Small Bodies of the Solar System

Small Bodies of the Solar System

Middle School

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Learning Objectives

• Define and differentiate between asteroids, comets, and meteors.

• Explain the criteria for a dwarf planet and why Pluto is one.

• Describe the location and composition of the asteroid belt, Kuiper belt, and Oort cloud.

• Distinguish between a meteoroid, a meteor, and a meteorite.

Key Vocabulary

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Asteroid

A small, irregular rock body orbiting the Sun, often called a minor planet by scientists.

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Comet

A small, icy object that orbits the Sun and develops a tail as it approaches it.

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Meteor

A small piece of matter that burns up upon entering Earth’s atmosphere, creating a shooting star.

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Dwarf Planet

A celestial body orbiting a star that is spherical but has not cleared its orbital path.

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Asteroid Belt

A torus-shaped region in the Solar System, located roughly between Mars and Jupiter.

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Kuiper Belt

A circumstellar disc in the outer Solar System, extending from the orbit of Neptune.

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What Are Asteroids?

• Asteroids are small, irregular rocks made of metal and rock that orbit the Sun.

• They are leftover materials from when our solar system first formed long ago.

• Most are in the Asteroid Belt, a region between Mars and Jupiter.

• Scientists watch Near-Earth asteroids whose orbits are close to our planet’s path.

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Multiple Choice

What are asteroids primarily made of, and where are most of them located?

• Rock and metal; located in the asteroid belt between Mars and Jupiter.

• Ice and dust; located in the Oort cloud.

• Organic compounds; located in Earth's orbit.

• Gas and ice; located beyond Neptune.

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All About Comets

Short-Period Comets

• Comets are small celestial bodies made of ice, dust, and small rocky particles.

• They take less than 200 years to complete one orbit around the Sun.

• These comets originate from the Kuiper Belt, a region beyond the planet Neptune.

Long-Period Comets

• These comets take thousands or millions of years to complete a single orbit.

• They come from the Oort Cloud, a distant, spherical cloud of icy objects.

• The Oort Cloud is located in the outermost region of our solar system.

Multiple Choice

Where do short-period comets that take less than 200 years to orbit the Sun mainly come from?

• The asteroid belt

• The Kuiper Belt

• The Oort Cloud

• Between Earth and Mars

Meteoroids, Meteors, and Meteorites

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Meteoroids

• ​Meteoroids are small rocks or particles of debris in the solar system.

• ​​They are often broken-off pieces of comets or asteroids.

• ​They are found floating and drifting throughout our solar system.

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Meteors

• ​A meteor is the bright streak of light in the sky.

• ​​It is commonly known as a 'shooting star' when you see one.

• ​This happens when a meteoroid burns up in Earth’s atmosphere.

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Meteorites

• ​A meteorite is the remaining piece of a meteoroid that survives.

• ​​It passes through the atmosphere without burning up completely.

• ​This is the space rock that actually lands on Earth's surface.

Multiple Choice

A small rock that survives its journey through the atmosphere and lands on Earth's surface is called a...

• Meteor

• Meteoroid

• Comet

• Meteorite

Dwarf Planets

• A dwarf planet hasn't cleared other objects from its orbit.

• Pluto is a dwarf planet in the Kuiper Belt.

• Other dwarf planets are Ceres, Makemake, Eris, and Haumea.

Multiple Choice

Why is Pluto classified as a dwarf planet?

• Because it is smaller than Earth's moon.

• Because it does not orbit the Sun.

• Because it is not spherical.

• Because it has not cleared its orbit of other objects.

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Common Misconceptions

Misconception	Correction
Pluto is no longer part of the solar system.	Pluto is now classified as a dwarf planet in our solar system.
‘Shooting stars’ are actual stars.	They are meteors burning up in our atmosphere.
The asteroid belt is a crowded field of asteroids.	The distance between asteroids is vast, so spacecraft can pass through safely.
Comets always have a visible tail.	Comets only form tails when they get close to the Sun.

Multiple Choice

What is the primary difference between a planet and a dwarf planet?

• A dwarf planet does not orbit the sun.

• A dwarf planet is not large enough to be spherical.

• A planet is made of rock, while a dwarf planet is made of ice.

• A planet has cleared its orbit of other objects, while a dwarf planet has not.

Multiple Choice

A scientist observes a celestial body with a period of 150 years that originates from beyond Neptune. How would this body be classified?

• A Near-Earth asteroid.

• An asteroid from the Asteroid Belt.

• A short-period comet from the Kuiper Belt.

• A long-period comet from the Oort Cloud.

Multiple Choice

If a large celestial object, spherical in shape, is discovered orbiting the Sun within the Kuiper Belt alongside many other small, icy bodies, how would scientists most likely classify it and why?

• As a dwarf planet, because it has not cleared its orbital path.

• As a comet, because it is located in the Kuiper Belt.

• As an asteroid, because it is a small celestial object.

• As a planet, because it is spherical and orbits the Sun.

Multiple Choice

A geologist finds a rock on Earth containing rare minerals and evidence of formation in a zero-gravity environment. What is the most probable origin of this rock?

• It is a rock originating from Earth's mantle.

• It is a piece of a comet that burned up completely.

• It is a meteorite from an asteroid or other space debris.

• It is a meteoroid that is still in space.

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Summary

• Asteroids are rocky bodies found in the asteroid belt, while comets are icy bodies with tails.

• A meteoroid becomes a meteor in our atmosphere and a meteorite if it lands on Earth.

• Dwarf planets are spherical bodies that orbit the Sun but have not cleared their orbital path.

• Studying these small bodies helps us understand how our solar system was formed.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

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