1. he Great Galaxy in Andromeda - Credit & Copyright: John P. Gleason,
Celestial Images ASTRONOMY EDUCATION & OUTREACH
http://casswww.ucsd.edu/archive/public/astroed.html#TUTORIAL
University of California, San Diego
Center for Astrophysics & Space Sciences
http://casswww.ucsd.edu/archive/public/tutorial/scale.html
Space calendar
http://www2.jpl.nasa.gov/calendar/
http://hubblesite.org/gallery/
album/solar_system/
http://solarsystem.nasa.gov/index.cfm
http://solarsystem.nasa.gov/index.cfm

2. Chapter 5. The Solar System.
Main points:
1-Overview of solar system: 2- Origin of the solar
system.
a- Planets. a- Solar nebula theory.
b-Space debris. b- Extra-
solar planets
Sizes are to scale, but distances are not.

3. Chapter 5. The Solar System.
Main points:
If the sun were a large grapefruit (r~ 7 cm), the
Earth would be a pinhead 15 meters away.
Sizes are to scale, but distances are not.

4. Solar System Neptune
Ur
Three types of Asteroid an
u s
planets: Belt Sa
t ur
TERRESTRIAL Ju n
JOVIAN pit
Ma er
AND rs
Ea
DWARF . Ve rth
Me nu
rcu s
ry

5. Terrestrial Jovian Planets.
Planets.
Moon
Uranus
Jupiter
Neptune
Venus
Mars Saturn
Mercury Pluto
Earth
The Sun contains
about 99.8% of the mass of the Solar System

6. July 17, 2009: Forty
two years ago,
Apollo astronauts
set out on a daring
adventure to
explore the Moon.
They ended up
discovering their
own planet.

7. Some general characteristics of the planets.
Planets revolve around the sun, counterclockwise
as seen from the north pole, in the same direction
and almost in the same plane.

8. Mercury Venus Earth
Earth
Pluto Neptune
Jupiter
Saturn
Uranus
Comet

9. Mercury’s orbit is tipped 7o and Pluto’s 17.2o off
the plane of the ecliptic or plane of the solar system.

10. Inclination of planets to the plane of the ecliptic.
Terrestrial planets
Venus rotates backwards

11. Inclination of planets to the plane of the ecliptic.
Saturn
27 0 Jovian planets
Uranus rotates on its side.
•Sun’s axis is tipped 7o .

12. Of the following OBJECTS, the orbit of _______,
is the most inclined with respect to the plane of
the solar system.
a- Venus b- Earth c- Mars
d- Jupiter e- Pluto

13. The Terrestrial planets are inside
the orbit of the asteroid belt.

14. Terrestrial planets and their moons.
Counting from left to right Venus is the ______ object.
a- first b- second c- third d- fourth

15. I am the planet _____
and the large scarf of
about _____ km and
_____ km deep,
along the equator is
called ________.
My average surface
temperature is only
_______degrees.

16. I am the planet
MARS and the large
scarf of about 4 000
km and 200 km
deep, along the
equator is called
Valles Marineris.
My average surface
Olympus V al temperature is only
M on les M
arin 210 K degrees.
eris

17. Scientist believed
that more than 4
billion years ago I
had running water
on my surface.
Olympus V al
M on les M
arin If that is the case
eris
what went wrong
with me and where
is the water?

18. JOVIAN PLANETS
Jupiter, Saturn, Uranus and Neptune.

19. Comparing Terrestrial and Jovian planets
Terrestrial Jovian
Earth has the Jupiter: 11 Earth’s radius.
largest radius Saturn: 9 “
r = 6 380 km. Uranus: 4 “
Radius
Neptune: 4 “

20. Comparing Terrestrial and Jovian planets
Terrestrial Jovian
Orbital Mercury 0.39 Jupiter: 5
radius in Venus 0.7 Saturn: 10
AU Earth 1
Mars 1.5 Uranus: 19
Neptune: 30
orbital Mer. 0.24 Jupiter 11.86
period Ven. 0.65 Saturn 29.542
(years)
Earth 1 Uranus 83.75
Mars 1.88 Neptune 163.7
P2 = a3

21. Comparing Terrestrial and Jovian planets
Terrestrial Jovian
solid, rich in metals: Low % in metals and
Fe, Al, Mg, Ni and silicates.
silicates ( rocks).
Composition
Rich in gases , mostly
hydrogen and helium.
Low concentration of ices of water
low melting materials Lots of ammonia (NH ), and
3
such us ices, water methane (CH4).
and gasses
Low concentrations of metals
and silicates.
Similar in composition to the
sun. (Solar in composition)

22. Comparing Terrestrial and Jovian planets
Terrestrial Jovian
Hot molten core of
silicate and metals Core: hot molten core of silicate
(rocky core) and metals (rocky core)
Structure
Rocky mantle. Not defined
Thin crust Not defined
small atmosphere. large atmosphere.

