1 The Ordered Solar System

2 Worksheet #1 Questions Look at the 4 groups formed on worksheet one. 1.Determine the characteristics of the planets included each group. (density, diameters, surface characteristics and avg. distance from the sun) 2.Compare the groups in terms of density, diameter, surface characteristics and avg. distance from the sun. 3.What might be a reason that Pluto is in its own group? Look at the 4 groups formed on worksheet one. 1.Determine the characteristics of the planets included each group. (density, diameters, surface characteristics and avg. distance from the sun) 2.Compare the groups in terms of density, diameter, surface characteristics and avg. distance from the sun. 3.What might be a reason that Pluto is in its own group?

Worksheet #2 Questions Look at the 3 groups formed on worksheet two: (Ice Moons, Small Ice Worlds, Rocky Moons) 1.Compare the groups in terms of density, diameter and distance from the Sun. 2.Does the distance from the Sun affect the location of a moon or planet on the graph? 3.How does the distance from the Sun affect the composition of the moon or planet? 3

4 Terrestrial vs. Gaseous Planets Terrestrial Mercury, Venus, Earth, MarsMercury, Venus, Earth, Mars 1.Rocky  More dense 2.Smaller 3.More closely spaced 4.Closer to the Sun Gaseous Jupiter, Saturn, Uranus, NeptuneJupiter, Saturn, Uranus, Neptune 1.Gaseous, has more He and H  Less dense (Saturn would float) 2.Larger 3.Spaced farther apart 4.Farther from the Sun

5 Terrestrial Planets Venus Mercury Mars From Nick Strobel’s Astronomy Notes at

6 Jovian Planets, or Gas Giants Jupiter Uranus Neptune Saturn From Nick Strobel’s Astronomy Notes at

7 Do you see patterns or anomalies in these data?

8 On which planet would you weigh the most?

9 Three types of objects orbit our Sun: 1.Planets 2.Dwarf Planets Plutoids Plutoids 3.Small solar system bodies Three types of objects orbit our Sun: 1.Planets 2.Dwarf Planets Plutoids Plutoids 3.Small solar system bodies Why are there only 8 planets now?

10 What is a planet? In August of 2007 the International Astronomical Union redefined what a planet is (no official scientific definition of a "planet" existed before). A planet: 1.Is a body that orbits the sun (this definition only applies to our Solar System) 2.Is large enough for its own gravity to make it round 3.And has "cleared its neighborhood" of smaller objects So a new the category of dwarf planet was created, which currently includes Pluto, Eris*, and Ceres**. *Eris is the largest known dwarf planet in the Solar System and the ninth largest body known to orbit the Sun. Its distance from the Sun is 97 AU. **Ceres is the smallest identified dwarf planet in the Solar System and, because it’s the largest asteroid, the only dwarf planet in the asteroid belt.

11 What is a Dwarf Planet? Celestial body orbiting the SunCelestial body orbiting the Sun Massive enough to be rounded by its own gravityMassive enough to be rounded by its own gravity BUT has NOT cleared its neighboring region of planetesimalsBUT has NOT cleared its neighboring region of planetesimals Is not a satelliteIs not a satellite Celestial body orbiting the SunCelestial body orbiting the Sun Massive enough to be rounded by its own gravityMassive enough to be rounded by its own gravity BUT has NOT cleared its neighboring region of planetesimalsBUT has NOT cleared its neighboring region of planetesimals Is not a satelliteIs not a satellite A plutoid is a dwarf planet beyond the orbit of Neptune

12 Only 5 Dwarf Planets recognized so far but there may be as many as 200 Pluto, approximate true color Pluto, approximate true color Ceres, seen through (Hubble telescope) Ceres, seen through (Hubble telescope) Haumea, with its 2 moons, Hi‘iaka and Namaka (Artist’s conception) Haumea, with its 2 moons, Hi‘iaka and Namaka (Artist’s conception) Makemake, Makemake, Eris, seen through (Hubble telescope) Eris, seen through (Hubble telescope)

13 Pacific Island Names for Planetary Objects Haumea is the Hawaiian goddess of childbirth and fertility. The the moons "Hi ʻ iaka" and "Namaka” are named after after two of Haumea's daughters. Haumea is the Hawaiian goddess of childbirth and fertility. The the moons "Hi ʻ iaka" and "Namaka” are named after after two of Haumea's daughters.

14 Pacific Island Names for Planetary Objects Makemake is the creator of humanity in the mythos of the Rapanui, the native people of Easter Island. The name choice preserves the planetary object's connection with Easter.

15 3. What are Small Solar System Bodies? Neither a planet nor a dwarf planetNeither a planet nor a dwarf planet All other objects orbiting the Sun All minor planets except dwarf planets Asteroids (except Ceres, the largest) Comets Not massive enough to be rounded by its own gravityNot massive enough to be rounded by its own gravity

16 The Milky Way Galaxy 100,000 light years across 1,000 light years thick 200 billion stars 100,000 light years across 1,000 light years thick 200 billion stars You are here