Solar System 1

Solar Systems 1_

By: Christian Hassler_

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As defined by the International Astronomical Union, a planet is a celestial body that…

a) Is in orbit around the sun

b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape c) has cleared the neighborhood around its orbit

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Is Earth a planet?

Is it in orbit around the sun?

Does it have a nearly round shape?

Has it cleared the area around it’s orbit?

Yes, Earth is a planet

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As defined by the International Astronomical Union, a dwarf planet, like a planet must…

a) Be in orbit around the sun

b) have sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape

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Unlike a planet, a dwarf planet must…

c) Have not cleared the area around its orbit

d) not be a satellite

Satellite: a celestial body that orbits a planet

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Is the moon a dwarf planet?

Is it in orbit around the sun?

Does it have a nearly round shape?

Has it cleared the area around its orbit?

Is it not a satellite?

No, the moon is not a dwarf planet

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Is Pluto a dwarf planet?

Is it in orbit around the sun?

Does it have a nearly round shape?

Has it not cleared the area around its orbit?

Is it not a satellite?

Yes, Pluto is a dwarf planet

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

This is actually simpler than it sounds…

Plutoids are defined the same as dwarf planets, except plutoids are found “outside” of Neptune.

These are planets

These are dwarf planets

Dwarf planets to this side of Neptune are plutoids

Plutoids

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Is Ceres a plutoid?

Is it in orbit around the sun?

Does it have a nearly round shape?

Has it cleared the area around its orbit?

Is it not a satellite?

No, Ceres is not a plutoid

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Is it in orbit around the Sun at a semi-major axis greater than that of Neptune

What do planets, dwarf planets and plutoids have in common?

They all have not cleared the area around their orbit.

They all must orbit the sun

Next SlidePlanets, dwarf planets, and plutoids all must orbit the sun, otherwise they would be moons.

Where must plutoids be located?

In the asteroid belt Beyond Neptune

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