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The Ordered Solar System

Ka Hana Imi Na auao A Science Careers Curriculum Resource Go to: www .cds.hawaii.edu/kahana

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Warm Up Questions

1. Which planet is bigger, Mercury or Jupiter ?

2. Are the gas giant planets closer to the Sun

than the rocky planets (yes/no)?3. How many planets are in the Solar System?

4. Is the Sun bigger, smaller, or the same sizeas the Moon?

5. What is the difference between the SolarSystem and the Milky Way Galaxy (just onesentence) ?

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Three types of objects orbit our Sun:

1. Planets

2. Dwarf Planets

Plutoids

3. Small solar system bodies

Why are there only 8 planets now?

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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 its the largest asteroid, the only dwarf planet in the asteroid belt.

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What is a Dwarf Planet?

Celestial body orbiting the Sun

Massive enough to be rounded by its

own gravity

BUT has NOT cleared its neighboring

region of planetesimals

Is not a satellite

A plutoid is a dwarf planet beyond the orbit

of Neptune

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Only 5 Dwarf Planets recognized so far but

there may be as many as 200

Pluto, approximate

true color

Ceres, seen through(Hubble telescope)

Haumea, with its 2 moons,

Hiiaka and Namaka

(Artists conception)

Makemake,(Artists conception)

Eris, seen through(Hubble telescope)

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Pacific Island Names for Planetary Objects

Haumea is theHawaiian goddessof childbirth andfertility.

The the moons"Hiiaka" and"Namaka arenamed after aftertwo of Haumea'sdaughters.

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Pacific Island Names for Planetary Objects

Makemake is thecreator of humanityin the mythos of theRapanui, the nativepeople of EasterIsland. The namechoice preserves

the planetaryobject's connectionwith Easter.

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3. What are Small Solar System Bodies?

Neither 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 gravity

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Terrestrial vs. Gaseous Planets

Terrestrial

Mercury, Venus,

Earth, Mars

1. Rocky

More dense

2. Smaller

3. More closely spaced

4. Closer to the Sun

Gaseous

Jupiter, Saturn,

Uranus, Neptune

1.Gaseous, has moreHe and H

Less dense (Saturn

would float)

2.Larger

3.Spaced farther apart

4.Farther from the Sun

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Terrestrial Planets

Venus

Mercury

Mars

From Nick Strobels Astronomy Notes at www.astronomynotes.com

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Jovian Planets, or Gas Giants

Jupiter

UranusNeptune

Saturn

From Nick Strobels Astronomy Notes at www.astronomynotes.com

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Do you see patterns or anomalies in these data?

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On which planet would youweigh the most?

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The Milky Way Galaxy

100,000 light years across1,000 light years thick

200 billion stars

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