Earth is our home, and it will probably be our only home for a while.

Transcription

1 0 How is it we can take pictures of a planet illions of iles away? First, because we live on Earth. Earth is a special place. We can breathe its air and drink its water. We re able to live here. The weather changes here, but not as horribly as it does on any other planet in the solar syste. There is no planet you could live on for even a inute except Earth without a protective spaceship or spacesuit. On no planet we know of would you find air you could breathe, liquid water, or even other living things big enough to see with your eyes. It does not look like huan beings could live on any planet in this solar syste except Earth, even if we could get to one. What does this all ean? Earth is our hoe, and it will probably be our only hoe for a while. How well do you know your own hoe? Well, if we re talking about the house that you live in, you probably know it pretty well. You probably know where each roo is. You know where the light switches are. You know how to get water running in a sink or tub. You know how to get around and what to expect. Earth is not as si as your house, no atter how strange and interesting your house ay be. Any one syste on Earth is far ore cox than any hoe. Just trying to understand how a si rock is ade can take years of study. And we have systes on our planet that we siply do not fully understand, such as our weather. We know a lot about weather, but we also know that there s a lot ore to know. This is why the TV weather person can get their predictions wrong fro tie to tie. They ll tell you rain in the afternoon, you get out your ubrella and it s sunny that afternoon. This happens a lot. It happens because we do not know all the things that happen on Earth that can ake or change weather. What we do know is that Earth is a planet. Everything here is help on to the planet and very little escapes. Things can get in, but they have to be oving very fast, like eteors (rocks flying through space). Things can get out, but they have to ove very fast, like rockets. Whatever is on Earth right now, that s what we have to work with to ake our lives better. It s iportant, then, that we understand what is here on the planet with us. 3. DO: How well do you know your own hoe, the house you live in? Write down ten things you know about your house.

2 4. DO: How well do you know the planet that you live on? Write ten things you know about Earth. 5. DO: Write down five ways you know that Earth helps you stay alive.

3 2 LESSON THREE: THE SIZE OF THE PLANET YOU LIVE ON (The student will need access to the Internet.). UNDERSTAND THE WORDS: Moon a large object which circles a planet. Continent A very large ass of land. Island A ass of land not as large as a continent and surrounded by water. Population The nuber of peo (in this case) living soewhere. Desert A large area of Earth where there s very little rain. 2. READ ALOUD TO THE TEACHER: Ocean A very large body of water which separates the continents. Earth is saller than the sun. About,000,000 planet Earths would fit into the sun! Jupiter is the largest planet in this solar syste. You could fit over,300 of Earth into Jupiter. But Earth is larger than soe other planets. To give an idea, here s a drawing fro NASA showing how big each planet is copared to the other planets. In order left to right (and this is the order the planets are in oving away fro the sun) is tiny Mercury, Venus, Earth, red Mars, Jupiter, turn, Uranus, Neptune, and then a sall object we used to think of as a planet but now we think it s too sall, naed Pluto:

4 3 As you can see, Earth is bigger than any of the other inner planets, but saller than any of the gas giants. And Pluto well, it s not a planet anyore, I guess. Earth is also bigger than any things in space, such as our own oon. However, other big planets have oons alost the size of Earth. Earth is the third planet fro the sun. We are over 90,000,000 iles away fro the sun, which is just far enough for our planet to get enough heat to keep water fro freezing, but not so uch heat that water boils away. If we were farther away, Earth would be too cold for the kinds of life that have grown up here. If we were closer, it would be too war. So how big is Earth? Do you know what a ile is? You will find out in this lesson. If you drove around the equator of Earth, you d have to drive 25,000 iles. And you can t drive around the equator unless your car can go under or over water. Much of the surface of Earth is water, over 70%. The rest is land. You and all the peo you know live on about /3 of Earth, on its lands, either on a continent or an island. A continent is a huge body of land. Earth has seven continents. They are: North and South Aerica, shown at these links: (just look at one. If you see Oceania, that is also known as Australia. If you see Greenland, that s a very large island and not a continent. ) There are seven continents; Not Aerica, South Aerica, Europe, Asia, Africa, Australia and Antarctica. These are separated by one huge world ocean which we think of as several oceans.

