It is a lot harder to climb a mountain than to hike across a plain. You might need special shoes to help your feet grip the ground on a mountain or ropes to help pull you up in steep places. A plain is flat. A mountain rises up high above the ground.
The Highest Mountain on Each Continent Continent Mountain Location feet meters
Continent Mountain Location feet meters Asia Mount Everest China-Nepal 29,035 8,850 South America Aconcagua Argentina 22,834 6,960 North America Mount McKinley United States 20,320 6,194 Africa Kilimanjaro Tanzania 19,341 5,895 Europe Mount Elbrus Russia 18,510 5,642 Antarctica Vinson Massif Antarctica 16,066 4,897 Australia and the Pacific Islands Mount Wilhelm Papua New Guinea 14,793 4,509
HOW DO MOUNTAINS DIFFER FROM HILLS?
You would have a longer climb to the top of a mountain than to the top of a hill. Mountains are higher than hills. The tallest mountain in the world is Mount Everest between Nepal and Tibet. The top of Mount Everest is 29,035 feet (8,850 meters) above the level of the sea. That’s more than five miles high!
Most hills are rounded. A mountain comes to a peak at the top. A mountain looks a little like a pyramid. A mountain has a wide base, or bottom, and a narrow top.
Some mountains stand by themselves. Most mountains are in groups called ranges. Mount Everest is in a range called the Himalayas. The Rockies and the Appalachians are mountain ranges in North America. Low places between mountains in a range are called valleys.
WHERE DO MOUNTAINS COME FROM?
Geologists (scientists who study the Earth) think that some mountains come from movements in Earth’s crust. The crust is the rocky outside layer of Earth. Geologists think that Earth’s crust is made up of gigantic pieces called plates that move around very slowly.
Sometimes the moving plates crunch together. The edges of the crunching plates wrinkle up to make mountains. Plates crunching together and wrinkling up made the Himalayas and the Rocky Mountains.
Sometimes one side of a plate lifts up like a big block of rock. You can see these kinds of mountains in the southwestern United States.
Some mountains form when hot, melted rock oozes up from deep inside Earth. The melted rock is called magma. Mountains made from magma are volcanoes. Magma that comes out of the top of a volcano is called lava. Lava cools, turns solid, and builds up to make the hard rock that forms a mountain. Mount Rainier near Seattle, Washington, is a volcano.
Some mountains are carved out by erosion. Wind and water wear away soil and soft rock. The hard rock stays and becomes mountains. The Ozark Mountains in Arkansas and Missouri were made by erosion.
13 September 2009
All about Mountain
All about Ocean
When most people think about Earth, they think about land. You’ve probably spent your entire life on land. If you look at a globe, however, you can see that there is not as much land as water. Most of the Earth is covered by water, and most of that water is salty. Almost all of the salt water is connected into one huge ocean. The ocean covers almost two-thirds of the Earth. Ocean square miles square kilometers Pacific Ocean 63,980,000 165,700,000 Atlantic Ocean 31,810,000 82,400,000 Indian Ocean 28,360,000 73,440,000 Arctic Ocean 5,430,000 14,060,000
ONE OCEAN OR MANY?
There is only one world ocean. Big pieces of land called continents divide the world ocean into parts, but all of the parts are connected. The four major parts are called the Atlantic Ocean, the Pacific Ocean, the Indian Ocean, and the Arctic Ocean.
Parts of some oceans are called seas. The Caribbean Sea and the Mediterranean Sea are part of the Atlantic Ocean. The Coral Sea is part of the Pacific Ocean.
HOW DEEP IS THE OCEAN?
The ocean is not very deep at the beach. Water along seashores might not even cover your toes. You can wade out into the ocean. You can stand on the bottom near a beach.
Farther out, the ocean is very deep. The deepest parts are in the Pacific Ocean. A place called the Mariana Trench is almost 7 miles (11 kilometers) deep!
Some parts of the ocean floor are flat. Other parts have underwater mountains. The Mid-Atlantic Ridge is a mountain range under the Atlantic Ocean. Melted rock called magma oozes up from cracks along the Mid-Atlantic Ridge. The magma cools and makes new rock.
IS OCEAN WATER WARM OR COLD?
The ocean is freezing cold in some places and very warm in others. The Arctic Ocean near the North Pole and the ocean in the south around Antarctica are freezing cold. You can see icebergs floating in these oceans.
Ocean water near the equator is always warm. The equator is an imaginary line around the middle of Earth. You can swim in the ocean near the equator all year long.
CURRENTS IN THE OCEAN
The ocean has “rivers” of cold or warm water running through it. These “rivers” are called currents. One of the best-known currents is the Gulf Stream. The Gulf Stream carries warm ocean water from the equator up to the north part of the Atlantic Ocean.
