Background Information: Mercury, Venus, Mars, Jupiter and Saturn are the five planets visible to the human eye. Although the planets look like stars, they do not move like stars. Ancient stargazers noticed that five stars changed position with respect to the other stars and each other. The Greeks called these stars planets, which means "wanderers". For hundreds of years researchers tried to explain the motion of these "wandering stars". Students can learn more about early astronomers and their work by doing library research on Aristarchus of Samos, Ptolemy, Copernicus, Tycho Brahe and Johannes Kepler.
Astronomers began using the telescope to study the sky in the 1600's. For over 300 years the telescope was the most important tool for astronomers. Galileo made some of the earliest discoveries with the telescope. However, Galileo did not invent the telescope; he was not even the first to use a telescope to study the sky. Galileo is known for his careful observations and the detailed records in his journal. Galileo sketched the features of the moon and even measured some of the mountains. He discovered the four large satellites of Jupiter. Galileo observed that Venus went through phases like the phases of the moon. Sunspots were discovered independently by Galileo, Fabricius and Scheiner. Around 1655 Christiaan Huygens discovered the rings of Saturn and Saturn's largest moon. In 1781 William Herschel discovered Uranus. Later he discovered two new satellites of Saturn and two satellites of Uranus. Leverrier and Adams calculated the approximate location of Neptune. Using these calculations, Galle and d'Arrest where able to confirm Neptune's existence in 1846. In 1930 Clyde Tombaugh confirmed the existence of Pluto. In 1950 Jan Oort described the Oort Cloud, the source of comets. Halley predicted the return one of the most famous comets, now called Comet Halley. Shoemaker and Levy discovered the Comet Shoemaker-Levy 9, which hit Jupiter in 1994. To learn more about telescope research, students can do research about any of the people mentioned above.
In 1962 the first spacecraft (Mariner 2 to Venus) left Earth to explore the planets. Since then dozens of spacecraft have sent back important information about the planets and spectacular images. For this assignment students will study some of the best images of the Solar System. The collection contains images from all the planets, including Earth. The images depict the variety of features found on the planets and their satellites. Some of the features found
in the images are volcanoes, lava flows, mountains, canyons, valleys, rocks, soil, dunes, and craters. Other images include clouds, atmospheres, belts, zones, and atmospheric storms, such as Jupiter's Great Red Spot. The images show the rings and moons of planets. See The Researcher's Description for more details about the images. By studying these features, researchers are able to learn about the origin of the Solar System and how the planets have changed over time.
The Researcher's Descriptions contain detailed information for each image. Students will be able to answer question 1 from the title. In question 2 students should indicate visual characteristics that will help them identify the planets and their special features in the future. For example students may note the smooth blue color of Neptune or the craters on Mercury.
Suggestions: Most middle school students recognize the names of the planets and have a general sense of their relative order from the Sun. To confirm this, ask the students to diagram the Solar System or list the planets in order from the Sun before they begin. Use the study questions to assess their knowledge about exploration of the Solar System, and use the discussion to prepare them to study images from spacecraft.
Before going to the computers, assign two to three students to work together at each computer. Observations can be enhanced by student discussions, but students should make independent entries in their journals. Let students know that Galileo is famous because he made careful observations and kept a detailed journal.
Remind students to leave room for Part II notes after the entry for each image. If students are not familiar with peer review, you may want to take some time before they go to the computers to discuss how to do it.
If there are not enough computers for the class, students could work on library research suggested in the background information. If time is limited, students can select fewer than ten images. If time allows, you may want students to sketch the image in their journals.