Our Sun– A middle-aged, average

sized, Yellow star

– Made of mostly Hydrogen & Helium

– 99.8% of the mass in our Solar System

– 4.6 billion years old

– 93 million miles from the Earth

Our Sun• A giant sphere of hot glowing

gas, called plasma

• Shines because it is hot:– Surface Temp ~5500 C– Mostly Visible, UV & IR light

• Kept hot by nuclear fusion in its core:

– Builds Helium from Hydrogen fusion.

– Will shine for ~12 billion years

Sunspots• Dark areas on the Sun’s surface.• cooler than the surrounding area• The number of sunspots and location are

changing in a regular, 11 year cycle.

Solar flares

Powerful erruptions of particles that shoot into

space

The erupting particles strengthen the solar wind,

which is made of fast-moving gases that travel

through space.

Solar Wind

Fast moving gases that can travel in space

Solar Winds cause Auroras

The solar wind can disrupt radio waves and

cause auroras.

Aurora seen from space

Solar Prominence

A huge arc of gass that extends into

space

Energy from the Sun

4 hydrogen nuclei fuse to form 1 helium nucleus

Huge energy release

Nuclear FusionIn the early 1900’s, Albert Einstein discovered that matter and energy are interchangeable. Matter can be converted to energy as demonstrated by E = mc2 Where E is energy, m is mass and c is the speed of light.

Energy from the Sun

Uneven heating affects weather

Powers the water cycle

Energy from the Sun

Uneven heating causes winds

Provides energy for living things

producers

Life Cycle of Stars

A star forms from rotating

clouds and dust called a

nebula

1

Life Cycle of Stars

Gravity and other forces

cause the nebula to collapse.

Clouds begin to glow as the temperature

rises forming aProtostar

2

HL Tauri — a star system that is just being born.

The proto-planetary disk surrounding a young star 450 light-years away. The concentric rings cutting through the glowing gas and dust are tracks etched out by planets being spawned inside the disk.

baby planets forming around a star - Discovery News 

Life Cycle of Stars

When gas pressure inside the star equals gravity, the star becomes stable and forms a

Main-sequence

Star

3

Nuclear fusion begins when the temperature reaches 10 million C

Life Cycle of Stars

The outer part of the star expands over time, while the core contracts forming a

Red Giant

4

Red giants are very bright, but cooler star.

Very large red giant stars are known as Super Giants.

Life Cycle of Stars

The outer layers of the star are released forming a

PlanetaryNebula

5

Life Cycle of Stars6

Over time the star shrinks forming a

WhiteDwarf

Life Cycle of Stars

Out of nuclear fuel, the star eventually fades into a

BlackDwarf

7

Life Cycle of Stars

Alternate Life Cycle of Huge Stars4

Very large red giants stars are known as Super Giants

Alternate Life Cycle of Huge Stars

5And

6

A Supernova is an explosion of a star accompanied by emission of radiation and light.

Alternate Life Cycle of Huge Stars7

Both cycles end with a Black Dwarf

Astronomy – the study of planets, our moon, stars (including our sun) and the universe.

Constellation – a group of stars that forms a pattern

Star chart – a map of the night sky

Chapter 7 Lesson 2 pages 246-251

The solar system is a small part of a much larger system called the Milky Way.

Your Parents’ Solar System

The Sun and the bodies that revolve around it make up the solar system.

Solar System Song

21st Century Solar System

Sun

Terrestrial Planets

Asteroid Belt

Jovian Planets

Kuiper Belt

Oort Cloud

The 21st Century Solar System

The Solar System: List of Ingredients

Ingredient

SunJupiterOther planetsEverything else

Percent of total mass

99.8% 0.1%

0.05% 0.05%

The Sun dominates the Solar System

Terrestrial Planets• Mercury, Venus, Earth & Mars

– “Earth-Like” Rocky Planets– Largest is Earth– Only in the inner solar system

• Rocky Planets:– Solid Surfaces– Mostly Silicates and Iron – High Density: (rock & metal)– Earth, Venus, & Mars have atmospheres

The Terrestrial Planets

Earth(1 M)

Mars(0.11 M)

Venus(0.82 M)

Mercury(0.055 M)

