# Astronomy 115: Homework Assignment #1

Due Date:
• Section 1: Wednesday, Sept. 12
• Section 2: Wednesday, Sept. 12
• Section 4: Tuesday, Sept. 11

For all homework assignments, write neatly and show your work. You will not receive full credit for simply providing answers without showing work. If you are having trouble with a problem, read it again carefully (it may even help to read it aloud.) Office hours and help sessions are also available...but plan ahead!

Staple multiple pages before coming to class. Staplers may not be available in class.

#### The Size & Scope of the Universe (Ch. 1)

1. The following important terms will be used throughout the course. First, write down what the term means to you or how you've heard it before. Then look up the words in your textbook's glossary and give their astronomical definitions, if different. Optional: Draw a picture of each!

• A.) Planet
• B.) Star
• C.) Solar System
• D.) Galaxy
• E.) Universe.

2. The speed of the light is 300,000,000 meters per second (m/s).
A.) Express this number in kilometers per second (km/s).
B.) Use a conversion factor (1 km = 0.6 miles) to find how many miles light moves in one second.

3. If you lived on Equator (eg. in Quito, Ecuador, Nairobi, Kenya or in Singapore) where would you need to look to see the North Star?

4. Chapter 1, Review Question 9.
What is the ecliptic, and why is it tilted with respect to the celestial equator?

5. Describe in your own words what must happen for you to witness a total solar eclipse. On August 21, 2017, a total solar eclipse was seen in the United States. Did you see it? Was it total?

6. Suppose you had a young niece or nephew who asked "Why do we have seasons?" Explain in one paragraph, including a diagram, how you would answer.

#### Getting Experience with Very Large Numbers

7. What is the astronomical origin of these common units of time, from the calendar?

• A.) Year
• B.) Day
• C.) Month

8. How many seconds are there in 1 year? Express your answer in scientific notation. (NOTE: Remember this number, you'll be using it again and again.)

9. The "National Debt" is the total amount of money that the United States has borrowed, and spent in various ways and not yet payed back. Look up the current national debt, in dollars, and write this number in both long form and scientific notation (OK to round the number off).

Optional:Ask your friends if they know the approximate size of the national debt, and write down their responses!

10. The largest Lottery Jackpot ever won in the US was the \$1.5 billion Powerball jackpot won in Jan. 2016. If you won the lottery 1000 times, would you have enough money to pay off the national debt? (Note that 1 Trillion = 1,000 Billion, and 1 Billion = 1,000 Million.)

11. Optional, Extra Credit Download software for your computer or cell phone that lets you see which objects are in the sky right now. (Search for "Planetarium Software") Run the software while outside at night and try to identify some stars an planets. Write a brief (1 paragraph) review of the software, and describe how you used it. Did it work well?