Overview of the Solar System

1. Overview of the Solar System • Solar system contents – one star, several planets, lots of debris.

2. Most of it is the Sun! • 99.8% of the mass of the Solar System resides in the Sun. • A hot ball of mostly hydrogen and helium held together by gravity. • In bulk composition it resembles an unbiased scoop of galactic material.

3. Most of it is the Sun! • 99.8% of the mass of the Solar System resides in the Sun. • A hot ball of mostly hydrogen and helium gas held together by gravity. • In bulk composition it resembles an unbiased scoop of galactic material. 3/4 Hydrogen 1/4 Helium 1% other elements

4. Eight Major Planets • Maybe one or two more depending on semantics and future discoveries.

5. Four Jovian Worlds • Jupiter, Saturn, Uranus and Neptune • “Gasballs” constituting 99.9% of the planetary mass

6. Four Jovian Worlds • Jupiter, Saturn, Uranus and Neptune • Hydrogen and helium, under high pressure, become dense liquids – more appropriately these are spinning liquid droplets.

7. Four Terrestrial Worlds • Mercury, Venus, Earth, and Mars • Small rocky/metallic worlds hugging the Sun with thin or non-existent atmospheres.

8. Jovian vs. Terrestrial Characteristics • Terrestrial: Mercury, Venus, Earth, and Mars • Small relatively speaking • Solid rocky cratered surfaces with significant iron cores • Three satellites between them all

9. Jovian vs. Terrestrial Characteristics • Jovian: Jupiter, Saturn, Uranus, Neptune – The “Gas Giants” • about 10 times bigger than the terrestrial worlds • Gaseous with no solid surface, resembling the Sun in composition (mainly Hydrogen and Helium) . • Clouds of Methane, Water, Ammonia, and other molecules provide an apparent “surface” • More than one hundred satellites – most made mainly of water/ice.

10. Jovian vs. Terrestrial Characteristics • Jovian: Interiors of compressed liquified gas

11. Jovian vs. Terrestrial Characteristics • Jovian: Cloudtop “surfaces”

12. Jovian vs. Terrestrial Characteristics • Jovian: Many satellites

13. Jovian vs. Terrestrial Characteristics • Jovian: Icy satellites

14. Jovian vs. Terrestrial Characteristics • Jovian: Satellites as big as planets, some with atmospheres.

15. Minor Constituents: Asteroids, Comets, and Dust • Asteroids: Millions of small rocky objects mostly between the orbits of Mars and Jupiter

16. Minor Constituents: Asteroids, Comets, and Dust • Asteroids: Millions of small rocky objects mostly between the orbits of Mars and Jupiter http://www.daviddarling.info/encyclopedia/A/asteroid.html

17. Minor Constituents: Asteroids, Comets, and Dust • Asteroids: Millions of small rocky objects mostly between the orbits of Mars and Jupiter

18. An Outer Icy Asteroid Belt • Another group of asteroid-sized bodies orbit beyond Neptune in the “Kuiper Belt” • Pluto is one of the largest of these.

19. A Cloud of Cometary Nuclei • Trillions of small iceballs, most only a kilometer in size, orbit as far out as ½ way to the nearest star. • only a small fraction make it into the inner solar system to be heated by the Sun to become a comet.

20. A Cloud of Cometary Nuclei • Trillions of small iceballs, most only a kilometer in size, orbit as far out as ½ way to the nearest star. • only a small fraction make it into the inner solar system to be heated by the Sun to become a comet.

21. Interplanetary Dust • The grinding of asteroids and evaporation of comets populates the inner solar system with fine dust. http://www.astrophoto.com/images.htm

22. Interplanetary Dust • The grinding of asteroids and evaporation of comets populates the inner solar system with fine dust.

23. Interplanetary Dust • The grinding of asteroids and evaporation of comets populates the inner solar system with fine dust.

24. Regular Features of the Solar System See orbits • All of the planets orbit the Sun in the same plane • All planetary orbits are nearly circular • All planets orbit the Sun in the same “direction” • Most planets rotate in the same sense as the orbit.

25. Regular Features of the Solar System • The Jovian and Terrestrial planets are well sorted in terms of distance from the Sun. • rocky worlds close – gaseous/icy worlds far away

26. Regular Features of the Solar System See orbits • All of the planets orbit the Sun in the same plane • All planetary orbits are nearly circular • All planets orbit the Sun in the same “direction” • Most planets rotate in the same sense as the orbit.

27. Regular Features of the Solar System • The Giant Planet satellite systems resemble the Solar System

28. Regular Features of the Solar System • Exposed solid surfaces are heavily cratered throughout the Solar System. • The process was messy and produced lots of leftovers.

29. Regular Features of the Solar System • Exposed solid surfaces are heavily cratered throughout the Solar System. • The process was messy and produced lots of leftovers.

30. Building a Solar System through “Accretion” • These regular features are “fossilized” memory of the conditions that gave rise to the Solar System. • In sum, they suggest the planets grew within a rotating flattened disk and, today, their orbits reflect the structure of that disk.