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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?

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

2

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

the average distance between Earth and the sun

3

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

distances in the solar system

4

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

solar system < Milky Way Galaxy < universe

5

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

brightness

6

What are the largest known structures in the universe?

filaments and walls outlining voids

7

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

stars

8

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

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

9

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

the universe

10

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

the Earth-moon system

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?

the Earth-moon system

12

Which is a grouping of many stars?

a galaxy

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?

kilometer

14

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

Which distance measurement is most useful in the solar system?

astronomical unit

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?

light-year

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?

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

17

Why is it difficult to detect planets orbiting other stars?

because they are so small and so far away

18

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

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

19

The Milky Way is which of the following?

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

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

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