Our Solar Centre

The Sun An Example of a Solar Tornado

Has solar tornadoes A tall funnel of

twisting plasma mmm! Can be 20,000km

(diameter) and spins at 500,000km/h

Has a temperature of several million degrees Celsius

The Sun – a Typical Star

Composed mainly of: Hydrogen Helium

Also has heavier elements: Iron Carbon Oxygen

Was born about 5 billion years ago, and will live for about 5 billion more years

The Nature of the Sun Emits radiation in almost all forms found

in the electromagnetic spectrum Visible light, UV radiation (causes sunburn)

Its mass is estimated by observing how fast the planets, etc. orbit around it

Nuclear reactions in the Sun are the same ones in the most powerful hydrogen bomb Hydrogen is converted into Helium (releases

ENERGY)

Layers of the Sun 6 main layers:

1. Core Inner part, temps at 15 million degrees Celsius Where nuclear fusion happens

2. Radiative Zone Outside the core, dense plasma Light takes 100,000 years to pass through it (meaning...?)

3. Convective Zone Big bubbles of hot plasma ooze up to surface, w/energy Cool plasma come down from surface to heat up again Constant circulation of plasma is called convection

4. Photosphere Boundary between inside and outside of Sun, making it yellow What we see on Earth has the lowest temperature of 5500

degrees C

5. Chromosphere Reddish, but can’t see it unless there’s a solar eclipse b/c of

photosphere

6. Corona Outermost layer, extends for millions of km; most visible during

solar eclipse

Label Our Sun!!

Surface Features of the Sun The Sun has a

magnetic field Generated by

movement of plasma deep in Sun

It extends far out into space

Very powerful

Surface Features of the Sun

Sunspots A region on surface of

the Sun that’s cooler than surrounding areas

Where magnetic field is extremely strong

This slows down convection no mixing of plasma Cools from 600oºC

4000ºC

Every 11 yrs, max # sunspots reached

Prominences A large, usually

curved, bright stream of particles

Extends out from photosphere into corona

May last for many hours

Solar Flares Massive explosion

at surface of Sun Interacts with

chromosphere and corona

Flings hot plasma into space

Coronal Mass Ejection Extremely powerful kind

of flare Large amount of plasma

is thrown out at 1000km/s

Earth’s magnetic field protects us when this meets the Earth

Causes auroras Can damage orbiting

satellites and electrical transmission lines

Learning Checkpoint

1. Which two elements make up more than 99% of the Sun?

2. Where in the Sun does nuclear fusion occur?

3. Name four types of surface features of the Sun.

4. How can a coronal mass ejection on the Sun cause damage on Earth?

Sun’s Effects on Earth

1. Solar Wind Constant flow of

charged particles streaming out of the Sun’s surface in all directions

Helped to create the solar system

Electrical equipment can be damaged by this

2. Aurora Borealis (Northern Lights)

Solar wind creates this display of green, yellow, and red light in the skies

Aurora Australis (Southern Lights)

Happens when charged particles of solar wind collide with atoms in Earth’s atmosphere

Particles are trapped from solar wind in magnetic field and taken towards north and south poles

How the Solar System Formed After Sun was formed (from what!?!?) the leftover

dust, gases, etc. in nebula continued to spin This created a disk around the new star

Bodies began to form Created our planets, moons, asteroids, comets

This is how other star-and-planets systems formed too

Planet: a celestial object orbiting one or more stars; can form a spherical shape DOES NOT create and radiate own light just

reflects light of star(s) it orbits

How the Solar System Formed

Rocky Inner Planets

Formed when spinning dust and gas slammed into each other and started sticking together

Larger particles made more collisions and grew faster

Gravity caused them to contract and bind together

Objects too near the Sun got sucked into it Four large objects lasted: Mercury,

Venus, Earth, Mars

Earth’s Moon

Few hundred million years later...something as big as Mars may have hit the Earth

Objects re-melted and mixed Metal core melded with Earth’s core Crusts melded together

Earth cooled Pieces of debris from collision were

caught by Earth’s gravity and eventually compacted into the Moon

Mars is the only other rocky planet with moons!!

Asteroid Belt

Between Mars and Jupiter Small as grains of sand – 1000km across Scientists look for these near other stars

Could indicate there are rocky planets there too!! This is where we got the age of the solar

system Asteroids fell to Earth and oldest one was 4.56

billion Earth was therefore formed at the same time Sun must have been around while earlier

Gaseous Outer Planets

Jupiter, Saturn, Uranus, Neptune After asteroid belt, “snow line”

On Sun side of this line, it’s where Sun’s radiation keeps H2O in gas phase

In snow line, water’s cooled and forms droplets, then freezes

Ice acted as a glue for gas and dust to stick together these planets grew faster!!

All gas giants are orbited by many moons Jupiter and Saturn each have more than 60!!

Minor Planets After gas giants, many large balls of ice

formed minor or dwarf planets Pluto: most famous

3 moons: Nix and Hydra (tiny), and Charon (1/2 Pluto)

Millions of objects besides these orbiting the Sun Some larger, some smaller, than Pluto Create a thin disk like asteroid belt around

entire solar system 25 of them are large enough to be considered

minor planets

Comets and Meteors Oort Cloud: most distant region of SS,

consisting of billions of fragments of ice and dust major source of comets

Comet: celestial object made of ice and dust Tail is created by sun heating and breaking apart

some of the ice particles Meteoroid: small pieces of rock/metal

travelling throughout the solar system (no path) Meteor: meteoroid that enters Earth’s atmosphere

and begins to burn up because of FRICTION Meteorite: a meteor that does not burn up completely

and hits Earth

Earth in Motion

At equator: 12 h daylight, 12 h night

In Arctic: some days, Sun doesn’t set (summer) and some days, Sun doesn’t rise (winter)

What causes this? Tilt of the Earth on its axis

Two Types of Motion

Rotation Revolution

One complete spin (counter clockwise) of the Earth on its AXIS

Takes about 24h Earth moves at 1670

km/h Axis is tilted at 23.5º Creates day and

night

One complete orbit of Earth around the SUN

Takes about 1 year

Creates seasons Tilted axis + revolution Tilted TO Sun = summer Tilted AWAY FROM Sun =

fall

Rotation and Revolution

The Moon

1/6 Earth’s mass Also rotates on an axis Rotation and revolution are about equal

27.3 days, moon rotates and revolves once This is why we always see the same side of the

moon Reflects Sun’s light changes in look

(phases) One complete change of phases lunar cycle Full moon: Earth between moon and sun New moon: moon between Earth and sun

Eclipses

Solar Eclipse

Lunar Eclipse

When moon blocks Sun’s light to Earth

Two types1. Partial: Sun is partially

blocked2. Total: Sun is completely

blocked

When Earth blocks Sun’s light from shining on moon

Two types1. Partial: moon is partially

blocked2. Total: moon is completely

blocked

Tides The alternate rising and falling of level

of oceans everyday Caused by:

Rotation of the Earth in the presence of the Moon

Rotation of the Earth in the presence of the Sun

Example: Bay of Fundy Largest difference between high tide and tow

tide levels (as much as 17 m in one day!)