1. Planets Surfaces of planets have a….
Terrestrial or Rocky Surface (Inner Planets)
2. Gaseous Surface (Outer Planets)
Mercury, Venus, Earth, and Mars
Jupiter, Saturn, Uranus, Neptune

2. Gaseous Planets are considerably
LARGER!
Question 1: Which celestial object has a similar composition to Saturn?
SATURN’S Diameter=
120,200 kilometers
Made of Helium and Hydrogen.
( Has a small, rocky core)
EARTH’S Diameter=
12,756 kilometers
Saturn has a diameter
9.4 times
larger than Earth’s.

3. Planets may have… RINGS!!
Tidal Forces, breaking up debris, form them. Sometimes even their own satellites.
Size of particles: 1mm-10 m in diameter.
Made of rock and/or ice.
Such as: Jupiter, Saturn, Uranus, and Neptune.

4. Movement of Planets is based on revolution around the …
Question 3: What is this?
SUN
All on the same plane.
Pluto is 17° off the plane.

5. And….rotation on the planet’s
AXIS
Also, while Earth has a tilt of 23.5º, Venus is tilted by 177º and Uranus is tilted by 98º!
Mercury has no tilt!

6. Moons ORBIT Moons are studied in relation to the planet they…
Question 4: Besides the moon, what else orbits the Earth?
Moons are studied in relation to the planet they…
Not all planets have moons, such as…
ORBIT
MERCURY AND VENUS

7. Asteroids: They were found in between Mars and Jupiter.
Astronomers thought at one time…
There were 13 planets.
The 9 we are aware of (includes Pluto) and Ceres, Vesta, Juno, and Pallas.
They were found in between Mars and Jupiter.
One by one, they found many more objects like the 4 “new planets”.
So, they changed them from “planets” to “dwarf planets” and identified their location as the asteroid belt.

8. Asteroids cont.
What do asteroids revolve?
ASTEROID BELT :Located between the inner planets and the outer planets.
Def: Rocks greater than 100 m in diameter.

9. COMETS
Question 5: Why does the tail emerge?
The main body or head is composed ice and rock particles mixed with gas, methane and ammonia.
(Similar to dirty snowballs)
And a TAIL that emerges as the comet gets CLOSER to the sun during its orbit
Tail Head

10. The tail always points _________ from the Sun.
AWAY
Question 6: Why would this be true?
Comets have a unique long, narrow ________________ orbit.
ELLIPTICAL
Located at the very edge of the Solar System. Past Neptune’s orbit.

11. METEOROIDS Chunks of rock that move about the Solar System.
Less than 100 m in diameter.
Smaller than asteroids.
Could be part of
old comets so
they are also…
smaller than comets.

12. Can be called…
A meteor : A meteoroid that burns up in the Earth’s atmosphere. OR
A meteorite: A meteoroid that strikes a planet or moon.

13. Pluto debate:
Pluto is located in the “Kuiper Belt” (Outside Neptune’s orbit).
It is similar to the asteroid belt, but all material is made of ice/rocks (too far from the Sun).
Astronomers found many “objects” in the same location, recently.
Made them think back to Ceres, Vesta, Pallas, and Juno.
So, the International Astronomical Union (IAU) met in 2006 to settle the matter.
Decided Pluto would be considered a “Dwarf Planet”.
The “dwarf planets” are round like planets, but do not clear out their orbits of debris.

14. Take a moment to answer the “Follow-Up Questions” on your own
Take a moment to answer the “Follow-Up Questions” on your own. Try not to use your notes…

15. Add the following terms to your “SUPER CONCEPT MAP” list on the bottom of p. 23:
Ceres
Asteroids
IAU 8
Pluto
Comets
Kuiper Belt
Rings
Orbit
Rock
Meteors
Moons
Meteoroids
Sun
Asteroid Belt 9