Astronomy

Astronomy

Astronomy

Level: 8th Grade
Time Frame: 1 Quarter
Description: Through studying the history of astronomy, students will see the interaction of revolutionary new ideas in science and then repercussions in society. Characteristics of meteors, comets, and the planets of our solar system are compared and contrasted. Stars and galaxies are examined as well as theories of the formation of the universe.

Overview
Activity List
Learning Objectives
Standards
Resources

Unit Overview
This unit starts with observational activities intended to get students outside and making direct observations of objects in the sky—just as early astronomers did. Observing the sky unaided by telescopes, etc., helps students develop a sense of how early ideas about astronomy were developed when people had to rely only on what they could see with the naked eye. Although it can be difficult for students to remember to make observations outside of school hours, this should be encouraged.

In the text and in the standards, there is a great deal of emphasis on the motions, changes, and relative positions of objects in space. Some standard content--such as moon phases and the detailed characteristics of planets in the Solar System—is missing or covered minimally. There is a rationale for this. By middle school, students should be aware that the moon doesn’t really change shape and that it can be seen because it reflects light from the sun. Spending a lot of time learning exactly why it reflects light differently at different times is not considered as important as simply recognizing that it is due to the relative movement and position of the earth, sun, and moon.

With regard to planets, the emphasis in the text is on Mars because it is the one planet that could potentially be colonized by humans. The other planets are out there, but as far as we know they are not conducive to supporting life of any sort, and are therefore of lesser interest. It is difficult for us to even gain much knowledge about these planets. On the other hand, objects such as meteors and comets are emphasized in the text/standards because they provide information about the formation of the solar system, and because meteorites provide our only means of directly investigating matter that comes from other parts of the solar system.

The text includes a fairly detailed activity related to understanding the seasons, attempting to clear up some typical misconceptions. However, as noted in the National Science Education Standards, research shows that many middle school age students are not likely to truly understand the explanation, even with the use of models. One should therefore have realistic expectations about the outcome of the activity.

Space exploration per se is not included in the National Standards or Benchmarks related to “learning about the universe,” and the primary text includes this topic by relating it to learning about the planets. However, space exploration is included in the Illinois performance descriptors for this topic; this topic allows for coverage of some of the physical science and technology standards; and space exploration is inherently interesting to many students. Some of the extension activities will allow students to further explore this topic, if desired.

The Big-Bang Theory of the origins of the Universe is introduced at the end of the unit, but this is considered a high school topic, so it is not explored in any great detail.

From the National Science Education Standards:
“A major goal of science in the middle grades is for students to develop an understanding of earth and the solar system as a set of closely coupled systems. The understanding that students gain from their observations in grades K-4 provides the motivation and the basis from which they can begin to construct a model that explains the visual and physical relationships among earth, sun, moon, and the solar system. Direct observation and satellite data allow students to conclude that earth is a moving, spherical planet, having unique features that distinguish it from other planets in the solar system. From activities with trajectories and orbits and using the earth-sun-moon system as an example, students can develop the understanding that gravity is a ubiquitous force that holds all parts of the solar system together. Energy from the sun transferred by light and other radiation is the primary energy source for processes on earth's surface and in its hydrosphere, atmosphere, and biosphere.

By grades 5-8, students have a clear notion about gravity, the shape of the earth, and the relative positions of the earth, sun, and moon. Nevertheless, more than half of the students will not be able to use these models to explain the phases of the moon, and correct explanations for the seasons will be even more difficult to achieve.”

From the Benchmarks for Science Literacy (grades 6-8):
“Students should add more detail to their picture of the universe, pay increasing attention to matters of scale, and back up their understanding with activities using a variety of astronomical tools. Student access to star finders, telescopes, computer simulations of planetary orbits, or a planetarium can be useful at this level. Figuring out and constructing models of size and distance—for example, of the planets within the solar system—is probably the most effective activity. Models with three dimensions are preferable to pictures and diagrams. Everyone should experience trying to fashion a physical model of the solar system in which the same scale is used for the sizes of the objects and the distances between them (as distinct from most illustrations, in which distances are underrepresented by a factor of 10 or more).

