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This is the  |
| 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 Wikijunior 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 internet.
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 others 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] Studying the Solar System
Scientists are still exploring the universe. Whether things are very tiny, like the cells of plants and animals, or very big like a solar system or a galaxy, there is still a lot scientists don’t know.
Scientists who study space are called Astronomers or Astrophysicists. They explore the solar system in two different ways. Astronomers do it by observing celestial bodies through telescopes, while astrophysicists (a specialized class of astronomers) try to explain the observed phenomena using physical laws and theorize about what is still unseen or unknown.
Telescopes were invented in the early 1600s in Europe and allowed curious scientists like Galileo Galilei to look at very distant things in close-up and see details of the solar system and the universe that nobody had ever seen before. Using his telescope, Galileo was the first person to see the rings around Saturn, and draw a very detailed picture of the moon. He also saw the four largest moons of Jupiter and spots on the Sun. Telescopes on Earth and in space are still used to explore the Solar System. There are several types of telescope; the most common ones are optical telescopes (such as Galileo's), and radio telescopes, that pick up radio waves from outer space.
Until the 1950s, humans were limited to exploring the Solar System from the ground. However, in 1957 the Soviet Union (now Russia) launched the very first satellite, Sputnik 1. Since then, humans have been launching vehicles into space to explore the Solar System—some that are manned (with people) and some unmanned (without people).
Now, the Solar System is full of human-made probes, exploring the planets and moons of the solar system. The probes send back information to Earth that scientists study to figure out what it means. Every year, scientists are learning more about the Solar System. Sometimes they learn things about other worlds that remind us of Earth. Other times, the things they learn are very strange. Everything they learn helps us to understand more about Earth, Earth's history and Earth's neighborhood.
[edit] How is the Solar System measured?
It’s important that scientists use measurement to tell how big, how hot or cold, or how far away something is. In science, people use the metric system, which is named after the meter. Below is a description of all the types of measurement used in this book.
[edit] Distance or Length/Width
To measure how far away something is, or how long or wide it is, scientists use kilometers or meters. There are 1000 meters in a kilometer. An average adult is about 1.7 meters tall. There are just over 3 feet in a meter. Kilometers is often shortened to km. Meters is often shortened to m.
Since distances outside of the Earth get so vast, scientists have also invented new units of measurement to make it easier to measure large distances in space. They invented the Astronomical unit (AU) which is equivalent to 149 597 871 kilometers. One Astronomical Unit is the approximate distance between the Earth and the Sun.
[edit] Mass
In order to measure how big something is, scientists measure the mass of an object in kilograms or grams. There are 1000 grams in a kilogram. Scientists do not use weight, because weight is a measurement that means how hard gravity is pulling on an object. An object’s mass is the same wherever you are in the solar system because it measures how much stuff, or matter, a thing is made up of. Your weight will change because the amount of gravity there is varies from place to place.
On Earth, mass and weight are the same. If you weigh 30kg (short for kilograms) on Earth, your mass is 30kg. If you are floating around in space, your weight if you try to stand on a set of scales will be 0kg, but your mass is still 30kg. You are still made up of the same amount of matter.
[edit] Temperature
Temperature is a measure of how hot or cold something is. Scientists use degrees Celsius to measure temperature. They write degrees as a little ‘o’ and Celsius gets shortened to 'C'. 25 degrees Celsius would be written 25°C. In degrees Celsius, 0°C is the temperature at which water freezes. Water boils at 100°C. 25°C might be the temperature on a warm sunny day. Temperatures below freezing are written as negative numbers. -5°C is a cold day. -25° is a very cold day!
[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.
