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## Web Assignment: Learn to Use Sky View Café

### Introduction

When you do not yet know very much about what is up there in the sky it can be difficult to tell what you are looking at. What you need is a place to go to find out what will be up in the sky. Once you know what’s up there you can go out and find it.

In this activity I will introduce you to a powerful tool for finding out what is up in the sky. You can use it to find out when the Sun rises and sets, what the phase of the Moon is, when the planets can be seen in the sky, and what constellations are out at night. I will instruct you about how to do what you need to do to answer the following questions but you must pay close attention! There will be no written instructions handed out.

Go to the following web page: http://www.skyviewcafe.com/. About two-thirds of the way down the page there is a link to “Use the Sky View Café interactive planetarium now.” Clicking on this link will cause a Java application to load.

In order to complete this activity successfully you must be willing to pay attention to the teacher when instructions are given on the screen. Once you have been given a brief introduction to the main features you will be using today you are encouraged to play with this tool as much as you like.

Answer the following questions on a separate piece of paper using complete sentences and neat drawings. Most of the questions have more than one part. Answer all parts of every question!.

1. Set your location to Scarborough, Maine and save it. Briefly describe how this is done on your paper.
2. Set the view to show “Horizon to Zenith” and drag the view to look due South. Set the time and date for today at 12 noon. You can use the arrow keys to change individual digits of the time. Play with this feature with as many of the different digits as you like. When you are done, set the time for today at noon again. Now use the up arrow key to change the day. What happens to the position of the Sun as the days march into the coming months? On what day does the trend in the Sun’s motion reverse?
3. Set the view to “Horizon to Zenith” and the time to “Now”. Set the view to look due North. What is the altitude of the Polaris, the North Star? On the right side of the screen you will see boxes where you can set latitude and longitude. Does the position of Polaris in the sky change at all if you change the longitude? (Just use the arrows to change it). What is the altitude of Polaris if you change the latitude to 15°N? Find the altitude of Polaris for 30°N, 67°N, and 90°N. Is there a pattern relating the altitude of Polaris and your latitude? What is it? Altitude just refers to the distance in degrees of an object from the horizon. (Hint: use the pointer to point at Polaris and read the altitude from the status bar at the bottom of the applet.)
4. Reset your location to Scarborough, ME. Click the check-box to display constellations, show names for the constellations, and turn off names for everything else (the controls for these actions are in the lower-right). Set the view to show “Full Sky - Flat”. Use your list of constellations to identify five bright and/or ancient constellations on each of the following dates during 2009 at 10:00 pm (22:00): Mar 21, Jun 21, Sep 21, and Dec 21. The constellations you choose should be overhead as those are easiest to find. Draw pictures of the outlines for each of the five constellations you choose for each date. Are there any you can see on one date that you can still see on another date? What explains the change in the constellations you can see?
5. Set the view to “Horizon to Zenith” and the time to 12 noon on Mar 21 of this year. Set the view to look due South. What is the altitude of the Sun at this time on this date? Find the altitude of the Sun on Jun 21, Sep 21, and Dec 21. Altitude just refers to the distance in degrees of an object from the horizon. (Hint: use the pointer to point at the Sun and read the altitude from the status bar at the bottom of the applet.)
6. Set the time and date to “Now”. On the right side of the screen find the check-box marked “Ecliptic” and check it. Set the “Sky Color” to Black. Click on “Show Names...” and choose planets. Now use the arrow keys to change the date by placing the cursor on the digit representing the day. Move forward in time and watch how the planets, Sun and Moon on your screen move. What is their motion relative to the line on the screen that is the Ecliptic? What explains this fact?
7. Set the time and date for 7:00 pm (19:00) tonight. What planets are in the sky? Identify the planets and the constellations where they can be found. Also, find out what the altitude of each planet is. Switch views back and forth between “Full Sky - Flat” to “Horizon to Zenith” to get a better idea of what things will look like.
8. Set the time and date for 6:30 am tomorrow (in late January in our location this is about a ½-hour before sunrise). What planets are in the sky? Identify the planets and the constellations where they can be found. Also, find out what the altitude of each planet is.
9. Set the time and date for 12/21/2010 at 03:17. This is the most recent total lunar eclipse visible from Maine. Once you have found the eclipse change the view to “Moon - 8° span”. Choose the “Parallel to Ecliptic” option at the top of the sky window. Use the arrows to go forward and backward in time by minutes. What time is the darkest part of the eclipse? Hint: The time and date I gave you is right in the middle of the darkest part of the eclipse. Using the arrow keys find out what time the Moon enters the brighter part of the Earth’s shadow (called the penumbra). Also, find out when the Moon enters the darker part of the Earth’s shadow (called the umbra). Finally, find out what time the Moon exits the umbra and exits the penumbra. In your response draw a picture of the Moon moving through the penumbra and umbra. Search for lunar eclipses at http://www.skyandtelescope.com/ to see what this looks like.
10. Does the eclipse happen near any bright stars or planets? (Bright stars are given name labels in this application; you will have to turn them on). What stars? What planets? What constellations are near the Moon during this eclipse?
11. Explain how you would use SkyView Café to find out whether there are any planets in the sky on the night of your birthday. Do this and list the planets and the constellations they are in at 9:30 pm on your birthday.
12. Explain how you would use SkyView Café to find out when the Sun rises and sets on your birthday. Do this and write down the answer.
13. Explain how you would use SkyView Café to find out the phase of the Moon on Halloween this year. Do this and write down what it is.
14. Explain how you would use SkyView Café to find out if the constellation Cygnus is visible at midnight on June 21. Do this and write whether it is.
There are additional questions to extend this activity available. They are concerned with planetary conjunctions and oppositions.
Last updated: Feb 22, 2009       Home