23. Comparing Terrestrial and Jovian planets
Terrestrial Jovian
Density = High 3.9 to 5.4 Low 0.7 to 1.7 g/cm3
mass/volume g/cm3
Temperature From 273 to Cold atmospheres :
750 K less than 100 K
Surface with numerous No surface.
impact crates.
Jupiter is 316 times the mass of the Earth and Saturn’s is 96.
The rest of the planets together only have 33 Earth masses.

24. Mercury observed by Messenger,
September 5, 2011

25. Comparing Terrestrial and Jovian planets
Terrestrial Jovian
Sidereal Mercury 58.64 days Jupiter 9.9 h
Period of Venus Saturn 10.7 h
rotation 243.18 days Uranus 17.2 h
Earth 23.93 h
Mars 24.62 h
Neptune 16.1 h

26. Slow rotation
Like the sun,
the Jovian
planets have Fast
differential rotation
rotation.
Slow rotation

27. Comparing Terrestrial and Jovian planets
Atmosphere Small or absent. Large
Mercury lacks it.
Terrestrial Jovian
Ring No rings All have rings. The only
rings visible from Earth
are Saturn’s

28. Jupiter and Saturn have large internal pressure
that converts hydrogen gas to the liquid metallic
state, which is a good conductor of electricity.
No boundary between liquid and gas.
Jupiter
Saturn
Earth
Hot molten
core
Metallic
Liquid Hydrogen Atmosphere
Atmosphere

29. Comparing Terrestrial and Jovian planets
Terrestrial Jovian
Moons Few or no moons Many moons.
Mars has two small Some are larger than
and Earth one. our moon.
Mercury and Venus: Lots of smaller moons
no moons.

30. The Jovian Largest
planets have
many moons.
Some are
bigger than
our moon.

31. Moon Titan
passing in
front of
Saturn
NASA/JPLCaltech/SSI

32. Jupiter has 4 Galilean Moon: Io.
Europa, Callisto and Ganymede and
12 smaller moons.

33. Jovians
Uranus
Neptune
Jupiter Saturn

34. The Jovian planets
a- are similar in composition to the sun’s.
a- are similar in composition to the sun’s.
b- are giant planets and thus, they have large
densities.
c- rotate very slowly.
d- have cold cores, because they are far away from
the sun.
The presence or absence of atmosphere in
planets or asteroids is related to the escape
speed and surface temperature.

35. What is escape speed?
The initial speed an objects needs to
escape from the surface of a planet,
star, moon or asteroid is the……..
Vo= 5 km/s Vo= 8 km/s Vo= 11.2 km/s
mass Escape speed.
VEscape = G
radius

36. Celestial body Escape velocity
(km/s)
Moon 2.0
Mercury 4.0
Mars 5.0
Venus 10.0
Earth 11.2
Uranus 21.3
Neptune 23.5
Saturn 35.5
Jupiter 60
Sun 615
White Dwarfs 6 000 mass
Neutron Stars 210 000 VEscape = G
radius

37. If the atoms and molecules of a gas move
with an average speed similar to the escape
speed , that gas is not present in the planet’s
atmosphere.
Light molecules move faster than massive
molecules, SO light molecules like hydrogen escape
easily than the heavier ones, such as nitrogen or
carbon monoxide.

38. Moon’s escape speed: 2 km/s Mercury’s escape speed: 4 km/s
The Moon and Mercury practically do not have any
atmosphere, because their surfaces get too hot and
because they have low escape speed.

39. Recall: atoms and molecules move fast at high
temperature and slow at low temperature.
Therefore, a small planet (low escape speed) with
high surface temperature does not have an
atmosphere, but
a small planet with low surface temperature might
have an atmosphere.

40. Titan cold is cold
(100 K) and has
Mercury is hot and atmosphere
( 500 K) and
does not have
any atmosphere
Mercury and Titan have similar volumes.

41. The Jovian planets are Jupiter’s
cold and have a large escape speed:
escape speed therefore, 60 km/s ~ 5
they have large Earth’s
atmospheres.

42. The stars and most planets have Magnetic Fields.
South
Magnetic pole
re
phe
t os
gne
Ma
North Magnetic pole

43. The stars’ and planets’ magnetic field is due
to the Dynamo Effect.
Convection
Rotation + of a Magnetic
= field.
conducting
medium
M here
sp
ag
ne
to
-
The Earth, the Jovian planets, the sun and stars
have magnetic fields.

44. ct i on
ve
on .
C ne
The sun
zo rotates very
fast and has a
large
convection
zone, thus its
magnetic
field is
intense.