5 4 How big are the seven continents? Here are their sizes in square kiloeters, a way of easuring area (how uch space a thing takes up). Here also is a list of how any peo lived on each continent as of BY SIZE # Asia - (44,579,000 sq k) #2 Africa - (30,065,000 sq k) #3 North Aerica - (24,256,000 sq k) #4 South Aerica - (7,89,000 sq k) #5 Antarctica - (3,209,000 sq k) #6 Europe - (9,938,000 sq k) #7 Australia/Oceania - (7,687,000 sq k) BY POPULATION 204 # Asia (4,35,000,000) #2 Africa (,36,000,000) #3 Europe - (74,000,000) #4 North Aerica - (353,000,000) #5 South Aerica (68,000,000) (includes Latin Aerica, the Caribbean) #6 Australia/Oceania - (39,000,000) #7 Antarctica - (0) (Interesting note since 2005, the population in each continent went up except in North Aerica, where it went down a little.) How big is a continent? Big. Asia is half again as large as the next largest continent, Africa. Australia is about /6th the size of Asia. But even Australia is siply enorous. Look at how any countries peo have squeezed onto each continent as of 205, except Antarctica which is so cold no one lives there year round: # Africa - (54) #2 Europe - (47) #3 Asia - (44) #4 North Aerica - (23) #5 Oceania - (4) #6 South Aerica - (2) #7 Antarctica - (0) Your country is on one of these continents. Each continent is ade of billions of tons of rock rising out of the ocean. Islands are also rock rising fro the ocean. Life has changed these dead rocks into land we can keep living on. Plants have broken the rocks up, and ade it so we can grow food that we and other anials live on. Except in a few places that are pretty dead such as a desert (a place where there is very little rain), or very high ountains (where there s very little air and it gets very cold), life can be found alost anywhere on land.

6 5 Life also fills ost areas of the ocean, which covers far ore of the world than the continents do. How large is Earth? It s large enough that if you were flying,000 iles per hour, you could circle it in just over one day. It s large enough to hold seven great continents and thousands of iles. It s large enough to hold and support trillions of living things. 3. DO: On A ap, globe or the Internet, find a ap of the continent you either live on or near (if you re on an island). Find your own city or where you live. Peo live all over the world. Find these large cities on a ap of the world and look at how close or far away they are fro you: Tokyo, Japan London, England Paris, France Berlin, Gerany Roe, Italy Bucuresti, Roania New York, New York (United States) Los Angeles, California (United States) Montreal, Quebec (Canada) Sydney, Australia Peking, China Moscow, Russia St. Petersburg, Russia Cairo, Egypt Istanbul, Turkey Seoul, South Korea Jakarta, Indonesia Johannesburg, South Africa Mubai (or Bobay), India Buenos Aires, Argentina Lia, Peru 4. DO: With a teacher or parent, walk one ile. (Your teacher ay need to do a little hoework to know what a ile is in your neighborhood.) When you finish, iagine doing that ten ties! That would be ten iles. Iagine doing it 00 ties! One hundred iles. Then iagine doing that one ile walk every day for the next 25,000 days. (That s alost 69 years, every day, one ile.) If you did that, you will have walked far enough to walk around the equator. So how big is the world, in your own words? Write your answer.

7 6 PART TWO LAND LESSON FOUR: A VIOLENT BIRTH. UNDERSTAND THE WORDS: Religions Systes of belief that any peo accept and live their lives by. Gravity A force (energy oving in a certain direction) that holds a planet and things on it together. Core The center of a planet. Lava Molten (elted) rock that reaches the surface, as through a volcano. 3. READ ALOUD TO THE TEACHER: Maga Molten rock that does not reach the surface. It s easy to answer this question: What is land ade of. You probably know the answer. Land is ade of all kinds of rocks, including rocks that have been elted, blasted, and even worn down until they becae sane. Not only is the land you see ade of rock, but there is land at the botto of the ocean, every inch of ocean. The entire surface of our world is rock. Where did all this rock coe fro? How does a world like Earth get started? There are any different ideas of how Earth got started. Soe of those ideas coe fro religions. A religion is a syste of beliefs. A syste of beliefs is a group of ideas that work together and that peo accept without any proof. There are any religions on Earth, and each one has its own idea of how the world got here. But on this course, you re studying science. There are other courses where you ay study the ideas religions have about the start of our world, but not this course. This is a science course, so let s look at how any scientists think Earth got here. Most scientists believe that Earth has been around in one for or another for over four billion years. They believe that the solar syste started out as a huge cloud of very hot aterial that slowly cooled. As it cooled, it collected into sall pieces like floating, hot piles of rock in space. These ran into each other by the any illions, and created larger piles that held together because they got big enough to have soe gravity. (Gravity is a force that holds things together. You are kept on Earth rather than floating away because of gravity.)

