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.

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!!!

Recall!

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 àPlanets orbits lie close to the disk’s plane dude to the solar system’s rapid rotation as the nebular cloud began to contract àBy 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