Our understanding of the universe and our place in it has changed over time. New information makes us rethink what we know and change how we classify objects in order to better understand them. In this chapter we learned how the way we classify objects as planets has changed. Questions 1. Can you think of any other example of how our understanding of Earth and space has changed over time?
2. What information led to this change? Chapter Summary
1. The universe is all of space and everything in it. 2. A star is a large ball of gas that gives off light and heat. 3. A solar system is composed of a star and all the objects moving around it. 4. A galaxy is a collection of many millions of stars. 5. A planet is a large round object that travels around a star, clearing its own orbit. 6. A dwarf planet is a round space object that travels around a star but has not cleared its own orbit.
7. A satellite is any object that orbits a planet. 8. A moon is a naturally occurring satellite. 9. An asteroid is a small rocky object that orbits a star.
10. A comet is a small object composed of frozen gases, ice, rock and dust that can glow and produce a tail.
11. Gravity is a force generated by all objects that attracts all other objects. 12. The Big Bang theory suggests the universe began with an explosion that allowed all the universe’s known matter and energy, as well as space and time, to form.
Questions and Exercises K C
Key Concepts Rewrite the following sentences in your copybook and fill in the blanks.
1. 2. 3.
4.
The ____________________ is all of space and everything in it. A ______________________ is a large ball of gas that gives off light and heat. A ______________________ is a space object that travels around a star, clearing its own orbit.
A ______________________ ______________________ is a space object that travels around a star but has not cleared its own orbit.
