Part 1: The evolution of the solar system

Origin of the Universe Lesson 1

Introduction The universe includes all of space and all of the known matter and energy. This includes millions of galaxies and the stars within. Galaxies can contain up to million stars!! Where did all this come from???

Introduction Scientist currently believe that the Universe is expanding away from a central group of galaxies. They believe this began billion years ago (BYA).

Big Bang Theory This theory states: In a huge explosion, all matter and energy was distributed throughout the Universe. As time passed, temperatures decreased and galaxies started forming due to condensation (the act of reducing a gas or vapour to liquid form). As time passes, the universe will continue to expand which means objects in space are not in a fixed place, they are moving.

Big Bang Theory This theory is a ‘closed model’. What this means is that all the matter currently expanding will eventually collapse back onto itself due to gravity. (like a stretched rubber band) As a result, there will be another huge explosion because of the collisions of objects and the process will start again. VideoVideo

Flat Universe Theory This theory also states that the Universe began with a huge explosion. This theory however states that matter will continue moving outward and not collapse back onto itself. The universe will continue to expand.

Steady State Theory This theory is quite different from the other two. It states that the Universe had no origin and that it’s always existed. It’s widely unaccepted because it states that new matter is being created to explain the expansion of the universe. This goes against many laws of physics.

Galaxies Galaxies are the largest structures in the Universe. They are made from stars, gas and dust and are named according to shape. What galaxy do we live in?

Galaxies Looking at the night sky, you can see the Milky Way. It’s the part of the sky most densely populated by bright objects. This band of stars is the disc of our spiral galaxy.

Galaxies Spiral Galaxies: Spiral in shape, look like a disk if viewed from the side. Most common galaxy in the Universe Milky Way is a spiral galaxy

Galaxies Elliptical Galaxies: Very small Do not give off as much light as spiral galaxies Have an elliptical shape

Galaxies Irregular Galaxies: Asymmetrical Not common

Galaxies Barred Spiral Galaxy: Similar to spiral Have wings

Solar System A solar system lies within a galaxy and is composed of planets, asteroids, comets and other objects that orbit a star or stars.

Solar System Planet: A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity.

Solar System Asteroid: Relatively small objects made up of solid fragments of matter that orbit the sun mainly in between Mars and Jupiter.

Solar System Meteorite: Solid fragments of asteroids

Solar System Comet: A small object that orbits the sun made up of ice and dust.

Homework Read pages 6-10 Prelim Spotlight Text Update vocab list Complete To Think About Set 1 and 2 pg 10

Creation of our solar system Lesson 2

Solar System The creation of Earth is interlinked with the creation of our solar system. They began forming at the same time as a result of the same forces.

The Formation of our Solar System A large cloud of dust and gas (nebula) began to collapse onto itself. It is believed that this collapse may have been triggered by a shockwave from a supernova nearby. VideoVideo Nebula Supernova

The Formation of our Solar System As the pressure caused by the collapse increased, the central sphere became very hot and started to glow forming a protostar. A wide disk formed around it’s equator.

The Formation of our Solar System Next: Due to gravity the nebula continued to collapse into a individual globular bodies and began to rotate. The Law of Conservation of Angular Momentum helps explain this phenomenon.

The Formation of our Solar System Debris within the disk began to gather into large clumps by the process of accretion (The gathering together of small bodies into larger ones by gravity). This process is responsible for the initial formation of the planets.

The Formation of our Solar System Depending on how close the planetesimals were to the sun, different materials would not be able to condense because of the heat and would be blown away by solar radiation. This would result in the planets closest to the sun to condense materials which have high boiling points like metals and rocks and planetesimals on the outer edge of the solar system would accumulate lighter materials like water, methane and ammonia

The Formation of our Solar System This would explain the rocky inner planets and gaseous outer planets of our solar system.

The Formation of our Solar System Accretion and collapse accelerated until the temperatures of the protostar reached tens of millions of degrees. The pressure and temperature reached a level to cause hydrogen atoms to fuse and make helium. This released huge amounts of energy as the protostar ignited as a thermonuclear reaction. It’s now a true star.

The Formation of our Solar System The ignition of the star blew away most of the surrounding material.

Summary of The Formation of our Solar System 1. The solar nebula began to collapse and increase its rotation 2. Centrifugal force caused the nebula to flatten and condense at the centre 3. Planetessimals formed from the accretion of dust and gas in the nebula and orbit the dense, hot central core 4. Protoplanets grew as their gravity captured more nebula material 5. The sun ignited and a solar blast blew away the remaining unconsolidated dust and gas leaving the planets in their orbit around the sun.

Homework Complete Dot Points (pg3-6)