What is an Orbit?

1. PART A: Which TWO of the following statements should be included in an objective summary of the article?

• A. The distance between a satellite and the object it is orbiting varies due to the shape of the orbit.

• B. The use of man-made satellites to take pictures of Earth from space presents a privacy concerns to all humans.

• C. The Earth's consistent and circular orbit around the sun keeps the length of Earth days regular.

• D. Man-made satellites pose a serious threat to the environment that natural objects in space do not.

• E. A satellite is in orbit as long as it is making a recurring elliptical path around another object.

2. PART B: Which TWO details from the text best support the answers to Part A?

• A. "Orbits come in different shapes. All orbits are elliptical, which means they are an ellipse, similar to an oval." (Paragraph 3)

• D. "A constant tug-of-war takes place between the satellite's tendency to move in a straight line, or momentum, and the tug of gravity pulling the satellite back." (Paragraph 5)

• C. "The time it takes a satellite to make one full orbit is called its period. For example, Earth has an orbital period of one year." (Paragraph 4)

• B. "The closest point a satellite comes to Earth is called its perigee. The farthest point is the apogee." (Paragraph 4)

• E. "If the forward momentum of one object is too great, it will speed past and not enter into orbit. If momentum is too small, the object will be pulled down and crash." (Paragraph 6)

3. Part A: How does the author's discussion of the relationship between momentum and gravity contribute to an understanding of orbits?

• A. The author shows how orbits are possible by explaining that gravity has to offset an object's momentum in order for the object to stay in orbit.

• B. The author emphasizes how orbits can become unstable over time if a satellite's gravity becomes too strong.

• C. The author proves that an object's gravity is more important for keeping a satellite in orbit than its momentum.

• D. The author emphasizes how satellites can become dangerous to the objects they orbit if their momentum is too strong.

4. 4. Part B: Which line from the text best supports the answer to Part A?

• A. "An object in motion will stay in motion unless something pushes or pulls on it." (Paragraph 5)

• B. "Without gravity, an Earth-orbiting satellite would go off into space along a straight line." (Paragraph 5)

• C. "An object's momentum and the force of gravity have to be balanced for an orbit to happen." (Paragraph 6)

• D. "If momentum is too small, the object will be pulled down and crash." (Paragraph 6)

• A

• B

• C

• D