1. Solar System
(click on picture)

3. Solar Nebula Hypothesis
• Explains that the planets formed through
condensing of the solar nebula.
• Solar Nebula: a rotating cloud of gas and
dust from which the sun and planets
formed; also any nebula from which stars
and planets may form.
• Nebula: a cloud of gas and dust in space.

4. Units for Measuring Distance in Space
1. Light Year: the distance light can travel in
one year.
• Used for distances outside our Solar System.
• Light moves at about 300,000 km/second
• So, in one year it can travel 10 trillion km.
2. Astronomical Unit (AU): the average
distance between the Earth and the Sun.
• The distance between the Earth and Sun is
equal to 1 AU.
• used for distances within our Solar System.
• 1 AU = 150 million km (93 million miles).

5. The Eight Planets
Inner/Terrestrial Planets:
• Mercury
• Venus
• Earth
• Mars
Outer/Jovian Planets:
• Jupiter
• Saturn
• Uranus
• Neptune
Between the Inner & Outer
• Asteroid Belt
Dwarf Planet:
• Pluto

6. Inner/Terrestrial Planets
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•
•
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Terrestrial: means ‘earth’ like planet.
are relatively small,
composed mostly of rock
have few or no moons.

7. Outer/Jovian Planets
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•
•
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Jovian: ‘Jupiter’ like planets
are mostly huge
mostly gaseous, ringed
have many moons

8. Temperatures on Planets
• Generally, the farther
from the Sun, the
cooler the planet.
• Differences occur
when the greenhouse
effect warms a planet
(like Venus)
surrounded by a thick
atmosphere of CO2.

9. Density of the Planets
• The outer, gaseous
planets are much less
dense than the inner,
rocky planets.
• The Earth is the
densest planet.
• Saturn is the least
dense planet; it would
float on water.

10. Mass of the Planets
• Jupiter is by far the
most massive
planet; Saturn trails
it.
• Uranus, Neptune,
Earth, Venus, Mars,
and Pluto are orders
of magnitude less
massive.

11. Gravity on the Planets
• Strongest gravitational
attraction at its surface is
Jupiter.
• Although Saturn, Uranus,
and Neptune are also
very massive planets,
their gravitational forces
are about the same as
Earth.
• Click on picture to
determine your weight on
other planets.

12. A Day on Each of the Planets
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•
•
•
A day is the length of time that
it takes a planet to rotate on
its axis (360°).
A day on Earth takes almost
24 hours.
The planet with the longest
day is Venus; a day on Venus
takes 243 Earth days. (A day
on Venus is longer than its
year; a year on Venus takes
only 224.7 Earth days).
The planet with the shortest
day is Jupiter; a day on
Jupiter only takes 9.8 Earth
hours!

13. Average Orbital Speed of Planets
• Planets travel at
different speeds.
• Each planet speeds up
when it is nearer the
Sun and travels more
slowly when it is far
from the Sun (Kepler's
Second Law of
Planetary Motion).
• Click on picture to right
and determine your age
on another planet.

14. Mercury
• Closest planet to the Sun (therefore, you can only
see it close to sunrise or sunset)
• Has a very thin atmosphere
• Heavily cratered (atmosphere too thin to break apart
incoming meteorites)
• Has no moons
• Huge range in temperatures, from -270°F to 800°F
(-168°C to 427°C).
• During the very long daytime (88 Earth-days long),
the temperatures are very high (the second-highest
in the Solar System - only Venus is hotter);
• During the long night, the thin atmosphere lets the
heat dissipate, and the temperature drops quickly.

15. Venus
• A.K.A. the ‘morning star’ or the ‘evening star’
• Hottest planet in our Solar System (due to an
atmosphere composed of CO2 which traps heat)
• Has no moons
• Venera 3 (from the U.S.S.R.) was the first
manmade object to reach Venus (launched on
November 16, 1965).
• On March 1, 1966 , the spacecraft arrived at Venus
and the capsule parachuted down to the planet, but
contact was lost just before entry into the
atmosphere.
• Earth’s sister planet.

16. Earth
• ‘3rd rock from the sun’.
• Has an atmosphere (composed of 78% nitrogen,
21% oxygen, 0.9% argon, 0.03% carbon dioxide, and
trace amounts of other gases).
• The atmosphere was formed by planetary degassing
(a process in which gases like carbon dioxide, water
vapor, sulphur dioxide and nitrogen were released
from the interior of the Earth from volcanoes and
other processes).
• Life forms on Earth have modified the composition of
the atmosphere since their evolution.
• Has one moon.
• Has water in all three states (solid, liquid, gas)

17. Mars
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•
•
•
•
4th planet from the sun.
The Red planet
About half the size of Earth
Has a dry, rocky surface and a very thin atmosphere.
North and south poles of Mars are covered by ice
caps composed of frozen carbon dioxide and water.
• Scientists have long thought that there is no liquid
water on the surface of Mars now, but recent photos
from Mars indicate that there might be some liquid
water near the surface.
• Scientists think that most of the water on Mars is
frozen in the land (as permafrost) and frozen in the
polar ice caps.

