1. The Solar System – “What kinds of objects are in the solar system?”
Chapter 21
The Solar System – “What kinds of objects are in the solar system?”
----- Meeting Notes (9/26/16 10:38) -----

2. Lesson 1 – The Structure of the Solar System
How are the inner planets different from the outer planets?
What is an astronomical unit and why is it used?
What is the shape of a planet’s orbit?

3. What is the “solar system”?
Solar system consists of:
The sun
The group of objects that orbit the sun

4. “What object do the planets in the solar system move around. ” RC-p
Objects in the solar system move around the sun.

5. Objects in the solar system – The Sun
A star – an object in space made of gases in which nuclear fusion reactions occur, producing energy
Energy is given off as light and heat
Diameter is 1.4 million km (870, 000 miles)
Diameter is 10 times larger than the largest planet, Jupiter
Made mostly of hydrogen gas
Mass makes up 99% of the mass of the ENTIRE SOLAR SYSTEM

6. Objects in the Solar System – Objects that orbit the sun
All objects that revolve around the sun are held in their orbit by the sun’s gravitational force
Planets
Dwarf planets
Asteroids
Comets

7. “What is a planet?” RC-p. 762
A planet is an object that orbits the sun and has a nearly spherical shape. The mass of a planet must be larger than the total mass of all the objects whose orbits are close by.
(This is why Pluto is no longer considered a planet. Its mass is NOT greater than the total mass of nearby orbiting objects.)

8. Inner Planets vs. Outer Planets
closest to sun
Outer planets
farthest from sun
Mercury, Venus, Earth, Mars
Made mainly of solid, rocky material
Jupiter, Saturn, Uranus, Neptune
Made mainly of ice and gases (like hydrogen & helium)
MUCH larger than inner planets (called the “gas giants”)

9. “Describe how the inner planets are different from the outer planets
“Describe how the inner planets are different from the outer planets.” KCC-p. 763
The inner planets are different from the outer planets because they are made mainly of solid, rocky material while the outer planets are made mainly of ice and gases. The outer planets are also much larger than the inner planets.

10. Dwarf Planets A spherical object that orbits the sun
It is NOT a moon of another planet
It is in a region where there are many orbiting objects nearby BUT IT DOES NOT HAVE MORE MASS THAN THOSE NEARBY ORBITING OBJECTS
Made of rock and ice
Much smaller than Earth

11. The Four Known Dwarf Planets
Ceres
Eris
Pluto
Makemake

12. “Which dwarf planet is farthest from the sun?” VC-p. 763
Eris is the dwarf planet that is farthest from the sun.
See Fig. 3, p. 763

13. Asteroids
Small, rocky objects that orbit the sun in the asteroid belt, located between Mars and Jupiter.
Usually NOT spherical
Range in size from less than a meter to several hundred kilometers (about miles)
SEE FIG. 4, Page 763

14. Comets
An object made of gas, dust and ice that orbits the sun in an oval shaped orbit

15. Assignment for tomorrow
On index cards, write the definitions for the following words: There will be a vocabulary quiz over these words on Thursday, 9/29.
• Solar system
• Star (science use)
• Planet
• Asteroids
• Comet
• Astronomical unit
• Period of revolution
• Period of rotation
• Ellipse