons
- asteroids: miniature plants, mainly between Mars and Jupiter
Nebular hypothesis – formation of
the solar system
n  Recall the birth of stars! The sun is the nearest star to us.
Recall!
Birth of Stars – all starts from
hydrogen burning stage
Stars live and die like everything else!
The birth of stars
n  All stars are born in clouds of gases and other debris (Nebulae)
n  Nebulae typically contain 99% of hydrogen and helium
n  A nebula collapses onto itself slowly due to gravity, and the
collapse causes to spin faster and faster (Imagine a kitchen sink
as gravity and water in the sink as a gaseous cloud – nebula )
n  The fast rotation makes the outer flat and the center dense
n  As more and more mass pours into the center the pressure and
temperature increase higher and higher
à Nuclear fusion starts!
è The birth of a star!!!
Nebular hypothesis – formation of
solar system
n  Recall the birth of stars! The sun is the nearest star to us.
n  The process of formation of solar system in Nebular hypothesis
- A nebula which is a cloud of gas and dust with 99% of hydrogen
and helium collapses onto itself slowly due to gravity
- The collapse causes to spin faster
- The fast rotation makes the outer flat and the center dense
- The dense core eventually become the Sun, the flat outer disk
eventually becomes planets and others
n  Consequences from the formation
àPlanets orbits lie close to the disk’s plane dude to the solar
system’s rapid rotation as the nebular cloud began to contract
àBy chance, matter collected in some regions more than elsewhere.
Stronger gravitational force accumulate more nearby matter
Credit: diagram of a solar nebula
late step in the formation of the
solar system
n  Light energy began to radiate out from the sun à temperature
differences began to develop in the disk à nearest planets were
warmed up, farther ones warmed only a little
è Inner and outer solar systems developed differently
n  Terrestrial planets – Mercury, Venus, Earth, and Mars- in the
inner solar system were formed from materials that could remain
solid at high temperature è small, rocky worlds
n  Jovian planets – Jupiter, Saturn, Uranus, and Neptune – in the
outer part are composed essentially of the material of the
original nebula è gas giants
Inner solar system
Outer solar system
Inner solar system
Mercury, Venus, Earth, Mars: Terrestrial planets
n  Mercury: smallest planet, nearest from Sun, too hot
n  Venus: Earth-like planet with rocky surface. Green house effect
(main composition of atmosphere is CO2, temperature ~ 500 C deg)
n  Mars: most likely to have harbored life
- water ice on the north pole
- possibility of existence of early life before it lost its atmosphere to
gravitational escape
- Martian missions especially by NASA for life detection and
sample return will be proceeded
Inner: nineplanets.org
Outer solar system
Jupiter, Saturn, Uranus, Neptune, (Pluto): Jovian planets
-  Compounds are liquid or solid forms of carbon dioxide, nitrogen,
and methane under the intense pressures in interiors
-  Compounds of atmosphere: mainly ?
n  Jupiter
- Gigantic gas planet: largest planet in the solar system
- Very fast rotational speed à outer atmosphere segregated into
several bands at different latitudes, resulting in turbulence and
storms along their interacting boundaries
- Great Red Spot: big storm resulted by turbulent atmosphere
- Galilean moons: Io, Europa, Ganymede, Gallisto
- A faint ring system
Outer solar system
n  Saturn
- Second largest planet, fast rotational speed
- Titan: largest moon of Saturn, size about Mercury, made mainly
of rock and water ice. A kind of museum of early Earth’s
chemical environment
- Rings: arrays of dozens of fine bands
n  Uranus
n  Neptune
n  Pluto: traditionally regarded as a planet, but now considered as a
dwarf-planet which is a member of objects in the Kuiper belt
Outer: nineplanets.org
Q:
JAXA’s recently completed mission?
Q:
JAXA’s recently completed mission?
A:
A spacecraft Hayabusa, formally MUSES-C, retuned a sample
from a small near-Earth asteroid named 25143 Itokawa to Earth
Asteroids, Comets and Meteors
n  Asteroids: small rocky miniature planets, found mostly in a
broad circular asteroid belt between Mars and Jupiter.
Occasionally large impacts on Earth
n  Comets: “dirty snowballs” consisting of chunks of water ice and
methane ice in solid, rocky materials or dirt in it
n  Meteors: ancient space debris in orbit around the Sun fall into
Earth’s atmosphere, and become visible by burning
à meteors (falling star)
Meteorite: fallen rock to Earth from space
Asteroid: nineplanets.org