The Milky Way rising over a rock arch in Arches National Park, Utah. Credit: Max Seigal, used with permission

Chapter 2 - Understanding the Sky

CHAPTER INTRODUCTION

Have you ever seen the Milky Way in the night sky? You’d have to be far from city lights to see it looking as spectacular as it does in the photo above, and in many cities the lights prevent us from ever seeing it at all, even on the clearest nights. But long ago, before electric lights lit up the night, our ancestors had clear views of the sky both day and night. It was their quest to understand what they were seeing that ultimately led to the modern understanding of Earth’s place in the universe that we discussed in Chapter 1. In this chapter, we’ll explore our view of the sky and how we can make sense of it.

Journal Entry

Observing the phases of the moon

Although we won’t discuss Moon phases until Section 2.3, now is a good time to start learning about them with daily (or nightly) observations. Set aside a couple pages in your journal to make a table with 3 columns and 30 rows:

Column 1 is the date
Column 2 is the time at which you make your Moon observation
Column 3 is for a simple sketch of what the Moon looks like when you observe it

Plan to observe the Moon each day for a month. Each day, fill in one row with the date, time, and your sketch of what the Moon looks like. If it stays too cloudy for you to observe the Moon on a particular date, write “cloudy” where you would have put your sketch.

Note: You will quickly realize that the time the Moon is visible in your sky varies. To find out what time the Moon rises and sets, you can use this web page, entering your city in the box: https://www.timeanddate.com/moon.

Show Teachers Notes

We suggest having students start their Moon observations right away, so that they’ll have at least a portion of a month done by the time you start on Section 2.3; you might even consider having them start this journal activity when you are still covering chapter 1.

Note: The most difficult part of this journal activity is knowing when to look for the Moon in the sky. You can help them with looking up the Moon’s rise and set time for your location each day (per note in the box), so they know the hours in which they could potentially see the Moon.

Group Discussion

Thinking about the Sky

Working as a group, do your best to answer the following questions. Don’t worry if you don’t know all the answers; you’ll learn the correct answers later in this chapter.

Why do the Sun, Moon, and stars rise and set?

Look at the photo to the right. Can you explain what it shows and how it was taken?

Do all parts of the Earth have the same season at the same time, or do the seasons differ for different locations?

What causes the seasons?

What causes the phases of the Moon?

What are eclipses?

What have you seen in the sky that you are curious about?