1. Overview of the Solar System Shaped like a thin disk
Chapter 7 Astronomy
Overview of the Solar System
Shaped like a thin disk
Held in place by the Sun’s gravitational force

2. Planets, to correct relative size

3. 1 AU Astronomical Unit Average distance from Earth to Sun 149,597,870
1 AU Astronomical Unit Average distance from Earth to Sun 149,597, kilometers

4. Artist’s view of the Solar System
Figure 7.1

5. Planets and their orbits
Figure 7.2

6. Sun
Over 700 times more massive than rest of bodies in solar system
Mostly hydrogen and helium (from spectroscopy)
Fusion of hydrogen into helium creates heat & light

7. The Planets and Sun to scale
Figure 7.3

8. Measuring a planet Figure 7.5
Observe motion of a satellite orbiting planet. Determine satellite’s distance (a) from planet and orbital period, P. Use Newton’s form of Kepler’s third law.
Insert measured values of a and P, and value for constant G. Solve for M.
Average density () is mass (M) divided by volume (V )
Measure angular size of planet and use relation
between angular size and distance to solve for R.
For a spherical planet of radius R

9. Mercury, Venus, Earth, Mars Smaller Thin or no atmosphere
Inner Planets
Mercury, Venus, Earth, Mars
Smaller
Thin or no atmosphere
Made of rock w/ iron rich cores

10. Jupiter, Neptune, Saturn and Uranus Same core 70% hydrogen
Outer planets
Jupiter, Neptune, Saturn and Uranus
Same core
70% hydrogen
No solid surface, massive atmospheres, covered in oceans

11. Sketches of the interiors of the planets
Figure 7.6

12. Photo of an interstellar cloud
Figure 7.7

13. Origin(4.5 Billion years ago)
Disk shaped cloud of gas & dust rotates & is collapsed by gravity
Heat generated in center and fusion occurred (Sun)
Dust particles stick together to form planets(accretion)

14. 4. Outer planets become bigger due to lower temperature (water condensation)
5. Outer planets were massive and drew in Hydrogen & Helium from gravitational attraction (atmosphere)

15. Interstellar cloud
Figure 7.8 A B

16. Condensation of dust grains
Figure 7.10

17. The birth of planets
Figure 7.11 A B

18. Craters on planets and moons
Figure 7.12
Diane
Mercury
Manicouagan Crater on Earth
Mars
Enceladus

19. Craters on planets and moons, continued
Figure 7.12
Tethys
Titania

20. Newly discovered planetary systems
Figure 7.13

21. Rules to be a “planet”
Orbit the Sun
Have enough Gravity to round it
Not be a satellite (orbit another nonstar body)
Dominate its own orbit*

22. Pluto falls short on the last one
Pluto falls short on the last one. Astronomers started finding bodies the same size as Pluto. They felt they had to limit the amount of planets. Our Solar System has eight. Pluto is a classified a dwarf planet.