Formation of the Solar System

(Textbook Reference: pages 262, 264, 296, 313 – 315, 318)

Part of the Solar System / How it Formed
The Sun (pg 264, 296 & figure 8.4) / What is a nebula? Why are they called star nurseries? What is a protostar? When do stars start to emit light?
A nebula is a large cloud of dust and gas formed from the remnants of another large explosion (such as a supernova) in the universe. They are called star nurseries stars form from their dust and gases. A protostar is a star in the first stage of its formation. A protostar is formed when a nebula collapses on itself, gravity pulls the dust and gas together into small masses. As a mass grows it begins to heat up, spin, contract, heat, spin, contract, etc. A star will begin to ‘emit light’ when the temperature of the spinning protostar rises to millions of degrees Celsius – hot enough for nuclear reactions to begin.
The Rocky Inner Planets (pg 314) / Formed when spinning particles of dust and gas slammed into each other and stuck. Particles continued to stick (like a snowball), the mass became large enough that gravity causes the mass to bind together even more strongly. Masses close to the sun were pulled into it by its gravity but four large objects eventually formed the inner rocky planets.
Earth’s Moon (pg 314) / Soon after Earth was formed it may have been struck by an object about the size of Mars, causing a piece of Earth of be ‘chipped’ off. This object became the moon, ‘trapped’ around Earth by the gravitational pull of the Earth. Originally, it was debris and rubble but eventually compacted into the Moon.
Asteroid Belt (pg 315) / The text does not say how the asteroid belt specifically formed. Answer the following questions: Describe the size differences of asteroids. How old are the asteroids in the asteroid belt? Can you come up with a hypothesis as to how the asteroid belt may have formed?
Asteroids vary in size from 1000 km in diameter to the size of a grain of sand. Asteroids are about 4.56 billion years old. A hypothesis as to how asteroids formed is that they are leftover dust, gas and particles from when our Rocky Inner Planets formed.
The Gaseous Outer Planets (pg 315) / The Gaseous Outer Planets grew because ice acted as glue to cause gas and dust particles to stick together.
Minor Planets (pg 318) / The text does not say how the Minor Planets specifically formed. Can you hypothesize how these might have formed? What is the most famous Minor Planet? Altogether, what do these create? A hypothesis could be that they are gaseous planets that never got big enough when ice was acting like glue to cause gas and dust particles to stick together. The most famous Minor Planet is Pluto. Together, these crease a thin disk that forms a ring around the entire Solar System. Within this ring, there are about 25 Minor Planets.
Oort Cloud (pg 318) / What does it consist of? How does a comet fall out of orbit? What gives the comet its ‘tail’?
The Oort Cloud is the most distant region of our Solar System. It consists of billions of fragments of ice and dust and is the source of most comets. A comet falls out of its orbit by it’s a gravitational disturbance (e.g. an explosion in space). A comet’s tail is causes by ice particles breaking away from the comet because of the Sun’s heat and pushed away from the comet because of the solar wind.

Define planet: Celestial object that orbits one or more stars and is capable of forming into a spherical shape as it melds under the weight f its own gravity

Define asteroid: Rocky debris that orbits the Sun between Mars and Jupiter.

Define Oort Cloud: Most distant region of our Solar System, where (most) comets originate from.

Define comet: Celestial object made of ice and dust.

Distinguish between a planet and a star. A star creates its own light. A planet cannot create its own light but rather reflects light.

Steps in the formation of our solar system: (aka the Nebular Hypothesis)

1.  A large nebula formed from the remnants of another explosion such as a supernova.

2.  Most of the mass collected in the center forming the Sun.

3.  The rest made an accretion disc, out of which the other parts of our Solar System formed.

4.  The accretion disc started to spin.

5.  Planetismals started to combine together forming the planets.