Warm and cold ocean water is always moving around the world. In some places cold water comes up from deep in the ocean. Warm water sinks down. Wind blows ocean water at the surface. Waves also move ocean water. Changes in ocean currents can make weather changes on land. Sometimes the changes cause mild winters in some places and lots of rainfall in other places.
WHAT LIVES IN THE OCEAN?
The ocean is full of living creatures. The tiniest ocean creatures are plankton. Plankton drift on the surface. The biggest ocean animal is the blue whale. The blue whale can be 80 feet (24 meters) long. It is the biggest animal on Earth.
Many kinds of fish and shellfish live in the ocean. Your tuna sandwich comes from the tuna, a fish that swims in the ocean. Crabs, lobsters, and shrimp crawl around on the ocean floor. Squid and octopus dart about with their long arms and tentacles.
Different creatures live at different ocean depths. Very strange creatures live deep in the ocean where there is no sunlight. Some deep-ocean fish glow in the dark. Some of them are blind.
PROTECTING THE OCEAN
Oceanographers are scientists who study the ocean. They worry about ocean pollution. Thousands of ships carry oil and other goods across the ocean. Oil spills from ships can pollute the ocean. People build factories close to the ocean shore. Chemicals from factories can pollute the oceans. Chemical bug killers from farms can also drain into the ocean.
People get many things from the ocean. Fish and other food come from the ocean. It is important to keep ocean water clean.
09 September 2009
space travel
You’re strapped into a seat. You hear a loud roar. Rocket engines fire and lift you into the sky. The rocket goes faster and faster, pushing you harder and harder against your seat. Suddenly, everything gets quiet. The engines stop. You take off your seat belt and start to float around. You are almost weightless. This is what space travel feels like.
GETTING INTO SPACE
Since ancient times, people have dreamed of leaving Earth and exploring other worlds. But gravity holds everything on the ground. Gravity is a pulling force between two objects. Earth is a very large object, and its gravity is strong. Even airplanes that fly thousands of feet above Earth can’t leave our atmosphere and go into space. Scientists and engineers had to make a force much greater than gravity to travel to outer space.
Finally, the dream came true. Engineers built rockets powerful enough to lift a rocket into space. In 1957, scientists from the Union of Soviet Socialist Republics (USSR) sent the first artificial satellite, Sputnik 1, into space. The United States soon sent an artificial satellite, Explorer 1, into space as well. The Space Age had begun.
The first spacecraft just orbited (went around) Earth. There were no humans on these spacecraft. Then scientists sent robot spacecraft to the Moon. The spaceships carried cameras that took pictures of the Moon’s surface. Some robot spacecraft even landed on the Moon.
The first person went into space in 1961. Soviet cosmonauts and American astronauts made several trips into orbit around Earth. The next goal was to send people to the Moon.
HEADING FOR THE MOON
After the Space Age began, engineers worked hard to figure out how to send people to the Moon. They made controls for steering spacecraft. They made spacesuits to allow astronauts to breathe and keep them safe from heat, cold, and harmful rays.
Engineers made special rocket ships for taking astronauts to the Moon. They named this series of spacecraft Apollo. An Apollo spacecraft held three astronauts. It also carried a smaller landing ship that looked sort of like a spider.
LANDING ON THE MOON
In July 1969, three astronauts in Apollo 11 headed for the Moon. On July 20, they made history. Astronauts Neil Armstrong and Buzz Aldrin climbed into the landing module, which was named Eagle. They went down to the Moon. The spiderlike legs of the lander dug into the Moon’s surface. Armstrong radioed back to Earth, “The Eagle has landed.” When he stepped on the Moon, Armstrong said, “That’s one small step for man, one giant leap for mankind.”
Astronauts in other Apollo spacecraft landed on the Moon five more times. Astronauts in spacesuits walked around on the Moon. They rode around in a kind of car called a lunar rover. All the astronauts brought back moon rocks and soil for scientists to study.
VISITING OTHER PLANETS?
Astronauts haven’t yet visited another planet. Robot spacecraft, also known as probes, have journeyed to all the planets except Pluto. These space probes carried cameras and took pictures of the planets. They studied gases around the planets. They can send these pictures and other information back to Earth by using special radio equipment.
Some of the space probes fly quickly past other planets. Voyagers 1 and 2 took off in 1977 to fly by Jupiter, Saturn, Uranus, and Neptune. After zooming by these planets, the Voyager probes headed out of the solar system. They continued to explore the space between the stars.
Some probes go into orbit around a planet. Some also drop landers on these planets. Several Soviet probes dropped landers on Venus. An American probe dropped a lander on Jupiter. More probes and landers continue to be sent, designed to explore other planets.
EXPLORING MARS
Of all the planets in the solar system, Mars is the most similar to Earth. Beginning in the 1960s, many robot spacecraft visited Mars. The Viking mission in 1975 was the first probe to safely land on Mars. A camera sent pictures of the surface to Earth. A robot arm scooped up soil.
