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 Barringer Meteorite Crater

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