18. Mars
• Olympus Mons, the
largest volcano on Mars;
• It is perhaps the largest
volcano in the Solar
System.
• It is 17 miles (27 km) tall
and over 320 miles (520
km) across.
• It is thought to be extinct.

20. Asteroid Belt
• The area between the inner and outer planets
• The current view is that asteroids are leftover rocky matter that
never successfully formed into a planet.
• Click on the left picture and see asteroids that come close to
Earth.

21. Jupiter
• Largest planet in our solar system.
• Has a thick atmosphere, 39 known moons,
and a dark, barely-visible ring.
• Its most prominent features are bands across
its latitudes and a great red spot (which is a
storm).
• Composed mostly of gas.
• Radiates twice as much heat as it absorbs
from the Sun.

23. Jupiter’s Moons
•
Jupiter has at least 39 moons.
The Four Galilean Moons (discovered by Galileo)
1. Io (volcanically active)
2. Europa
3. Ganymede (largest moon in solar system)
4. Callisto

24. 1. Io
• is a large, rocky,
volcanically active moon of
Jupiter.
• Is the innermost of Jupiter's
four large moons and the
third largest.

25. 2. Europa
• Is a large, dense, icy
moon of Jupiter.
• Europa is the smoothest
object in our Solar
System.
• Its surface is covered
with long, crisscrossing
trackways (but few
craters) on water ice.

26. 3. Ganymede
• Is the largest moon of
Jupiter
• A large, icy, outer
moon that is scarred
with impact craters
and many parallel
faults.

27. 4. Callisto
• Is a large, icy, darkcolored, low-density
outer moon of Jupiter
that
• It is scarred with
impact craters and
ejecta.

28. Saturn
• It is the second-largest planet in our solar
system (Jupiter is the largest).
• It has beautiful rings made mostly of ice chunks
(and some rock) that range in size from the size
of a fingernail to the size of a car.
• Saturn is made mostly of hydrogen and helium
gas.
• Saturn is the only planet in our Solar System
that is less dense than water. Saturn would float
if there were a body of water large enough!

29. Saturn’s Moons
• Saturn has dozens of moons (33 discovered
as of August, 2004).
• It has 18 named moons, including:
– Titan (the largest), Rhea, Iapetus, Dione, Tethys,
Enceladus, Mimas, Hyperion, Phoebe, Janus,
Epimetheus, Pandora, Prometheus, Helene,
Telesto, Atlas, Calypso, and Pan (the smallest
named moon of Saturn). At least a dozen others
have been noted (but not named yet).

30. Saturn’s Rings

31. Uranus
• This huge, icy planet is covered with clouds and is
encircled by a belt of 11 rings and 22 known
moons.
• Uranus' blue color is caused by the methane (CH4)
in its atmosphere; this molecule absorbs red light.
• Uranus rotates on its side (along its orbital path).
• This tipped rotational axis (97.90) gives rise to
extreme seasons
• A catastrophic collision with another large body
eons ago may have tipped Uranus over on its side.

33. Uranus

34. Neptune
• This giant, frigid planet has a hazy atmosphere and
strong winds.
• This gas giant is orbited by 8 moons and narrow,
faint rings arranged in clumps.
• Neptune's blue color is caused by the methane
(CH4) in its atmosphere; this molecule absorbs red
light.
• Neptune's rotational axis is tilted 30 degrees (this is
a few degrees more than the Earth).
• This gives Neptune seasons.
• Each season lasts 40 years; the poles are in
constant darkness or sunlight for 40 years at a
time.

35. Neptune

36. A Planet vs. Pluto the Dwarf
International Astronomical
Union’s Definition of a
Planet:
• Is in orbit around the
sun.
• Is nearly round.
• Has cleared the
neighborhood around its
orbit.
International Astronomical
Union’s Definition of a
Dwarf Planet:
• Is in orbit around the
sun.
• Is nearly round
• Has not cleared the
neighborhood around its
orbit.
• Is not a satellite.

37. Pluto the Dwarf Planet
• Pluto’s Failure to Remain a Planet: It has not
cleared the neighborhood around its orbit.
• Each day on Pluto takes 6.39 Earth days.
• Each year on Pluto takes 247.7 Earth years
(that is, it takes 247.7 Earth years for Pluto to
orbit the Sun once).
• Sometimes it is even closer to the Sun than
the planet Neptune (it was that way from
January 1979 to February 11, 1999)!

38. Pluto
• Pluto has one large moon,
named Charon;
• Two minscule moons were
discovered in 2005.
• Pluto's composition is
unknown.
• It is probably made up of
about 70% rock and 30%
water. This is determined
from density calculations

39. References
• http://www.enchantedlearning.com/subject
s/astronomy/planets/
• http://www.solarviews.com/eng/jupiter.htm