Sol ar Syst ems 1_

By: Chr i st i an Hassl er_

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As def i ned by t he I nt ernat i onal Ast ronomi cal Uni on, a pl anet i s a cel est i al body t hat …

a) I s i n orbi t around t he sun

b) has suf f i ci ent mass f or i t s sel f -gravi t y t o overcome r i gi d body f orces so t hat i t assumes a hydrost at i c equi l i br i um (near l y round) shape c) has cl eared t he nei ghborhood around i t s orbi t

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I s Eart h a pl anet ?

I s i t i n orbi t around t he sun?

Does i t have a near l y round shape?

Has i t cl eared t he area around i t ’s orbi t ?

Yes, Eart h i s a pl anet

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As def i ned by t he I nt ernat i onal Ast ronomi cal Uni on, a dwarf pl anet , l i ke a pl anet must …

a) Be i n orbi t around t he sun

b) have suf f i ci ent mass f or i t s sel f -gravi t y t o overcome r i gi d body f orces so t hat i t assumes a hydrost at i c equi l i br i um (near l y round) shape

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Unl i ke a pl anet , a dwarf pl anet must …

c) Have not cl eared t he area around i t s orbi t

d) not be a sat el l i t e

Satellite: a celestial body that orbits a planet

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I s t he moon a dwarf pl anet ?

I s i t i n orbi t around t he sun?

Does i t have a near l y round shape?

Has i t cl eared t he area around i t s orbi t ?

I s i t not a sat el l i t e?

No, t he moon i s not a dwarf pl anet

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I s Pl ut o a dwarf pl anet ?

I s i t i n orbi t around t he sun?

Does i t have a near l y round shape?

Has i t not cl eared t he area around i t s orbi t ?

I s i t not a sat el l i t e?

Yes, Pl ut o i s a dwarf pl anet

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Plutoids are dwarf planets in orbit around the Sun at a semi-major axis greater than that of Neptune

Thi s i s act ual l y si mpl er t han i t sounds…

Pl ut oi ds are def i ned t he same as dwarf pl anet s, except pl ut oi ds are f ound “out si de” of Nept une.

These are planets

These are dwarf planets

Dwarf planets to this side of Neptune are plutoids

Plutoids

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I s Ceres a pl ut oi d?

I s i t i n orbi t around t he sun?

Does i t have a near l y round shape?

Has i t cl eared t he area around i t s orbi t ?

I s i t not a sat el l i t e?

No, Ceres i s not a pl ut oi d

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I s i t i n orbi t around t he Sun at a semi -maj or axi s great er t han t hat of Nept une

What do pl anet s, dwarf pl anet s and pl ut oi ds have i n common?

They all have not cleared the area around their orbit.

They all must orbit the sun

Next SlidePl anet s, dwarf pl anet s, and pl ut oi ds al l must orbi t t he sun, ot herwi se t hey woul d be moons.

Where must pl ut oi ds be l ocat ed?

In the asteroid belt Beyond Neptune

Next SlidePl ut oi ds are dwarf pl anet s i n orbi t around t he Sun at a semi -maj or axi s great er t han t hat of Nept une