The Jovian Planets• Jupiter, Saturn, Uranus & Neptune

– Largest Planets: at least 15 times mass of Earth.– Only in the outer solar system (5 to 30 AU)– No solid surfaces (mostly atmosphere)– Low density

• Gas Giants: (Jupiter & Saturn)– Thick H/He atmosphere, liquid hydrogen mantle, ice core

• Ice Giants: (Uranus & Neptune)– Ice/rock core & mantle, thin H/He atmosphere

The Jovian Planets

Jupiter(318 M)

Uranus(15 M)

Saturn(95 M)

Neptune(17 M)

Dwarf Planets

• Defined by the IAU in 2006• Dwarf Planets:

– Ceres: first of the Asteroids, discovered in 1801– Pluto: trans-Neptunian object discovered in

1930– Eris: trans-Neptunian object discovered in 2005– Haumea (trans-Neptunian, suspected)– Makemake (trans-Neptunian, suspected)

Dwarf Planets

The Giant Moons

• Moon: any natural satellite orbiting a planet or dwarf planet

• Giant Moons:– Earth: The Moon (Luna)– Jupiter: Io, Europa, Ganymede, & Callisto – Saturn: Titan – has an atmosphere– Neptune: Triton – has an atmosphere

• Many smaller moons, both rocky & icy.• Only Mercury & Venus have no moons.

The Giant Moons

• Moon: any natural satellite orbiting a planet or dwarf planet

• Giant Moons:– Earth: The Moon (Luna)– Jupiter: Io, Europa, Ganymede, & Callisto – Saturn: Titan – has an atmosphere– Neptune: Triton – has an atmosphere

• Many smaller moons, both rocky & icy.• Only Mercury & Venus have no moons.

The Giant Moons

Pluto

TritonTitan

Callisto

Ganymede

Moon

Io

Europa

Mercury

Rhea

Iapetus

Titania

Oberon

Pallas

Vesta

Hygeia

Mimas

Enceladus

MirandaProteus

Ceres

Tethys Dione

Ariel Umbriel

Charon

Kuiper Belt

• Class of icy bodies orbiting beyond Neptune.– Found only in the outer Solar System (>30AU)– Astronomical Units, AU.  One AU is the average

distance between the Earth and the Sun, 93 million miles, or 150 million kilometres. 

• Examples:– Pluto & Eris (icy dwarf planets)– Kuiper Belt Objects (30-50AU)– Charon, Pluto’s large moon– Sedna & Quaor: distant large icy bodies

Kuiper Belt

Oort Cloud

• Spherical cloud of comets.– Extends out to almost 50,000 AU (1 light-year)– May contain trillions of comets– The outer edge is the farthest reach of the Sun’s

gravitational pull.– There are no confirmed observations – its

existence is theoretical only.

Oort Cloud

The Leftovers (small bodies)• Asteroids:

– Made of rock & metal (density 2-3 g/cc)– Sizes: Few 100km to large boulders– Most are found in the Main Belt (2.1-3.2 AU)

• Meteoroids:– Bits of rock and metal– Sizes: grains of sand to boulders

• Comets:– Composite rock & ice “dirty snowballs”– Longs tails of gas & dust are swept off them when

they pass near the Sun.

Asteroids

253 Mathilde 951 Gaspra 243 Ida

Meteor burning up in the atmosphere.

Comet P/Halley Comet P/Wilt

Is Pluto a Planet?

What to consider?• Size?• Shape?• Orbit?• What is it made

of?

IAU Definition of a PlanetIn 2006, the International Astronomical Union

(IAU) came up with the following definition of a planet: orbits the Sun has sufficient mass for its self-gravity to overcome

rigid body forces so that it assumes a hydrostatic equilibrium shape (i.e., it is spherical),

has cleared the neighborhood around its orbit, is not a satellite

IAU Definition of a Dwarf PlanetIn 2006, the International Astronomical Union

(IAU) came up with the following definition of a dwarf planet: orbits the Sun has sufficient mass for its self-gravity to overcome

rigid body forces so that it assumes a hydrostatic equilibrium shape (i.e., it is spherical),

has not cleared the neighborhood around its orbit, is not a satellite