45. The Earth’s
magnetosphere is
the region where the
magnetic field is felt.
Magnetosphere

46. The “solar wind” consist of charged particles, protons and
electrons escaping the sun’s upper atmosphere.
Most of the particles in the solar wind are deflected by
The charged particles from the sun interacts
the Earth’s magnetosphere. A few particles spiral down
with the air molecules producing the aurorae
to the northern and southern latitudes forming the
borealis or australis.
“aurorae”

47. The charged particles in the solar wind interact
with the air molecules producing the aurorae
borealis or australis.

48. Dwarf planets.
In 2006 the International Astronomical Union
(IAU) created a new category of planets:
Dwarf planets.
Name Distance Period (Y) Location
from sun
(AU)
Ceres 4.6 4.6 Asteroid belt
Pluto 40 248 Kuiper belt
Haumea 43 285 Kuiper belt
Makemake 48 310 Kuiper belt
Eris 68 557 Kuiper belt

49. Three Dwarf Planet..
Ceres Pluto. Eris
2 247 Km 3 330 km
1000 km
In the In the Kuiper belt
Asteroid belt

50. Most of the dwarf planets are in the Kuiper belt, a
cold region, beyond the orbit of Neptune.
Pluto
Kuiper belt
Eris

51. definitions:
Icy Frozen water, gases and liquids such as:
body: NH3 ammonia, CH4 methane, CO2 .
Rocky A solid body rich in silicates,
body: SiO2 and metals: Fe, Ni, Al, and
Mg.

52. Space Debris:
Meteorites
Comets
Asteroids
Asteroids

53. Asteroids.
Asteroids are the remains of the Mars
‘planetesimals” that built the planets ~
1.5 AU
4.6 billion years ago!
Where are the asteroids ?
1- Most in the asteroid belt,
Trojan
with orbits between 1.8
AU and 3.3 AU.
2- The Trojan
asteroids, share the orbit
Tr
with Jupiter. oj an
Jupiter 5.2 AU

54. The Apollo asteroids cross the Earth’s orbit.
Many
asteroids
are in
the
Kuiper
belt,
beyond
the orbit
of
Neptune
Jupiter 5.2 AU

55. The asteroids, in the Kuiper belt, are large chunks
of solid material, mainly icy, held by gravity.

56. There are basically Three types of Asteroids:
C-type: carbonaceous, dark
S-type: silicate (rocky)
M-type: metallic; iron and nickel
Low density ~ 1.3 g/cm3 and are not
made of solid hard rock.

57. Asteroids observed by Galileo spacecraft in
the asteroid belt.

58. Most asteroids, have
irregular shapes, rotate on
their axis and come in
different sizes from large,
to small (pebbles).
The self-gravity of the
asteroids is not enough to
pull them into a spherical
shape.
About 100 000 have
been identified so far.
Ida rotating on its axis (HST).

59. Asteroid Vesta
Vesta
observed by
Dawn
spacecraft
from a
distance of
about 3,200
miles (5,200
kilometers).
on July 24,
2011. Vesta ~ 600 km is
the largest.

60. The spacecraft NEAR Shoemaker landed on the
asteroid 433 Eros on February 2001.

61. These objects are
a- rocks from the moon b- dwarf planets
c- asteroids d- meteorites

62. Some asteroids
a- have been discovered orbiting Jupiter
b- are similar in composition to Jupiter
c- have running water on their surface
d- have diameters of 2 000 miles.
e- none of the above.
e- none of the above.

63. Bayeaux Tapestry
Norman Invasion of Comet of 1577
1066

65. A Parts of a comet
near the sun
B
C
A=
B=
C=

66. Nucleus of comet Hartley 2
taken by NASA's EPOXI mission
http://solarsystem.nasa.gov/index.cfm

67. Nucleus
Irregular fluffy (lots of voids) mixture of
ices and pulverized rock (tiny particles).
Ices: water, carbon dioxide, ammonia
methane and others.
Rock: mainly pulverized silicates.
nucleus of
comet Hale, as
Diameter of nucleus: from 10 to 50 km
seen by Giotto
and a density of (0.1 to 0.25) g/cm3.
spacecraft.

68. The tails are produced Tails
by vaporizing ices and
dust (rock) from the
nucleus.
Tail
st
Du ail
T
g as
n or
Io
Comet West (1975))

69. Ion or gas tail consists of ionized gases. The
CO+ ions scatters the blue light more efficiently
than any other color and thus it looks blue
Tail
g as
n or
Io
Comet West (1975)

70. The dust tail consist of tiny dusty particles. The
dust reflects all the visible light from the sun
and looks white.
Tail
st
Du

71. Tails point away from the
sun pushed by the solar
wind and solar radiation
pressure.
Tails are ~ 150 x106 km long.

72. Coma A Neat Comet. Kitt Peak
National Observatory
Tenuous cloud of (C/2001 Q4 z)
evaporated gas, (CO2, H
, water, ammonia, etc)
and dust with a
diameter of more than 100
000 km surrounding the
nucleus.
Surrounding the coma
is an invisible layer, or
hydrogen envelope; the
hydrogen may come Coma
from water molecules.

