1. The
Solar
System

2. Light travels ~ 300,000 km/sec or
Our Solar System is about 16 billion km, or 10 billion miles, or 15 light hours across.
Light travels ~ 300,000 km/sec or
~1.1 billion km/hour

3. Our galaxy, the Milky Way

4. Solar System Formation

5. Your Parents’ Solar System

6. 21st Century Solar System

7. The 21st Century Solar System
Sun
Terrestrial Planets
Asteroid Belt
Jovian Planets
Kuiper Belt
Oort Cloud

8. The Solar System: List of Ingredients
Sun
Jupiter
Other planets
Everything else
Percent of total mass
99.8%
0.1%
0.05%

9. The Sun A middle-aged, average star: Shines because it is hot:
Mostly Hydrogen & Helium
Over 99% of the Solar System
~4.6 billion years old
Shines because it is hot:
Surface Temp ~6000 C
Mostly Visible, UV & IR light
Kept hot by nuclear fusion in its core:
Builds Helium from Hydrogen fusion.
Will shine for ~12 billion years

10. The Sun dominates the Solar System

11. Terrestrial Planets Mercury, Venus, Earth & Mars Rocky Planets:
“Earth-Like” Rocky Planets
Largest is Earth
Only in the inner solar system (0.4 to 1.5 AU)
Rocky Planets:
Solid Surfaces
Mostly Silicates and Iron
High Density: (rock & metal)
Earth, Venus, & Mars have atmospheres

12. The Terrestrial Planets
Mercury
(0.055 M)
Venus
(0.82 M)
Earth
(1 M)
Mars
(0.11 M)

13. The Jovian Planets Jupiter, Saturn, Uranus & Neptune
Largest Planets: at least 15 times mass of Earth.
Only in the outer solar system (5 to 30 AU)
No solid surfaces (mostly atmosphere)
Low density
Gas Giants: (Jupiter & Saturn)
Thick H/He atmosphere, liquid hydrogen mantle, ice core
Ice Giants: (Uranus & Neptune)
Ice/rock core & mantle, thin H/He atmosphere

14. The Jovian Planets Jupiter (318 M) Saturn (95 M) Uranus (15 M)
Neptune
(17 M)

16. Dwarf Planets Defined by the IAU in 2006 Dwarf Planets:
Ceres: first of the Asteroids, discovered in 1801
Pluto: trans-Neptunian object discovered in 1930
Eris: trans-Neptunian object discovered in 2005
Haumea (trans-Neptunian, suspected)
Makemake (trans-Neptunian, suspected)

17. Dwarf Planets

18. The Giant Moons
Moon: any natural satellite orbiting a planet or dwarf planet
Giant Moons:
Earth: The Moon (Luna)
Jupiter: Io, Europa, Ganymede, & Callisto
Saturn: Titan
Neptune: Triton
Many smaller moons, both rocky & icy.
Only Mercury & Venus have no moons.

19. The Giant Moons

20. Rhea
Iapetus
Titania
Oberon
Ceres
Tethys
Dione
Ariel
Umbriel
Charon
Pallas
Vesta
Hygeia
Mimas
Enceladus
Miranda
Proteus Io
Mercury
Europa
Moon
Triton
Titan
Ganymede
Callisto
Pluto

21. Kuiper Belt Class of icy bodies orbiting beyond Neptune. Examples:
Found only in the outer Solar System (>30AU)
Densities of 1.2 to 2 g/cc (mostly ices)
Examples:
Pluto & Eris (icy dwarf planets)
Kuiper Belt Objects (30-50AU)
Charon, Pluto’s large moon
Sedna & Quaor: distant large icy bodies

22. Kuiper Belt

23. Oort Cloud Spherical cloud of comets.
Extends out to almost 50,000 AU (1 light-year)
May contain trillions of comets
The outer edge is the farthest reach of the Sun’s gravitational pull.
There are no confirmed observations – its existence is theoretical only.

24. Oort Cloud

25. The Leftovers (small bodies)
Asteroids:
Made of rock & metal (density 2-3 g/cc)
Sizes: Few 100km to large boulders (big)
Most are found in the Main Belt ( AU)
Meteoroids:
Bits of rock and metal (little)
Sizes: grains of sand to boulders
Comets:
Composed of rock & ice
Longs tails of gas & dust are swept off them when they pass near the Sun.