The Mars Pathfinder spacecraft landed on Mars in 1997. It had a robot wagon called the Sojourner rover. The rover moved around on Mars, taking pictures and studying rocks. Other probes, landers, and rovers went on to study Mars.
Some people dream of astronauts someday landing on Mars. Other people say it would be best to send more robots. If astronauts do go to other planets, Mars would be the first one they visit.
THE SPACE SHUTTLE
In the 1970s, the United States developed a new kind of spacecraft called a shuttle. The shuttle blasts into space on big rockets. Unlike previous spacecraft, which used lander ships and could only be used once, the shuttle can land on Earth like an airplane and be used again. The first shuttle flew into space in 1981.
The shuttle has a big area called a cargo bay to hold large equipment. Astronauts on space shuttles launch satellites from the cargo bay. Some satellites study Earth from space, while others relay phone calls and other communications. Astronauts can also launch space telescopes from the shuttle.
LIVING IN SPACE
Space travel is hard on people’s bodies. Spending long amounts of time in space makes bones and muscles weak. It is hard to eat in space. It is hard to sleep and take showers.
Scientists use space stations to study how people can live and work in space. Space stations orbit around Earth. The Soviets sent up several space stations. The first, Salyut 1, was launched in 1971. The first U.S. space station, Skylab, was launched in 1973.
The most famous Soviet space station was Mir, which orbited Earth from 1986 to 2001. Astronauts from many different countries visited Mir. Many of them performed experiments on the space station. They learned many things about living and working in space.
In the late 1990s many nations worked together to build an International Space Station. The space shuttle carried parts for the station into space. Astronauts put the pieces together. The International Space Station was scheduled to be completed by 2006. The goal is to have people living and working in the space station all the time. Someday, maybe everyone who wants to will be able to travel into space.
Knowledge about Maps
Have you ever drawn a picture of your street, town, or neighborhood, showing landmarks like trees, homes, and stores? If you have then you’re already a mapmaker. Or, to use a fancier word, you’re a cartographer!
WHAT ARE MAPS AND GLOBES FOR?
Maps show the locations of places on a sheet of paper. Globes are a type of map. But instead of being flat, globes are ball-shaped. This makes them more like Earth, the Moon, or other planets they represent.
Maps help show where one location is when compared with another. They can help you get from place to place. They can also provide other types of information. How high is a mountain range? How deep does a certain spot in the ocean go? Are there mineral deposits in a particular region? In what sections of the world do the most people live? These are all questions that the right kind of map can answer.
TYPES OF MAPS
The most common maps are called general maps. They usually show a mix of geographic and political features. Geographic features are things in nature, such as mountains, lakes, and rivers. Political features, in comparison, are decided on by people. They include lines showing where one country or state ends and other ones begin.
Thematic maps are another type of map. Thematic maps do not give as many types of data as general maps. Instead, they give more details about a specific topic. A thematic map, for example, may provide specifics about an area’s climate or natural resources. It could show you what languages the people living there speak, or even how much coffee they drink!
Charts are another category of maps. These special maps help sea captains and airplane pilots navigate. Why are their maps different from others? Captains out on the ocean and pilots up in the air rely on landmarks and symbols not usually needed by others. Ships, for example, need to know where the shallow places in the ocean are and which way the water currents move.
WHAT A RELIEF!
If you run your finger along most maps, you’ll find a smooth surface. However, if you have a map or globe that’s done in relief you might feel bumps representing high places like mountains, and dips representing low places like valleys.
Some relief maps use clay or plastic molding to make the bumps and dips. Others rely on colors or shapes to represent areas that are higher up or lower down. A special kind of map called a stereogram requires 3-D glasses. These glasses trick your eyes into seeing a flat page’s surface as though it were shown in three dimensions.
HOW TO READ A MAP
Almost all maps contain certain aids to help you read them. North is toward the top of most maps. But to make sure, look for an arrow on the map showing one or more cardinal directions (north, south, east, and west).
A key or legend is also found on just about all maps. A legend is a list of the symbols used on the map, along with each symbol’s meaning. A legend helps you figure out what the dots, circles, colors, and squiggly lines on a map stand for. A dot might, for example, represent a city, museum, group of people, or something else entirely.
A scale allows you to determine the size of the area shown on a particular map. Does a centimeter or an inch stand for a mile, a kilometer, or a million miles? The scale helps you compare the short distances on the map with real-life distances.
Lines of latitude and longitude also help you to read a map. Lines of latitude are imaginary lines that run around Earth from east to west. Lines of longitude are imaginary lines that circle Earth from north to south. Lines of longitude pass through the North Pole and the South Pole. Together lines of latitude and longitude create a grid on maps that allows you to describe precisely any spot on Earth.
