The Sun is a middle-aged, average sized yellow star that is made up mostly of hydrogen and helium. It is about 4.6 billion years old and located 93 million miles from Earth. The Sun generates heat and light through nuclear fusion reactions in its core that convert hydrogen into helium. It is the center of our Solar System and contains over 99% of the mass in the entire system. The Solar System also includes eight official planets that orbit the Sun, along with dwarf planets, moons, asteroids, comets, and other small bodies.

4. 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

5. 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

6. 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.

7. Solar flaresSolar flares
Powerful erruptions of
particles that shoot into
space
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.
The erupting particles
strengthen the solar wind,
which is made of fast-
moving gases that travel
through space.

8. Solar WindSolar Wind
Fast moving gases that can travel in spaceFast moving gases that can travel in space

9. Solar Winds cause AurorasSolar Winds cause Auroras
The solar wind can
disrupt radio waves and
cause auroras.
The solar wind can
disrupt radio waves and
cause auroras.
Aurora seen
from space

10. Solar ProminenceSolar Prominence
A huge arc of gass
that extends into
space
A huge arc of gass
that extends into
space

11. Energy from the SunEnergy from the Sun
4 hydrogen nuclei fuse to form 1 helium nucleus4 hydrogen nuclei fuse to form 1 helium nucleus
Huge energy
release

12. Nuclear Fusion
In 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.

13. Energy from the SunEnergy from the Sun
Uneven heating
affects weather
Uneven heating
affects weather
Powers the
water cycle

14. Energy from the SunEnergy from the Sun
Uneven heating
causes winds
Uneven heating
causes winds
Provides energy
for living things
producers

15. Life Cycle of StarsLife Cycle of Stars
A star forms
from rotating
clouds and dust
called a
nebula
11

16. Life Cycle of StarsLife Cycle of Stars
Gravity and
other forces
cause the nebula
to collapse.
Clouds begin to
glow as the
temperature
rises forming a
Protostar
22

17. 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 -

18. Life Cycle of StarsLife Cycle of Stars
When gas
pressure inside
the star equals
gravity, the star
becomes stable
and forms a
Main-
sequence
Star
33
Nuclear fusion begins when
the temperature reaches 10 million C

19. Life Cycle of StarsLife Cycle of Stars
The outer part
of the star
expands over
time, while the
core contracts
forming a
Red Giant
44
Red giants are very bright,
but cooler star.
Very large red giant stars
are known as Super Giants.
Very large red giant stars
are known as Super Giants.

20. Life Cycle of StarsLife Cycle of Stars
The outer
layers of the
star are
released
forming a
Planetary
Nebula
55

21. Life Cycle of StarsLife Cycle of Stars
66
Over time the
star shrinks
forming a
White
Dwarf

22. Life Cycle of StarsLife Cycle of Stars
Out of nuclear
fuel, the star
eventually
fades into a
Black
Dwarf
77

23. Life Cycle of StarsLife Cycle of Stars

24. Alternate Life Cycle of Huge StarsAlternate Life Cycle of Huge Stars
44
Very large red giants stars are known as Super GiantsVery large red giants stars are known as Super Giants

25. Alternate Life Cycle of Huge StarsAlternate Life Cycle of Huge Stars
5
And
6
5
And
6
A Supernova is an explosion of a star accompanied by
emission of radiation and light.
A Supernova is an explosion of a star accompanied by
emission of radiation and light.

26. Alternate Life Cycle of Huge StarsAlternate Life Cycle of Huge Stars
77
Both cycles end with a Black DwarfBoth cycles end with a Black Dwarf

27. 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

28. Chapter 7 Lesson 2 pages 246-251

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

30. Your Parents’ Solar System

31. The Sun and the bodies that
revolve around it make up the
solar system.
Solar System Song

32. 21st
Century Solar System

33. Sun
Terrestrial
Planets
Asteroid Belt
Jovian
Planets
Kuiper Belt
Oort Cloud
The 21st
Century Solar System

34. The Solar System:
List of Ingredients
Ingredient
Sun
Jupiter
Other planets
Everything else
Percent of total
mass
99.8%
0.1%
0.05%
0.05%

35. The Sun dominates the Solar
System

36. 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

37. The Terrestrial Planets
Earth
(1 M⊕)
Mars
(0.11 M⊕)
Venus
(0.82 M⊕)
Mercury
(0.055 M⊕)

38. 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

39. The Jovian Planets
Jupiter
(318 M⊕)
Uranus
(15 M⊕)
Saturn
(95 M⊕)
Neptune
(17 M⊕)

41. 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)

42. Dwarf Planets

43. 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.

44. 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.

45. The Giant Moons

46. Pluto
Triton
Titan
Callisto
Ganymede
Moon
Io
Europa
Mercury
Rhea
Iapetus
Titania
Oberon
Pallas
Vesta
Hygeia
Mimas
Enceladus
Miranda
Proteus
Ceres
Tethys Dione
Ariel Umbriel
Charon

47. 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

48. Kuiper Belt

49. 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.

50. Oort Cloud

51. 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.

52. Asteroids
253 Mathilde 951 Gaspra 243 Ida

53. Meteor burning up in the
atmosphere.

54. Comet P/Halley Comet P/Wilt

56. Is Pluto a Planet?
What to consider?
• Size?
• Shape?
• Orbit?
• What is it made
of?

57. IAU Definition of a Planet
In 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

58. IAU Definition of a Dwarf Planet
In 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