73. The comets have
long elliptical
orbits, because
they come from far
away.
Orbit of Comet Kohoutek, 1973-
1974.
http://history.nasa.gov/SP-
4208/p391.htm

74. Oort cloud
Long period
comets (more
than 200 years of
reappearance)
Sun
come from the
Oort cloud and
short period- less The Kuiper Belt.
than 200 years -
comets come
from the Kuiper
belt.
Ort Cloud

75. Dimensions of the
U
5x10 5 A
Oort cloud.
AU
Inner radius
10 4
10 000 AU. Sun
External Planetary
radius region
50 000 AU.

76. No direct
evidence of the
Oort cloud!
Comets from the Oort cloud, come in
any direction from the sky,

77. The Kuiper belt: region of icy planetesimals.
Pluto, Charon, Triton, Quaoar, Sedna, Eris, and
more.

78. Why do comets
leave their In the Oort cloud
homes? occasional passing
stars may perturb the
orbits.
In the Kuiper belt
collision between
them, or the
gravitational force
of Jupiter.

79. A solar system object, of rocky composition
and comparable in size to a small city is most
likely.
a- a meteor
c- an asteroid b- comet
c- an asteroid d- a planet
e- a meteoroid.

80. Short period comets and origin of meteors.
First Second Third Hundredth
Orbit Orbit Orbit. Orbit
. ……
The nuclei of comets are fragile and lose lots
of matter every time they come close to the
sun leaving behind a trail of tiny particles.

81. Some definitions
Meteoroid. Small solid
particle moving towards
earth’s atmosphere.
Meteor. Trail of light.
“Shooting star’.
Meteorite. A particle that
reaches earth’s surface.
Many have been found.

82. Meteor Meteors and the meteor
Showers. showers are produced when
the Earth enters the trail of
particles left behind by comets.
The meteors
captured by Earth
increase its mass
200 tons per day.
Meteors are related to
comets!

83. Meteor showers,
seem to come
from the same
place in space.
The Leonid
meteor shower,
(November 14-
19), seems to
come from the
Leonid
constellation.

84. 1997 Leonids
from Orbit
After midnight the speed
of the meteors and the The 1833 storm
rotation of the Earth's
speed adds up improving
the chance to see a meteor

85. Meteorites.
Particles that reach earth’s surface are the Meteorites.
Meteorites endure the high temperature caused by
air’s friction .
Meteorites appear to be fragments of asteroids and
even of terrestrial planets.
Iron-Ni, with ~ 7% Ni.

86. There are basically Three types of meteorites:
C-type: carbonaceous, dark
S-type: silicate (rocky)
M-type: metallic; iron and nickel
So: three types of asteroids. Fe

87. Meteorite from the
surface of Mars. It was
hurled into space by
and impact.

88. Which of the following is most likely related
to comets?
a- asteroids
b- meteorites
c- meteors
c- meteors
d- dwarf planets
e- a & d.

89. Age of Solar System .
- All objects in the
solar system were
formed around the
same time.
- The age of the
meteorites gives the
age of the solar
system. Radioactive
dating,
Go to. http://lectureonline.cl.msu.edu/~mmp/applist/decay/decay.htm

90. Radioactive sample
In ten hours
at t = 0 hours
Half life time - 10 hours. daughter
The age of rocks is found comparing the original
amount of radioactive (unstable) atoms and daughter
abundance.

91. Examples of half life.
Parent Daughter Half life
years
238
U 206
Pb 4.5 billion
40
K 40
Ca, 40Ar 1.3 billion
226
Rb 87
Sr 47 billion
Half-life is the time in which half of the
radioactive mass decays.

92. The meteorites and the rocks from the moon are
about 4.6 billion years old. This is the age of the
solar system.
Most of the oldest rocks found on Earth are only
about 3.9 to 4.1 years old.
The oldest rocks have been
destroyed because the Earth is
very active.

94. Decay of In 3 billion
“Nonex” years how
many
particles of
Nonex have
decayed?
a. 150
b. 1050
c. 220
c. 1050
d. 1000
1200 - 150 = 1050

95. Summary:
Meteors: come from comets they are fragile and
easily burnt upon entering the atmosphere.
Meteorites: come from asteroids or planets. They are
hard and make it to Earth.
Comets have highly elliptical orbits.
Asteroids are solid with rocky composition (carbon,
silicates and metals).
Objects in the Kuiper belt are icy and very cold.
The age of the solar system, about 4.9 billion years,
is estimated from the age of the meteorites.

96. See this video
http://www.youtube.com/watch?
v=Uhy1fucSRQI