WHAT’S THAT UP IN THE SKY???The difference between

Comets, Meteors and Asteroids

COMETS, ASTEROIDS, AND METEORS

COMETS AND ASTEROIDS

Comets………Dirty Balls of Ice They look like a

star with a ghostly white

tail.

The term "comet"

derives from the Greek

aster kometes,

which means "long-haired

star"---a reference to

the tail.

Comets………Dirty Balls of IceThey can be seen by us only

when they pass by the sun and the sun’s heat melts them.

The comet's tail is made of material from the comet;

gas from the ices and dust that

is mixed in with the ice. They escape as the comet

melts.The tail always points away

from the sun due to the solar winds (movement of

heat away from sun)

They travel around the sun in long looping orbits that bring them near

the sun on one end and around Jupiter on the other end.

Example:

If a comet has a large orbit, it takes a long time to go around the Sun. Some comets are "short-period"

comets that take five or ten years to complete an orbit. Some comets are "long-period" comets that take decades, centuries, or millenia to

orbit the Sun.

Comets………Dirty Balls of IceThe icy, hard part of the comet is

called the nucleus. As the comet melts, sometimes large chunks of ice break off in a hurry and large amounts of gases escape at once and cause a bright “outburst”.

The gas and dust are released and form an atmosphere around the

comet called the coma.

After 500 or so passes near the

Sun, most of a comet's ice and gas

is lost - leaving a

rocky object very much

like an asteroid in appearance

.

Asteroids……Rockin’ AroundAsteroids are

LARGE chunks of rock and

metal that orbit the sun.

They range from just over ½ a

mile (1km) to a few hundred

miles in diameter

(diameter = how wide across)

Most asteroids travel in the

wide gap between the inner planets

and outer planets

(between Mars and Jupiter).

But a few travel in paths across Mar’s orbit and

some even cross in Earth’s

orbit.

Most of the chunks or rock and metal in space came together long ago to form the planets and moons.

Asteroids are left-over

pieces of rock from when the solar system was formed.

How are meteorites related to asteroids?

Meteorites are pieces of asteroids - or sometimes

planets or the Moon.

Key Questions: 1.Has Earth ever been hit by a comet or an asteroid? If yes, how have such impacts affected Earth?

2.How often does a comet or an asteroid hit Earth?

Module 3 Activity 1: (Simulation Activity)

What happens when a comet or an asteroid hits Earth?

Main objective - describe how impact craters are formed when a comet or asteroid hits Earth, based on a simulation

QUESTIONS:Q1. What do you notice about the shape of your pebble’s crater and

the shape of the impact crater shown in the photo?

Q2. What do you think happened to the plants and animals living in

the area where the comet or asteroid crashed?

Q3. Which is most likely to make a more frequent “visitor” of Earth: a comet or an asteroid? Why do you

think so?

How does the Comet or asteroid hit Earth?

Barringer’s Crater

An iron meteorite 100 feet across and 70,000 tons slamed into the Earth at about

43,000mph in the Arizona desert near Flagstaff 40,000 years ago. Barringer Crater is

4,100 feet wide and 571 feet deep.

Key Ideas

Some comets and asteroids may become Near-Earth Objects as they orbit the Sun.

Other planets in the Solar System (gravity) are believed to affect the NEOs’ orbits, thus they crashed into Earth.

Comets and asteroids have hit

Earth in the past.

An impact crater is formed on the ground where a comet, asteroid, or their fragments hit Earth's surface.

Large-scale impacts changed the physical geography of the

surrounding, killed living creatures in the surrounding area, and most probably caused global climate

change (e.g., ice age).

Comets and asteroids have similarities and differences (Table 1). Their major differences are in their origin and composition.

Meteoroid, meteor, and

meteorite: How are they related?

Q1. What is a meteor?

Answer:

A meteor is a light phenomenon or a streak of light as observed from Earth when a meteoroid passes through Earth’s atmosphere.

Q2. What is a meteoroid?

A meteoroid is a fragment from a

comet, an asteroid, Moon, or even Mars that orbits around the Sun, following the orbit of its parent or source.

What celestial (space) objects can a meteoroid

come from?

Answer: Meteoroids can come from comets, asteroids, the Moon, and Mars.

What causes a meteor?

Answer:

A meteor is observed when a meteoroid

passes through Earth’s atmosphere and burns up in the

process.

Why does a meteor shower occur?

Answer A meteor shower happens

when Earth passes through the orbit of a comet (or an

asteroid) where fragments and dust remain in orbit and orbits

the Sun as well while Earth goes around the Sun. Since

there are more dust and fragments, there are more

meteoroids that may burn up in Earth’s atmosphere as Earth passes the orbit of the parent

comet or asteroid.

What have we learned?• Why is there an

asteroid belt? Orbital resonances with

Jupiter disrupted the orbits of planetesimals, preventing them from accreting into a planet. Those that were not ejected from this region make up the asteroid belt today. Most asteroids in other regions of the inner solar system accreted into one of the planets.

• How are meteorites related to asteroids?

Most meteorites are pieces of asteroids. Primitive meteorites are essentially unchanged since the birth of the solar system. Processed meteorites are fragments of larger asteroids that underwent differentiation.

Comets and asteroids may break apart while orbiting

the Sun. These smaller fragments are called

meteoroids.

Rock fragments coming from the Moon,

Mars, and other planets are also called

meteoroids.

The meteoroid burns as it enters Earth’s

atmosphere. Surviving fragments that land on

Earth are called meteorites.

Meteor and meteor showers are light

phenomena.

Meteors…Shooting Stars or Space Garbage

Meteors are also called shooting stars

Meteors are small pieces of space debris (junk)

pulled into Earth’s atmosphere by gravity.

Meteorites are metallic rocks broken off from asteroids and comets

Meteors fall to Earth at speeds from 22,000

MPH to 64,000 MPH (8x shuttle speed)

You Can Buy Meteors-

Most meteors are only as big as a grain of sand.

Most burn up while entering Earth’s Atmosphere

However………………They can be bigger. Craters in the Earth and ones studied below the surface show that one about the size of a house landed about 250,000 years ago! Is that what killed the dinosaurs???

Meteors are falling all the time.

On a clear, dark night you may see one.

During the annual meteor storms, you may see 100 per hour.

How can something as small as a grain of sand light up so

brightly?

Entering the Earth’s atmosphere so fast creates a lot of friction.

The friction causes them to heat up and give off light.

The light trail may stay in the sky for up to 30 minutes and

end with a “POP”.REALLY bright meteors are called

FIREBALLS

What’s That Up In The Sky???

COMETS ASTEROIDS METEORS

Made of ice-have tails

Made of rock and metal

Made of rock and metal

Stay in space Stay in space Fall into Earth’s atmosphere

Orbit the sun Orbit the sun Gravity pulls to Earth; they burn up as they fall