Some experiences with how apparent positions of objects differ from different points of observation will make plausible the estimation of distances to the moon and sun. Finding distances by triangulation and scale drawings will help students to understand how the distances to the moon and sun were estimated and why the stars must be very much farther away. (The dependence of apparent size on distance can be used to pose the historically important puzzle that star patterns do not appear any larger from one season to the next, even though the earth swings a hundred million miles closer to them.)

Using light years to express astronomical distances is not as straightforward as it seems. (Many adults think of light years as a measure of time.) Beginning with analogs such as "automobile hours" may help.”

Activity List

Lesson 1(19:1): What is Astronomy? (Text pp 422-426)
Lesson 2 (19:2): An Ancient Science (Text pp 427-435)
*Optional Extensions/Resources
Lesson 3 (20:1): A Scientific Revolution (Text pp 438-444)
*Optional Extensions/Resources
Lesson 4 (20:2): Motions and their Effects (Seasons) (Text pp 445-451)
Lesson 5 (21:1): Visitors from Space (Meteors, comets) (Text pp 455-459)
*Optional Extensions/Resources
Lesson 6 (21:2): The Space Probes (Text pp. 460-464)
*Optional Extensions/Resources
Lesson 7 (21:3): Colonizing the Solar System (Text pp. 465-469)
*Optional Extensions/Resources
Lesson 8 (22:1): Messages from the Stars (Text pp. 472-479)
*Optional Extensions/Resources
Lesson 9 (22:2): Earth’s Place in the Universe (Text pp. 480-486)
Lesson 10 (22:3): A Likely Beginning (Text pp. 487-489)

Learning Objectives

Suggest a definition for astronomy.
Identify some of the objects observed and studied by astronomers.
Evaluate models of the universe as put forth by Aristotle, Aristarchus, and Ptolemy.
Explain the difference between heliocentric and geocentric models of the solar system.
Explain the motions of celestial bodies by using the Copernican model of the solar system.
Explain the apparent retrograde motion of Mars.
Explain what is meant by the plane of the ecliptic.
Draw a scale model of the distances of the planets from the Sun.
Explain why the amount of daylight changes throughout the year.
Describe how the tilt of Earth on its axis creates the seasons.
Identify the position of Earth during the summer and winter solstices and the vernal and autumnal equinoxes.
Illustrate how a planet orbits the Sun by drawing an ellipse.
Identify the difference between a meteor, a meteorite, and a comet
Explain why many meteorite-impact craters are visible on the Moon but not on Earth.
Describe the composition of meteors and comets.
Explain the origin of comets.
Describe the relationship between comets and meteor showers.
Describe in general terms the distances that separate the planets.
Identify some of the principal features that distinguish one planet from another.
Explain how technology has been used to gather data about the planets.
Compare and contrast Mars and Earth.
Discuss the possibility of establishing a colony on Mars.
Describe the size of the stars, using comparisons to Earth and the Sun.
Explain the relationship between the color of a star and its temperature.
Describe the life span of stars.
Describe Earth's place in the solar system, the Milky Way galaxy, and the universe.
Explain what astronomical units and light-years are and how they are used.
Describe the bi-bang theory as one way of explaining how the universe began.
Identify cosmic microwaves and the expansion of the universe as two observable consequences of the big bang.

Standards

Illinois Learning Standards (Middle School) As a result of their schooling students will be able to:

F. Know and apply concepts that explain the composition and structure of the universe and Earth's place in it.

12.F.3a Simulate, analyze and explain the effects of gravitational force in the solar system (e.g., orbital shape and speed, tides, spherical shape of the planets and moons).

12.F.3b Describe the organization and physical characteristics of the solar system (e.g., sun, planets, satellites, asteroids, comets).

Illinois Science Assessment Framework
Standard 12F - Astronomy (Grade 7)

12.7.91 Understanding that objects in the solar system is for the most part in regular and predictable motion. Know that those motions explain such phenomena as the day, the year, the phases of the moon, and eclipses.

12.7.92 Understand that gravity is the force that keeps planets in orbit around the sun and governs the rest of the motion in the solar system. Know that changes in gravitational forces explain the phenomenon of the tides. Know that what an object weighs on Earth is different than what it weighs on the Moon or other planets in our solar system. This is due to gravity.