8 7 The collisions of all these large space ountains and rocks caused ore heat. The rocks elted again and flowed into the ore or less round shape planets take. As the planets got bigger and bigger, they sucked in ore and ore of the stuff floating around the until just about all that was left was the sun and eight large planets. If Jupiter had grown uch larger than it is, it ight have becoe another sun. Many solar systes have two suns. It is even thought that another planet ay have run into Earth, splitting off soe of our world. The stuff that exploded off Earth when the planets crashed into each other created a ring around Earth, like the rings around turn. The objects in the ring slowly ran into each other and, just like the planets were fored, stuck together and created our oon. Here s a photo fro NASA of the Earth and oon as seen fro the planet Mars: The gravity of our world is so strong it holds the oon at pretty uch the sae distance all the tie. So if scientists are right, Earth is ade of the reains of crashing, huge rocks in space, early in the life of our solar syste. Those rocks created so uch heat that they elted. Scientists believe that Earth was a huge ball of olten rock for a very long tie. But over any illions of years, all the things that could have crashed into each other crashed. The crashing pretty uch stopped and Earth was allowed to cool.

9 8 Our world is still violent. Deep under the surface, the world is very hot. Our planet has what is called a core. The core is what s at the center of our world, any thousands of iles below your feet. It is thousands of degrees hot there, so hot that all rock elts. (Don t worry unless you live near a volcano, where this hot rock, called aga reaches the surface and becoes lava. If it were possible for a person to fall to the center of the world (it s not), he or she would fall for several days before getting there. That s how far away it is.) The core of our world is a violent reinder of its birth. 3. DO: Draw what scientists believe happened to for Earth. It will take a nuber of drawings. They do not need to be art, just show the ideas. 4. DO: Draw how scientists believe our oon was created, and take as any drawing as you need. Again, don t worry about art, just show the ideas.

10 9 LESSON FIVE: ROCKS. DO: Find on a ap, globe or the Internet: The Grand Canyon (United States) The Colorado River 2. UNDERSTAND THE WORDS: Geology The study of the land of Earth, what it s ade of and how it cae to be. Geologist A scientist who studies geology. Igneous The kind of rock fored when olten (elted) rock cools and hardens. Sedientary The kind of rock fored fro pieces of other kinds of rock are slowly brought together by wind, running water, or other ways. Pressure The force pushing against an object. (EXAMPLE: If you take your hands and push against a wall, you are putting pressure on that wall. Force is energy oving in a direction. You are oving energy (through your body and hands) against that wall. Try this now and you ll understand pressure.) Metaorphic The kind of rock fored when other rocks are placed in a lot of heat or pressure or both. 2. READ ALOUD TO THE TEACHER: The study of Geology is the study of land. Geology is a study of the non-living parts of our planet, its rocks. It s the study of what land is ade of and how it cae to be. It s also a study of what the land will do today. A person who studies Geology is called a Geologist. Land is active. It oves. As you will study, whole continents are oving! Miles under your feet rivers of aga ay be running. Earth is alive with otion and change, even the parts of it that are not alive.

11 20 2 Since the world was at first olten rock, all of it started as lava on the surface of Earth that cooled, or aga under the surface that cooled, as in a cave or ountain. Then why don t all rocks look the sae? Because they don t. Rocks can be as different fro each other as you can iagine! Just think of the difference between a diaond and coal: The diaond is at the center of the first photo. They don t look uch like each other, do they? Yet they are both types of rock. In fact, diaonds are coal! They are coal placed under great heat and pressure for a very long tie. All rock started at igneous rock. But not all rock stayed that way. Soeties igneous rock was placed under great heat and pressure, if it cooled underground. This changed the rock. It can change coal into a diaond, the hardest natural surface on Earth. These changed rocks are called etaorphic rocks by geologists. What decided the sort of rock a rock becae was where and how it cooled. There is a third sort of rock. Over any thousands and illions of years, rocks wear down. They get beat up by rain and wind. If a rock is in running water, the river or strea will slowly wear the rock away, taking little pieces of it. These little pieces eet up with other little pieces fro other kinds of rocks. Over a long tie, they stick together as ore little pieces show up and clib on top. The pressure fro the new pieces on top squeeze the ones below into a new kind of rock, called sedientary. There are any kinds of igneous, etaorphic and sedientary rocks. These three big categories of rock are one of the first things you ust understand about geology. Igneous rocks can be black and dull, or black and shiny. They can have color in the. They can look as if any sall bubbles exploded through their surface, which is what happened to such rocks.