The document summarizes the key characteristics of the terrestrial and gas giant planets in our solar system. It describes the four inner, rocky terrestrial planets closest to the sun - Mercury, Venus, Earth, and Mars. It then discusses the outer gas giants - Jupiter, Saturn, Uranus, and Neptune - which are larger and composed primarily of hydrogen and helium. It provides details on attributes such as composition, atmospheres, temperatures, moons, and orbital periods. Pluto is briefly mentioned at the end as a former planet now classified as a dwarf planet.

1. Our Solar System
Ag Earth Science
Mr. Silva

2. The Terrestrial Planets
 The four planets closest to the sun.
 Mercury, Venus, Earth, and Mars
 The terrestrial planets are much like
Earth.
 The four inner planets:
 Are relatively small and dense
 Have rocky surfaces (crusts), mantels, and
iron cores

3. More on the First Four
 Mercury and Mars have crusts that are
scarred by craters.
 Earth and Venus do not have craters because
their surface is continually eroded.
 Common characteristics of the terrestrial
planets:
 Higher temperature than outer planets
 Have few (if any) moons
 No rings around the terrestrial planets

4. Mercury
 Characteristics:
 Smallest and closest to the sun
 Dense with large Iron core
 Fastest moving planet - 88 day revolution
 Temperature and Atmosphere:
 It takes 88 days for sunrise to sunset
 During the day, temperature = 430 deg. C
 At night, temperature = 170 deg. C
 Virtually NO atmosphere - temp makes particles
move fast, little gravity makes it easy for
particle to escape into space

5. Venus
 Characteristics:
 The brightest object in Earth’s night sky (with the
exception of the moon)
 Rotates in the opposite direction to which it revolves
around the sun
 Rotation rate is VERY slow - takes 243 days to rotate on
its axis (a day is longer than a year!)
 Temperature and Atmosphere:
 Difficult to study because of clouds
 Atmosphere is so thick that pressure is 90x greater than
that on Earth
 Atmosphere is made mainly of CO2 which traps heat and
increases surface temp
 Surface temp is 470 deg. C

6. Earth
 Earth = Suitable atmosphere and
temperature for water to exist as liquid!
 H2O supports tens of thousands of different
species of living organisms and has shaped
the surface through erosion.
 Has gravity to hold most gas molecules =
thick atmosphere
 Geologically alive!

7. Mars
 Characteristics:
 Most Earth-like of all planets
 Weathering of iron-rich rock give it red tint
 Has largest volcano in solar system (Olympus Mos)
 Atmosphere and Temperature:
 Thin atmosphere and distance = temp range of -140
deg. C to 20 deg. C
 Atmosphere is mainly CO2 (much like Venus but
much thinner)
 No liquid water on Mars - but thought that there
once was
 Mars also has seasons due to the tilt of its axis

8. Asteroids
 Beyond Mars is a region known as the
asteroid belt
 Astronomers have discovered more than
10,000 asteroids and more are thought to
exist
 Asteroid are:
 >1 kilometer in diameter
 Only 3 are larger than 500 kilometers across
 It used to be thought that asteroids were
fragments of a shattered planet - not what is
thought today

9. Scientific Discovery
• It is said that Scientific Discovery can happen in
different ways:
• Discovery by accident
• Theories predict phenomena that scientists try to find
• Uranus (Yoor uh nus) and Neptune were discovered by
these two methods
• Uranus discovered by chance - thought it was a dim
star
• Neptune was found when someone predicted that
there was something affecting Uranus’ orbit.

10. Gas Giants
• The “Gas Giants” are the next four planets in the
Solar System
• Jupiter, Saturn, Uranus, and Neptune
• Common Characteristics:
• Much colder than terrestrial planets
• More massive than terrestrial planets
• Composed of mainly Hydrogen and Helium
• No solid surface - intense pressure means that H and He
exist in liquid form
• Small dense cores of metal and rock

11. Jupiter
• The first planet beyond the asteroid belt and the
largest/massive planet in the solar system
• Jupiter could hold more than 1,300 Earths and is named for
the ruler of the Roman Gods
• Jupiter is composed of mainly H and He
• Atmosphere:
• Clouds on Jupiter move fast because Jupiter moves fast
• Brown bands are colder and move faster than the white bands
• The great red spot is a giant storm on Jupiter, caught between bands
of warm and cold air
• These storms don’t dissipate like they do on Earth - the Great Red
Spot was first observed in 1664

12. Jupiter’s Moons/Fun Facts
• Jupiter has over 50 moons!
• Ganymede and Callisto are the size of Mercury
• Io and Europa are the size of Earth’s moon
• Ganymede, Io, and Europa have metal cores and rocky
mantels (Io is covered in active volcanoes - Ganymede, Europa,
and Callisto are covered in ice)
• Scientists believe that the ice on Europa rests on top of a liquid
salt water ocean
• FUN FACTS:
• One day on Jupiter is less than 10 hours on Earth
• It takes almost 12 Earth years for Jupiter to revolve around the sun
• The Great Red Spot is the size of three Earths

13. Saturn
• The second largest planet in the solar system and known for its
rings!
• Rings are ice particles or ice covered rock - most are snowball sized
• Rings are 274,000 kilometers in diameter yet only tens of meters thick
• Atmosphere:
• Largest atmosphere of any in the solar system
• Saturn has the lowest average density of any planet
• Atmosphere is made of H and He
• Scientists think that He condenses and as He raindrops fall towards the
center of the planet, their energy is changed to heat

14. Uranus
• Uranus is another Gas Giant which is extremely cold and has
an atmosphere made of H and He
• Like other Gas Giants, it is assumed that Uranus has a rocky
core surrounded by a thick mantel layer of liquid water and
dissolved ammonia
• Uranus has rings, although they are not as impressive or
reflective as Saturn’s rings
• Uranus is tiled on its side, and it rotates in the complete
opposite direction that it revolves around the sun
• The northern and southern hemispheres alternate between
being exposed to the sun for years - causing disturbances on the
surface

15. Uranus’ Moons/Fun Facts
• Uranus has more than 20 moons
• FUN FACTS:
• Uranus is thought to have been tilted on its side by a
collision with another planet sized object
• The rings and moons of Uranus follow the irregular
rotation of the planet
• One day on Uranus is about 17 Earth hours
• It takes almost 84 Earth years for Uranus to revolve
around the sun
• Blue-Green color comes from methane in the atmosphere

16. Neptune
• Neptune has approximately the same size and
composition of Uranus
• Neptune has clearly visible cloud patterns in its
atmosphere, and gets the blue tint from methane in
the atmosphere
• Neptune has large storms in its atmospere which last
for many years
• The Great Dark Spot was identified by Voyager 2 in 1989
and then disappeared in 1994

17. Neptune’s Moons/Fun Facts
• Neptune has 8 moons
• Triton is the largest moon - has a thin
atmosphere and an icy crust
• FUN FACTS:
• Neptune also has a small band of coal colored
rings
• One day on Neptune is about 15 Earth hours
• It takes almost 165 Earth years for Neptune to
revolve around the sun.

18. Pluto – A Planet No More 
• Pluto is small and dense - much like the moons
of the Gas Giants
• Pluto is made up of a mixture of ice and rock
• Pluto has a single moon - Charon - which is
almost identical in size (almost like a double
planet)
• Pluto is now considered a “dwarf planet” and
is not recognized as having official planet
standing