Wikijunior:Solar System/Introduction
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| The Solar System |
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Introduction |
Contents |
[edit] Introduction
Wikijunior books welcomes you to the children's book "Solar System". Outer space is perhaps the final frontier for man. Even though the rest of the solar system objects may seem like tiny dots from Earth, our celestial neighbors are still important to learn about. The importance of this task has led many experts here at Wiki to donate their time and talents to bring this volume together.
Wikibooks is a project of the Wikimedia Foundation, aimed at providing free, easily available, quality reading for adults and children to promote the global spread of knowledge. Traditional publishing houses make the bulk of their income from re-issues of classic books, new books by authors with long track records, or celebrities who are famous in their own right. The chances of a truly good new work being published solely on the basis of merit skyrocket when the traditional business model is overturned and the wellspring of new talent out there is tapped using the 'net.
With this project we have reached a crossroads between the books of yesterday and the encyclopedia of everything for tomorrow. Simply by reading this book and telling your friends about it, you have advanced the cause of free access to information and of democratizing the field of publishing. Thank you, and once again, welcome.
[edit] What is in the night sky?
What is up there in the sky? During the day, you can often see puffy clouds floating high in the air, and a huge ball of gas called the Sun. But when you look up on a cloudless night, you can see other things up there: the Moon and many, many stars. What are they? How many are there? How large are they? Can I touch them? These are only some of the questions human beings have pondered in the past and continue to ponder.
People have invented telescopes to see these planets and stars better. Stars are very hot balls of gas. Planets look like stars to the naked eye, but if you look at them every night for a month or so, you will notice how they move across the sky. That is because they are moving in their orbit around the sun, just like Earth! There are eight major planets in our solar system: Mercury, Venus, Earth, and Mars are the inner planets; Jupiter, Saturn, Uranus, and Neptune are the outer planets.
[edit] How is the Solar System measured?
When we look at things in the Solar System, we try to measure what we see. This allows us to compare the many objects and to know how and where they will move. To make it easy to share what we know with each other, a common method is used. Most of the world now measures the Solar System using the metric system. This system is a set of values that can be used to measure everything.
In this book, all of the measured values are in the metric system. This was first used in Europe during the eighteenth century. It was meant to replace all of the older systems of measuring things, such as the English system that used units such as feet, inches, pounds, and degrees Fahrenheit. The use of the metric system has made it much easier for people to agree on common sizes for things that are sold and to share information.
The types of values that are shown in this book are length, mass, temperature, and time. Length is used for values such as the size of a planet or the distance of a moon from a planet. Mass can be thought of as the weight of something if it was on the surface of the Earth. So if you weigh 30 kilograms on Earth, your mass is 30 kilograms. If you went somewhere where there was no gravity you would weigh nothing at all, but you would still have a mass of 30 kg. So the weight measures the pull of gravity on something with a given mass.
In the metric system, the length of something is measured in metres. A typical adult is about 1.7 metres high. One metre, in the old English system, is a little longer than 3 feet, 3 inches. The metre is sometimes shortened to an m. 'Metre' is spelled 'meter' in the United States.
For longer distances, the kilometre is used ('kilometre' is spelled 'kilometer' in the United States). A kilometre is a thousand metres. In the old English system, a kilometre is equal to about five-eighths of a mile. It is often shortened to km.
Mass is usually measured in grams. A thousand grams is called a kilogram. The kilogram is often shortened to kg. In the old English system, a kilogram is equal to about 2.2 pounds.
Finally, the temperature of something is measured in degrees Celsius. A degree is sometimes written as a little circle to the right of a temperature value. So 25° means twenty five degrees. The Celsius scale is based upon the temperatures at which water freezes and boils. At 0° Celsius, water at the surface of the Earth will freeze. When the temperature reaches 100° Celsius, water will begin to boil. Celsius is often shortened to C.
[edit] Introduction for Parents, Guardians, and Educators
The Solar System is a Wikijunior book written by a group of volunteers and made freely available to Internet users, printers, and distributors under the terms of its license. It is the result of cooperation between The Beck Foundation, The Wikimedia Foundation, and volunteer writers and editors.
The volunteer writers and contributors thank you for obtaining this book. By making it available to a young person you complete the goal of the Wikijunior project to encourage reading and literacy among young people.
The original text and graphics are available at http://www.wikibooks.org and printed versions may be available from many different entities under license.
