Objectives:

The objectives of this lab exercise are to get you familiar with and let you experiment with the SkyGazer software packaged with your textbook, and also available on the Physics lab computers.

Introduction: 

SkyGazer is a planetarium program which enables you to observe the positions of celestial bodies (planets, stars, galaxies ...) in the sky from any position on Earth and at any time. The software package also has interactive pre-packaged activity files and instructive animations.

Initial Setup

Open the SkyGazer program (from the Internet Explorer Favorites menu in the Physics lab)

A large window should appear, (labeled Sky Chart), showing the horizon with a portion of the sky visible. You should also see a smaller window with a clock labeled Time and the Location panel showing a map of the world with your location marked. The location has been pre-set for Vancouver. It may be easily changed by opening the Control menu and choosing Set Location.

If the Sky Chart window is not full-screen, change it to full-screen by clicking the middle small icon at the top right of the window. It is probable that there are no stars in the sky, as the time of the simulation is your actual time of day, as you may see from the Time window.

Observe the position of the Sun and of the parts of the world that are in daylight.

Close the Location panel.

Time

On the Time window, click on the Start button, causing the time to march forward. Eventually, the simulated time should become late enough that the sky begins to darken and stars become visible. If the time is incrementing too slowly, click on Stop, and then click on the button directly below the Start/Stop button, which contains a time interval, (probably 1 minute). You can then select a new time interval; the larger the time interval, the quicker time will flow during the simulation. Unless you have a very slow computer, I recommend that you select 5 minutes as the time interval. After you have selected an appropriate time interval, click the Start button again and wait for nighttime.

Navigation

After the Sun sets, you should see stars in the sky. Notice that you are only looking in one direction, and therefore you will not be able to see the entire sky. It is hard to simulate the sky on a small computer screen, so it may take a while to adjust and recognize some constellations. Once the sky is nice and dark, click Stop on the Time window, and have a look around. If you want to look in other directions, use the arrow keys on your keyboard to pivot to the right, left, up, or down. You can also use the horizontal and vertical sliding bars. There are also zoom out and zoom in buttons, located on the bottom left of the Sky Chart window. If you zoom out far enough, the horizon will be noticeably "warped," as if you were looking through a fish-eye wide-view lens.

Constellations

Click on the Control menu and open the Display panel. (All panels are accessible from the Control menu .) Click on the seventh icon (with the Big Dipper shown). The individual constellation regions in the sky should be partitioned, and "stick figures" should be visible where dotted lines "connect the dots." To turn off this figure, simply click on the Big Dipper-icon again (in the Display panel). Note that any icon in the Display panel that is darkened will be activated within the Sky Chart window, and any icon that is mostly white will not be activated. If you want to see the actual figures that the constellations are suppose to be, activate the eighth icon in the Display panel, (this icon shows a cartoon of a man). The originators of the constellations surely had great imaginations to see these figures in the stars! To see the names of these constellations, click on the Chart menu, select Chart Labels, and then select Constellations. (Note the many choices you have available.)

Planets

In addition to stars, SkyGazer can also simulate the position of the planets if the Planet icon (third icon) in the Display panel is activated,. The best method of finding a planet is by looking along the ecliptic, (the path traced out by the Sun throughout the year). If you want the ecliptic shown in your Sky Chart, click on the Display menu, select Reference Markers and Ecliptic Equator. If not activated by default, you also need to activate the 10th icon in the Display panel, (the icon having a straight line and a few points drawn). You should now see the Ecliptic line drawn in the Sky Chart, with the months labeling the position of the Sun throughout the year. Navigate along the ecliptic from the eastern horizon to the western horizon, looking for planets. Planets such as Jupiter, Saturn, Venus, and Mars should appear as very bright big dots. If you want to see the dim planets, click on the View/Center Planet menu and pick the planet. (If the planet is not visible, SkyGazer will find it anyway!)

Location and Date

Do you want to see what the sky looks like in a different part of the World? In the Control menu, click on Set Location. You should see a window appear containing an image of the globe. You can pick a new location by simply clicking the mouse while the mouse pointer is positioned on the new location. If you double click, the selected location will be in the center of the figure, allowing you to "turn the globe" such that you can select a location that was initially on the "back side" of the globe. You can also select a location by either typing in the name of a major city or by selecting a city from the List Cities button. After you have selected a location, click on the OK button. You should see the sky change, and your new latitude and longitude should be shown in the bottom right of the Sky Chart window. Note that, in a similar fashion, you can change the time, day, month, and even the year of the simulation by clicking on the Control/Set Time option.

Horizon

If you are frustrated that the hilly horizon covers up a significant fraction of the sky, you can draw your own horizon and make it as flat or hilly as you prefer. Click on the Control/Define Horizon menu. Following the directions that appear on the Horizon window, draw in your horizon and then click on Apply and then OK.

Further: Demos and Tutorials

In addition to the sky simulator you have been using , SkyGazer also contains many Demos and Tutorials. To view the Tutorials, click on the Explore menu. You should see a list of tutorials, including Wobble of the Earth, Paths of the Planets, and Phases of the Planets, (including Phases of the Moon). Access the many Demos (such as Mars in Retrograde Motion) by clicking on the File menu/Open Settings and look in the Demos folder. Feel free to explore with these demos and tutorials as they make understanding the initially complicated concepts of phases, eclipses, retrograde motion, and seasons more easily understandable.
You can always return to the startup condition be clicking on the File menu/Recent Settings.