Meteoroids! Asteroids! Comets!

Oh, my!
What makes up our Solar System?
The sun
Planets
Moons
Asteroid belt (between Mars and Jupiter)
Lots of space
All sorts of bits and pieces of rock
Meteorite, Meteoroid, Meteor? What’s the difference?
Meteorite vs. Meteoroid
Meteoroid = while in space a meteorite is called a meteoroid
Meteorite = a small rock or rocky grain that strikes Earth’s surface

So the difference is just based on where the rock is when you are describing it
Meteor
Sometimes called a “Shooting Star”
When a meteorite enters Earth’s atmosphere, friction causes them to burn up, producing a streak of light
Where do they come from?How big are they?
Pieces of rock that broke off other objects
Sizes range from as small as a pebble or as big as a huge boulder
Are they dangerous?
Most meteoroids disintegrate before reaching the earth by burning up in Earth’s atmosphere
Some leave a trail that lasts several minutes
Meteoroids that reach the earth are called meteorites. Large ones can cause damage
Flagstaff, Arizona
49,000 years ago
Meteorite about 150 feet in diameter
Weighed 650 pounds
Energy = 2.5 million tons of dynamite
4000 feet wide, 650 feet deep
Still visible today
What’s a “Meteor Shower”?
Usual rate = six meteors per hour
During a Meteor Shower = rate may be as high as 60 meteors per hour
Occur when Earth passes through the tail or debris of a comet
Presides (mid-August)
Leonids (mid-November)

Comets
Bodies in space made up of ice, dust, small gritty particles
Sometimes called “dirty snowballs”
When close to the sun, ice vaporizes, producing a spectacular streak of gas, referred to as a “tail”
Many in a regular orbit around the sun
Comets
Where do comets come from?
Many ordinate in a region called the Oort cloud which is located beyond the orbit of the dwarf planet Pluto

Others originate in the Kuiper Belt beyond the orbit of Neptune

This region is filled with billions of comets

Famous Comets
Comet Hale-Bopp

Halley’s Comet

Comet Kohoutek

A Comet’s Tail
Asteroids
An irregularly shaped rocky object in space (like a space potato)
May be the shattered remains of objects left over from the time when the planets were formed
How big are asteroids?
Larger than meteoroids
(In fact, the main difference between meteoroids and asteroids is their size.)

Size ranges from 10 feet across to bigger than a mountain

Asteroids
Approx. 150,000 asteroids in the Solar System
Most are in a band that orbit the sun between Mars and Jupiter (Asteroid Belt)
Why are there all of those asteroids between Mars and Jupiter and not another planet?
Near-Earth Asteroids (NEAs)
At least 1000 asteroids orbit outside of the Asteroid Belt – these could be a danger to Earth
Asteroids that cross Earth’s orbit are called Near-Earth Asteroids or NEAs
NEA / Earth collision not likely
But if it did, the affect of the impact would depend on the size of the asteroid
Large Asteroid hits Earth 65 Million Years Ago
Catastrophic Collision
Asteroid 6 to 12 miles in diameter
Near the Yucatan Peninsula in the Gulf of Mexico
Large Asteroid hits Earth 65 Million Years Ago
Collision produced an explosion = 100 trillion tons of dynamite
Gouged out a crater about 60 miles in diameter
How would an event like this affect Earth?
What do Scientists Think Happened?
Forests were wiped clean for a distance of 300 to 600 miles in all directions
300 foot wave struck the coast of Texas
Powerful Earthquakes
Landslides destroyed long stretches of coastline

