Joy of Science Experience the evolution of the Universe, Earth and Life

Joy of Science Experience the evolution of the Universe, Earth and Life Review Introduction Main contents Quiz Unless otherwise noted, all pictures are taken from wikipedia.org

Review 1 The presence of Cosmic Microwave Background (CMB) radiation is good evidence for 1. the internal makeup of the Sun 2. the account of creation in Genesis 3. the steady-state universe 4. the big bang theory

Review 2 The Milky Way, the galaxy within which we live, is 1. an irregular dwarf galaxy 2. a quasar galaxy 3. an elliptical galaxy 4. a spiral galaxy

Review 3 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 1. a solar system 2. a planetary system 3. a galaxy 4. the cosmos

Review 4 According to the big bang theory of the origin of the universe 1. all galaxies in the universe are converging on one another 2. all galaxies in the universe are moving away from one another 3. the universe is presently in a steady-state configuration 4. new galaxies are constantly being formed in the space vacated by present-day galaxies

May 11, 2012 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

Contents of today s lecture 1. Introduction 2. Nebular Hypothesis modern theory to explain how 3. Inner Solar System 4. Outer Solar System 5. All other objects stars are born from clouds of gases and dusts, applicable to the solar system formation

1. Introduction Introduction Solar system: containing objects gravitationally bound to Sun Sun, 8 planets, planets moons, asteroids, comets, meteors, and planet-like objects e.g. Pluto

1. Introduction From library.thinkquest.org

1. Introduction Introduction Clues to the origin and evolution of the solar system 1) Planetary orbits - All planets and their moons orbit in the same direction around the sun, and the direction is the same as that of sun s rotation - All orbits of planets and their larger moons on the same plane - Almost all planets and moons rotate on the same the direction as planets orbit 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 planets, mainly between Mars and Jupiter

Nebular hypothesis formation of the solar system 2. Nebular hypothesis Recall the birth of stars. The sun is the nearest star to us!

2. Nebular hypothesis Nebular hypothesis formation of the solar system 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

2. Nebular hypothesis Nebular hypothesis formation of the solar system Consequences from the formation à Planets orbits lie close to the disk s plane dud 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

Birth of Stars all starts from Stars live and die like everything else! The birth of stars hydrogen burning stage All stars are born in clouds of gases and other debris (Nebulae) Nebulae typically contain 99% of hydrogen and helium 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 ) The fast rotation makes the outer flat and the center dense 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!

Credit: diagram of a solar nebula

Late step in the formation of the solar system 2. Nebular hypothesis 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 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 Jovian planets Jupiter, Saturn, Uranus, and Neptune in the outer part are composed essentially of the material of the original nebula è gas giants

2. Nebular hypothesis Inner solar system Outer solar system

3. Inner solar system Inner solar system Mercury, Venus, Earth, Mars: Terrestrial planets (Earth-like)

3. Inner solar system Inner solar system Mercury, Venus, Earth, Mars: Terrestrial planets Mercury: smallest planet, nearest from Sun, too hot Venus: Earth-like planet with rocky surface. Green house effect (main composition of atmosphere is CO 2, temperature ~ 500 C deg) 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 3. Inner solar system

4. outer solar system Outer solar system Jupiter, Saturn, Uranus, Neptune, (Pluto): Jovian planets (Jupiter-like) - Compounds are liquid or solid forms of carbon dioxide, nitrogen, and methane under the intense pressures in interiors - Compounds of atmosphere: mainly?

4. outer solar system Outer solar system 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, Callisto - A faint ring system

4. Outer solar system Jupiter

4. Outer solar system Satern

4. Outer solar system Outer solar system 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 Uranus Neptune Pluto: traditionally regarded as a planet, but now considered as a dwarf-planet which is a member of objects in the Kuiper belt (leftover comet-like objects from the formation of solar system)

Outer: nineplanets.org 4. Outer solar system

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

4. Other objects Asteroids, Comets and Meteors Asteroids: small rocky miniature planets, found mostly in a broad circular asteroid belt between Mars and Jupiter. Occasionally large impacts on Earth Comets: dirty snowballs consisting of chunks of water ice and methane ice in solid, rocky materials or dirt in it 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

Comet Meteor crater in Arizona: 1200-meter-wide formed by a small car size meteorite meteorite

Today s group discussion topic: Lift-off for private space travel dream? http://www.bbc.co.uk/news/science-environment-13335687

Next class is on The Earth Chapter 13: The restless Earth