12.7.93 Identify the differences among the planets in our solar system: the four closest planets to the Sun are called the inner planets. The inner planets are small and have rocky surfaces. The five farthest planets from the Sun are called the outer planets. All outer planets except Pluto are much larger than Earth, are made of gases, and have no solid surfaces.

12.7.94 Understand that rock samples taken by astronauts walking on the Moon show that the Earth and Moon have a common history.

12.7.95 Understand that because it takes the Moon the same amount of time to rotate on its axes as it does to revolve around the Earth, the same side of the Moon always faces the Earth.

12.7.96 Understand that valleys on the surface of a planet or moon might be evidence that water is or once was there.

12.7.97 Understand that the speed of a planet’s rotation is one cause of the daily variations in temperature on its surface.

12.7.98 Understand that the cause of the Earth’s seasons and the change in the amount of daylight throughout the year is the tilt of its axis of rotation with respect to the plane of it’s orbit. Given a diagram of the Earth depicting (1) its relative position to the Sun and (2) the orientation of its axis of rotation and (3) some circle of latitude, identify the following: (a) the season of the year (if the circle of latitude is other than the equator), and (b) whether there is more daylight or more dark hours at that time of year. Understand why the seasons and daylight hours in opposite hemispheres are opposite to each other.

12.7.99 Understand that the sun is an average star. Know that a solar system consists of a sun and planets and other objects that revolve around it. Know that the planets closest to the sun are hotter than the planets farther away form the sun. Understand that the color of a star depend on it’s temperature.

12.7.100 Identify the relative positions of the Earth, Moon, and Sun when the moon appears full, new, half, and when a lunar or solar eclipse occurs. Given a diagram of the Sun and the Earth in some definite position with it’s axis of rotation drawn (and with the poles labeled), identify the earth in the positions of summer solstice, winter solstice, spring equinox, and fall equinox (for the northern hemisphere).

12.7.101 Define light year, how many kilometers it is, and know that galactic distances may be measured in millions and billions of light years.

National Science Education Standards: Earth and Space Science As a result of their activities in grades 5-8, all students should develop an understanding of Earth in the solar system

The Earth is the third planet from the Sun in a system that includes the Moon, the Sun, eight other planets and their moons, and smaller objects, such as asteroids and comets. The sun, an average star, is the central and largest body in the solar system.
Most objects in the solar system are in regular and predictable motion. Those motions explain such phenomena as the day, the year, phases of the moon, and eclipses.
Gravity is the force that keeps planets in orbit around the sun and governs the rest of the motion in the solar system. Gravity alone holds us to the earth's surface and explains the phenomena of the tides.
The Sun is the major source of energy for phenomena on the Earth's surface, such as growth of plants, winds, ocean currents, and the water cycle. Seasons result from variations in the amount of the sun's energy hitting the surface, due to the tilt of the earth's rotation on its axis and the length of the day.

Benchmarks for Science Literacy By the end of 8^th grade, students should know that

The sun is a medium-sized star located near the edge of a disk-shaped galaxy of stars, part of which can be seen as a glowing band of light that spans the sky on a very clear night. The universe contains many billions of galaxies, and each galaxy contains many billions of stars. To the naked eye, even the closest of these galaxies is no more than a dim, fuzzy spot.
The Sun is many thousands of times closer to the Earth than any other star. Light from the Sun takes a few minutes to reach the Earth, but light from the next nearest star takes a few years to arrive. The trip to that star would take the fastest rocket thousands of years. Some distant galaxies are so far away that their light takes several billion years to reach the earth. People on earth, therefore, see them as they were that long ago in the past.
Nine planets of very different size, composition, and surface features move around the sun in nearly circular orbits. Some planets have a great variety of moons and even flat rings of rock and ice particles orbiting around them. Some of these planets and moons show evidence of geologic activity. The earth is orbited by one moon, many artificial satellites, and debris.
Large numbers of chunks of rock orbit the sun. Some of those that the earth meets in its yearly orbit around the sun glow and disintegrate from friction as they plunge through the atmosphere—and sometimes impact the ground. Other chunks of rocks mixed with ice have long, off-center orbits that carry them close to the sun, where the sun's radiation (of light and particles) boils off frozen material from their surfaces and pushes it into a long, illuminated tail.

Resources

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