What do Scientists Think Happened
Explosion threw huge amounts of debris into the air, covering large parts of North America
Poisonous gases and dust soared high into the atmosphere, spread over most of the Earth, and then fell back onto the Earth’s surface
What do Scientists Think Happened
Sunlight was blocked from reaching the Earth’s surface for many months
Temperatures plummeted to the freezing point in normally warm areas
Not enough sunlight for photosynthesis
Plants died . . . Animals died
Many animals became extinct (including many types of dinosaurs)
The Rise and Fall of Life on Earth
See the dip around 65 Million years ago?
This represents the extinction of about 75% of all the species alive at that time.
Is the Earth in danger of a large asteroid impact?
Not that we know of!
None of the asteroids or comets discovered so far is on a collision course with Earth.
However, we can't speak for those that are not yet discovered. In principle, one of those could hit any time, but statistically the chances are very small.
Torino Scale
A system used to rate the hazard level of an object moving toward Earth
Review
Q: What is the difference between a meteoroid, meteororite, and a meteor?

Meteoroid = while in space a meteorite is called a meteoroid
Meteorite = a small rock or rocky grain that strikes Earth’s surface
Meteor = “Shooting Star”
Review
Q: What is the difference between an asteroid and a meteoroid?
The main difference is the size of the object.

Q: Which is larger, asteroid or meteoroid?
Asteroids are larger than meteoroids.
Review
Q: Why is it important to study smaller bodies in our Solar System such as comets or asteroids?

They help us learn about the history of our Solar System.
Review
Q: Why do planets and moons with atmospheres have less impact craters than those without atmospheres?

The atmosphere slows and burns smaller objects like meteorites, thus many do not reach the surface to create an impact.
Review
Bright streaks of light that result when rocky bodies burn up in the atmosphere are called ___________.
Frozen bodies made of ice, rock, and dust, sometimes called “dirty snowballs” are called _____________.
Small, rocky bodies that revolve around the sun are called ______________.
Review
Bright streaks of light that result when rocky bodies burn up in the atmosphere are called meteors.
Frozen bodies made of ice, rock, and dust, sometimes called “dirty snowballs” are called comets.
Small, rocky bodies that revolve around the sun are called asteroids.

Review
Q: Discus what could happen if the Earth experienced another large asteroid impact. How would it affect life on Earth?

Forests flattened for many miles
If asteroid landed in water, it would cause giant waves and landslides
Powerful Earthquakes
The devastation continues…
Poisonous gases and dust fills the atmosphere, blocks out the sun
Temperatures drop drastically
No photosynthesis = plants die = animals die
Some animals become extinct

Review
Q: Where is the Asteroid Belt?
Asteroid Belt is between Mars and Jupiter

Q: What is the Torino Scale?
A system used to rate the hazard level of an object moving toward Earth

Mountain Top
Meteoroids! Asteroids! Comets!

Oh, my!
What makes up our Solar System?
The sun
Planets
Moons
Asteroid belt (between Mars and Jupiter)
Lots of space
All sorts of bits and pieces of rock
Meteorite, Meteoroid, Meteor? What’s the difference?
Meteorite vs. Meteoroid
Meteoroid = while in space a meteorite is called a meteoroid
Meteorite = a small rock or rocky grain that strikes Earth’s surface

So the difference is just based on where the rock is when you are describing it
Meteor
Sometimes called a “Shooting Star”
When a meteorite enters Earth’s atmosphere, friction causes them to burn up, producing a streak of light
Where do they come from?How big are they?
Pieces of rock that broke off other objects
Sizes range from as small as a pebble or as big as a huge boulder
Are they dangerous?
Most meteoroids disintegrate before reaching the earth by burning up in Earth’s atmosphere
Some leave a trail that lasts several minutes
Meteoroids that reach the earth are called meteorites. Large ones can cause damage
Flagstaff, Arizona
49,000 years ago
Meteorite about 150 feet in diameter
Weighed 650 pounds
Energy = 2.5 million tons of dynamite
4000 feet wide, 650 feet deep
Still visible today
What’s a “Meteor Shower”?
Usual rate = six meteors per hour
During a Meteor Shower = rate may be as high as 60 meteors per hour
Occur when Earth passes through the tail or debris of a comet
Presides (mid-August)
Leonids (mid-November)

Comets
Bodies in space made up of ice, dust, small gritty particles
Sometimes c

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