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e-Journal

The Positions of Earth and the Sun (pp. 580–581)


Step 1. Questions

Long ago, people believed that the Sun, the Moon, and the planets revolved, or moved, around Earth. Astronomers have studied the skies to discover the truth about the solar system. These scientists have learned that Earth and the other planets revolve around the Sun.

Write a report about how people's views of the solar system have changed over time. To do so, you will need to research the astronomers who contributed to our understanding of the solar system. Here are some questions to guide your research:
  • Why did the people of long ago believe that Earth was the center of the solar system?
  • How did Aristotle and Ptolemy view the solar system?
  • Who was Copernicus, and what did he learn about the solar system?
  • How did Galileo support Copernicus's theory about the solar system?
  • What discoveries are scientists making about the universe today?
Are you ready? Begin by visiting the Web sites in Step 2. Look for answers to the questions above, and write down what you learn in the note-taking boxes.

With teacher supervision, you may use search engines to research other Web sites. You also can research the work of early astronomers at the library. When you are ready, follow Steps 3 and 4 to write your report.


Step 2. Research

Research answers to the questions you were asked in Step 1. Visit these Web sites. Take notes about them on this page, too!


Toolbox Tip: Click here to learn what plug-ins are and how to install them on a computer.


Early Astronomers: Ptolemy, Aristotle, Copernicus, and Galileo
Read about astronomers of long ago. How did each astronomer contribute to knowledge of the solar system? The Central Rappahannock Regional Library in Virginia sponsors this Web page.
Take Notes:



Stargazers
This Web site contains a great deal of information about the astronomers who have studied the movement of the solar system. Click the picture of Copernicus to begin. This Web site is provided by a partnership between Discovery Education and the American Museum of Natural History.
Take Notes:



The Heliocentric and Geocentric Models
This Web page is from the University of Toronto in Canada. Long ago, people believed in the geocentric model, or the theory that Earth is the center of the solar system. Today, we refer to the heliocentric model when we describe the Sun as the center of the solar system. Watch the animations to see how the models differ. Earth is the blue circle, the Sun is the yellow circle, and Mars is the red circle.
Take Notes:



Additional Sites

Cosmic Questions Exhibit
This Web page has a link to the "Fly Through the Universe" tour. Go on the tour to fly toward the planets and then beyond our solar system. To start the tour, look for the words "click here" within the text about halfway down the page. Click CLICK HERE to open the video. As you go through the tour, think about the job of an astronomer and what these scientists have discovered about the universe.
Take Notes:



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