Chapter 1

Question 1

North is up in this figure. Can we tell whether the daylight and darkness line at the right is the sunset line or the sunrise line?

Answer 1

It is the sunset line because Earth rotates counterclockwise when viewed from above Earth’s north pole.

Question 2

What is the definition of the astronomical unit (AU)?

Answer 2

the average distance between Earth and the sun

Question 3

What types of distances are typically listed in astronomical units (AU)?

Answer 3

distances in the solar system

Question 4

Which of the following lists is in order of increasing size?

Answer 4

solar system < Milky Way Galaxy < universe

Question 5

Which property of a star is represented by the different sized dots in this figure?

Answer 5

brightness

Question 6

What are the largest known structures in the universe?

Answer 6

filaments and walls outlining voids

Question 7

What forms in the great clouds of gas and dust in the spiral arms of a galaxy?

Answer 7

stars

Question 8

Comment on the line between daylight and darkness on the far right of the figure.

Answer 8

This is the sunset line, because Earth rotates from west to east.

Question 9

Consider the Earth-moon system, the solar system, the Galaxy and the universe. Which is largest?

Answer 9

the universe

Question 10

Consider the Earth-moon system, the solar system, the galaxy and the universe. Which is smallest?

Answer 10

the Earth-moon system

Question 11

Consider the Earth-moon system, the solar system, the galaxy and the universe. Which has the least empty space relative to the size of the objects it is made of?

Answer 11

the Earth-moon system

Question 12

Which is a grouping of many stars?

Answer 12

a galaxy

Question 13

Think about the following distance measurements: mile, kilometer, astronomical unit, and light-year.

In scientific astronomical work, which distance measurement is most useful and most often used for distances ON a planet?

Answer 13

kilometer

Question 14

Think about the following distance measurements: mile, kilometer, astronomical unit, and light-year.

Which distance measurement is most useful in the solar system?

Answer 14

astronomical unit

Question 15

Think about the following distance measurements: mile, kilometer, astronomical unit, and light-year.

Which distance measurement is most useful in measuring the distance between stars?

Answer 15

light-year

Question 16

Think about the following distance measurements: mile, kilometer, astronomical unit, and light-year.

Why are different distance units useful for making different measurements of sizes of astronomical objects and distances between them?

Answer 16

because the sizes and the distances between the objects that astronomers study vary so much

Question 17

Why is it difficult to detect planets orbiting other stars?

Answer 17

because they are so small and so far away

Question 18

What do astronomers think about the possibility of planets orbiting other stars and of them being detected?

Answer 18

A number have been detected, and astronomers feel they are common.

Question 19

The Milky Way is which of the following?

Answer 19

a group of several hundred billion stars of which our sun is a part

Question 20

Choose the option which lists objects from smallest to largest size (left to right).

Milky Way Galaxy, cluster of galaxies, Earth, sun, solar system

Answer 20

Earth, sun, solar system, Milky Way Galaxy, cluster of galaxies