Bellwork Review Questions: Ch 4

1. What is a planet and how is it formed? (think of the video we watched “How Universe was Made”)

2. How do we know how the solar system formed?

3. What does an astronomical unit measure?

4. Why is Pluto now considered a Dwarf Planet?

A look at our nearest neighbor in Space!

LESSON 2

The Moon

Free powerpoints at http://www.worldofteaching.com

What is the Moon?

• A natural satellite• One of more than 96 moons in

our Solar System• The only moon of the planet

Earth

Location, location, location!

• About 384,000 km (240,000 miles) from Earth

• 3,468 km (2,155 miles) in diameter (about ¼ the size of Earth)

The Moon’s Surface

• No atmosphere• No liquid water• Extreme

temperatures– Daytime = 130C

(265°F)

– Nighttime = -190C (-310 F)

• 1/6 Earth’s gravity

Lunar Features - Highlands

• Mountains up to 7500 m (25,000 ft) tall

• Rilles (trenchlike valleys)

Lunar Features - Craters• Up to 2500 km (1,553 miles) across

• Most formed by meteorite impact on the Moon

• Some formed by volcanic action inside the Moon

Lunar Features - Maria

• Originally thought to be “seas” by early astronomers

• Darkest parts of lunar landscape

• Filled by lava after crash of huge meteorites on lunar surface 3-4 billion years ago

• Mostly basalt rock

Maria

Craters

Can you see the rays?

Does this photo show us a limb or terminator line?

Movements of the Moon

• Revolution – Moon orbits the Earth every 271/3 days

• The moon rises in the east and sets in the west

• The moon rises and sets 50 minutes later each day

• Rotation – Moon turns on its axis every 27 days

• Same side of Moon always faces Earth

Name these features.

Name these

features.

Craters

Maria

Kuiper Belt

_______________

Oort Cloud

National Aeronautics and

Space Administration

Educational Product

Teachers Grades 5-12

Exploring Meteorite Mysteries

Slide Set with Script

Larger meteorites Larger meteorites are extremely rare, are extremely rare,

but make but make enormous craters enormous craters when they hit the when they hit the

EarthEarth

It was formed It was formed about 50,000 years about 50,000 years ago when a large ago when a large iron meteorite hit iron meteorite hit

the Earththe Earth

Scientists Scientists estimate that the estimate that the

meteorite weighed meteorite weighed one million tonsone million tons

Meteor Crater in Arizona is Meteor Crater in Arizona is over one kilometer across and over one kilometer across and

150 meters deep150 meters deep

Although people have Although people have seen meteorites fall seen meteorites fall

since the earliest since the earliest times, it was only times, it was only about 1800 when about 1800 when scientists finally scientists finally

became convinced that became convinced that rocks really did fall rocks really did fall

from the skyfrom the sky

Since then, we've Since then, we've discovered that most discovered that most meteorites come from meteorites come from the asteroid belt, the the asteroid belt, the

area of the solar area of the solar system between the system between the orbits of Mars and orbits of Mars and

Jupiter where many Jupiter where many asteroids orbit the sunasteroids orbit the sun

Asteroids are small Asteroids are small planets, fragments of planets, fragments of rock and iron left over rock and iron left over

from the formation of the from the formation of the solar system or the solar system or the breakup of larger breakup of larger

fragmentsfragments

Many asteroids Many asteroids probably look like Ida, probably look like Ida,

the asteroid in this the asteroid in this picture taken by the picture taken by the Galileo spacecraft in Galileo spacecraft in

19931993

Ida is about 30 Ida is about 30 kilometers long, is made kilometers long, is made

of rock, and has many of rock, and has many craterscraters

Comets are small bodies Comets are small bodies made of rock, dust and made of rock, dust and

ice, formed in the distant ice, formed in the distant reaches of the solar reaches of the solar

systemsystem

Then solar radiation Then solar radiation heats the comet's surface, heats the comet's surface, causing part of the ice to causing part of the ice to

boil off into space and boil off into space and carry some of the dust carry some of the dust

with itwith it

When this happens the When this happens the comet can develop a "tail" comet can develop a "tail"

millions of kilometers millions of kilometers long, and leave a dust long, and leave a dust

trail behind in solar orbittrail behind in solar orbit

Which finally cleared out to leave just the Sun & Planets (and their moons, etc.)

Formation of the Solar System

It began with a Nebular Gas CloudFrom which developed Proto-Sun & Planets

Debris

Rocky Matter(Source of craters)

Icy Matter (Source of comets)

From which came the Sun, Planets, & Debris

Icy Matter ...

Jan Oort’s Cometary Cloud

Most comets that we see today are believed to have come from the Oort cloud.

Why do you suppose they leave the cloud in the first place?

Nucleus - Few 10’s of kmComa -

May be 1000’s of km

The Head of a Comet

The Tail may be Millio

ns of km

The Tail of a Comet

Very few asteroid pieces get the chance to Very few asteroid pieces get the chance to travel that fartravel that far

Most asteroids never do, and spend eternity Most asteroids never do, and spend eternity in space, quietly orbiting the Sunin space, quietly orbiting the Sun

Larger Larger

meteormeteorites ites

don't don't come come

from from comets comets

but but from from

asteroiasteroidsds

It's a It's a long long way way from from the the

asteroiasteroid belt d belt to the to the EarthEarth

Every now and again the Every now and again the orbits of asteroids cross and orbits of asteroids cross and

their quiet times endtheir quiet times end

Then the asteroids collide Then the asteroids collide and shatter, and the pieces and shatter, and the pieces

fly into different orbits around fly into different orbits around the sun the sun

Some of these pieces orbit Some of these pieces orbit closer and closer to the suncloser and closer to the sun

Eventually some of their Eventually some of their orbits cross the Earth's orbit, orbits cross the Earth's orbit, and the piece of asteroid can and the piece of asteroid can

hit the Earthhit the Earth

We see this moving We see this moving flame as a meteor flame as a meteor crossing the sky crossing the sky

If the asteroid fragment If the asteroid fragment is big enough, fist-sized is big enough, fist-sized or so, it won't burn up or so, it won't burn up

completely and will fall to completely and will fall to the Earth as a meteorite the Earth as a meteorite

These small meteorites These small meteorites do not explode or make do not explode or make craters when they hit craters when they hit

They just hit like an They just hit like an extra large hailstone or a extra large hailstone or a rock thrown from across rock thrown from across

the streetthe street

The dinosaurs were The dinosaurs were killed 65 million years killed 65 million years

ago after a huge ago after a huge meteorite hit the Earthmeteorite hit the Earth

The explosion caused The explosion caused great storms and great storms and

waves, and the sky was waves, and the sky was dark for months with dark for months with

dust and ashdust and ash

The dinosaurs, along The dinosaurs, along with many other with many other

animals and plants, animals and plants, were probably killed by were probably killed by

the climate changes the climate changes that followed the that followed the

explosionexplosion

Meteorites have also had Meteorites have also had devastating effects on life...devastating effects on life...

Inner Planets

Outer Planets

What are rings?

What is an orbit?

Describe the shape of an orbit.