1. Our Solar System
One sun
8 planets
5 dwarf planets
170 moons
Photo Credit: STSci

2. The Main Planets are…
Terrestrial Planets:
Gas Giants:
 Mercury
 Jupiter
 Venus
 Saturn
 Earth
 Uranus
 Mars
 Neptune

3. Terrestrial Planets
 These are the 4 planets closest to the sun
 They are small and have dense, hard
rocky surfaces
 These planets are similar to each other in
composition, but not in their specific
characteristics.
 Because of their different distances from
the sun- they have different surfaces.

4. Terrestrial Planets
 MERCURY: The smallest terrestrial planet,
with many craters on it’s surface and almost
no atmosphere.
 VENUS: Has a similar density and internal
structure to Earth. Venus rotates in the
opposite direction of all of the other planets.
It’s surface is almost entirely covered with
clouds and are made almost entirely of
sulfuric acid.

5. Terrestrial Planets
 EARTH: Earth is unique due water on the
surface (appx 70% of the surface is
covered!)
 MARS: Covered with rust, causing it to look
red. 95% of it’s atmosphere is CO2 and with
little cloud coverage. Mars has two polar ice
caps where some frozen H2Oand frozen
CO2 exists. Mars has a tilted axis similar to
Earth, giving it seasons.

6. The Gas Giants
 They are the 4 farthest from the sun
 They have very thick atmospheres made
mostly of hydrogen and helium
 They are much, much larger compared to
the terrestrial planets
 Because of their size, they have a much
greater mass and stronger gravity

7. The Gas Giants
 Each Gas Giant has many moons as well
as rings surrounding it.
 The Gas Giants are covered with gases
and below the clouds of gasses lies a sea
of liquid hydrogen and helium (caused by
the great pressure on the planet)
 Astronomers believe they have a dense
core hidden deep within the planet made
of rock and iron.

8. The Gas Giants
 JUPITER: Largest planet, Jupiter’s
atmosphere has a giant red spot on the
surface that is larger than Earth. This spot
is a giant storm. Jupiter has 4 beautiful
large moons (Galileo discovered) that are
visible with a telescope. (pic on p. 565)
 SATURN: Second largest, the most
spectacular and visible rings of all the gas
giants. The largest moon Titan is larger
than Mercury!

9. The Gas Giants
 URANUS: a very cold planet (compared to
the others) and is twice as far from the sun
as Saturn. Not discovered until late 1700’s.
It’s the only planet with an axis at a 90°
angle to the orbital plane. 27 total moons, 5
of the largest moons have lava flowing on
their surfaces!
 NEPTUNE: Neptune is very similar to
Uranus in terms of color and size, and is
covered in blue clouds. Discovered in mid
1800’s. At least 13 moons (may be more).

10. The bench warmers are…
Dwarf Planets:
Moons:
 Ceres
 Mercury - 0
 Pluto
 Venus - 0
 Haumea
 Earth -1
 Makemake
 Mars – 2
 Eris
 Jupiter – 63
 Saturn – 61
 Uranus – 27
 Neptune – 13
 (Pluto has 3)

11. Dwarf Planets and Pluto
 Dwarf planets are any planet who has not
completely cleared it’s path yet (the path
that it takes during it’s revolution).
 Astronomers recently discovered the other
dwarf planets in our solar system and with
the new information collected, they
reclassified Pluto.

12. Pluto
(not demoted, just found his real family!)
 Pluto is smaller than Earth’s Moon! Pluto
has three moons of it’s own. Pluto's orbit
is much more elliptical than the other
planets, at times it is closer to the sun
than Neptune.