26. Asteroids
951 Gaspra
243 Ida
253 Mathilde

27. Meteor burning up in the
atmosphere.

28. Comet P/Halley
Comet P/Wilt

30. Is Pluto a Planet? What to consider? Size? Shape? Orbit?
What is it made of?

31. IAU Definition of a Planet
In 2006, the International Astronomical Union (IAU) came up with the following definition of a planet:
orbits the Sun
has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape (i.e., it is spherical),
has cleared the neighborhood around its orbit,
is not a satellite

32. IAU Definition of a Dwarf Planet
In 2006, the International Astronomical Union (IAU) came up with the following definition of a dwarf planet:
orbits the Sun
has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape (i.e., it is spherical),
has not cleared the neighborhood around its orbit,
is not a satellite

33. The Size and Distance Scale Of The Solar System
In turn, the size of our Solar System is very large compared to the size of our Earth, or even the largest planet, Jupiter.
The distance from our Earth to the Moon is about 238,000 miles or 384,000 kilometers (nearly 100 times Earth’s diameter, or about 30 times the distance around the Earth at its equator).
The distance from our Earth to the Sun is about 93,000,000 miles or 149,600,000 kilometers (more than 390 times the distance to the Moon).
The most distant major planet from the Sun, Neptune, is 30 times Earth’s distance from the Sun.
The nearest stars in our Galaxy, the star system of Alpha Centauri, is 9,000 times Neptune’s distance from the Sun!

34. SIZES AND DISTANCES IN THE SOLAR SYSTEM
Diameters of Solar System Members:
Sun = 1,392,000 km
Mercury = 4,878 km
Venus = 12,104 km
Earth = 12,756 km
Mars = 6,794 km
Jupiter = 142,984 km
Saturn = 120,536 km
Uranus = 51,118 km
Neptune = 49,530 km
Pluto = 2,304 km
Mean Distance from Sun
57,900,000 km = AU
108,200,000 km = AU
149,600,000 km = AU
227,900,000 km = AU
778,300,000 km = AU
1,427,000,000 km = AU
2,871,000,000 km = AU
4,497,000,000 km = AU
5,914,000,000 km = AU
Earth’s Moon = 3,476 km Mean Distance from Earth = 384,400 km

35. Earth and Moon to Scale

36. Sizes and Distances in the Earth-Moon System

37. Relative Sizes of Planets in Our Solar System

38. The Planets of Our Solar System
The Inner Planets
Sizes to Scale
Mercury Venus Earth and Moon Mars

39. The Planets of Our Solar System
The Outer Planets
Jupiter
Saturn
Earth Included for Scale.
Uranus
Pluto
Neptune

40. Size Comparisons In Our Solar System

41. THE SIZE AND DISTANCE SCALE OF THE SOLAR SYSTEM
The distances between the members of our Solar System are much larger than the sizes of the members (even the Sun).
The distance from the Earth to the Sun is about 150,000,000 km (about 93,000,000 miles) in comparison to the Sun’s diameter of about 1,392,000 km (about 110 times that of Earth).
The largest planet, Jupiter, is 5 times Earth’s distance from the Sun, and 11 times Earth’s diameter (1/10 of the Sun’s diameter).
The most distant major planet, Neptune, is 30 times Earth’s distance from the Sun.
The region beyond the orbit of Neptune, called the Kuiper Belt, contains a large number of smaller objects (including Pluto and at least one recently discovered slightly larger object), all (as yet known) smaller than our Moon.
The Kuiper Belt objects known to date can reach distances of more than 90 times Earth’s distance from the Sun.

42. SIZES AND DISTANCES IN THE SOLAR SYSTEM
Diameters of Solar System Members:
Sun = 1,392,000 km
Mercury = 4,878 km
Venus = 12,104 km
Earth = 12,756 km
Mars = 6,794 km
Jupiter = 142,984 km
Saturn = 120,536 km
Uranus = 51,118 km
Neptune = 49,530 km
Pluto = 2,304 km
Mean Distance from Sun
57,900,000 km = AU
108,200,000 km = AU
149,600,000 km = AU
227,900,000 km = AU
778,300,000 km = AU
1,427,000,000 km = AU
2,871,000,000 km = AU
4,497,000,000 km = AU
5,914,000,000 km = AU
Earth’s Moon = 3,476 km Mean Distance from Earth = 384,400 km

43. Orbits of the Inner Planets

44. Orbits of Jupiter and Saturn

45. Orbits of the Outer Planets