Activities

Observing Projects

  1. On a dark, clear, moonless night, can you see the Milky Way from where you live? If so, briefly describe its appearance. If not, what seems to be interfering with your ability to see the Milky Way?

  2. Look up at the sky on a clear, cloud-free night. Is the Moon in the sky? If so, does it interfere with your ability to see the fainter stars? Why do you suppose astronomers prefer to schedule their observations on nights when the Moon is not in the sky?

  3. Look up at the sky on a clear, cloud-free night and note the positions of a few prominent stars relative to such reference markers as rooftops, telephone poles, and treetops. Also note the location from where you make your observations. A few hours later, return to that location and again note the positions of the same bright stars that you observed earlier. How have their positions changed? From these changes, can you deduce the general direction in which the stars appear to be moving?

  4. If you have access to the Starry Night planetarium software, install it on your computer. There are several guides to the use of this software. As an initial introduction, you can run through the step-by-step basics of the program by clicking the Sky Guide tab to the left of the main screen and then clicking the Starry Night basics hyperlink at the bottom of the Sky Guide pane. A more comprehensive guide is available by choosing the Student Exercises hyperlink and then the Tutorial hyperlink. A User’s Guide to this software is available under the Help menu. As a start, you can use this program to determine when the Moon is visible today from your location. If the viewing location in the Starry Night control panel is not set to your location, select Set Home Location … in the File menu (on a Macintosh, this command is found under the Starry Night menu). Click the List tab in the Home Location dialog box; then select the name of your city or town and click the Save As Home Location button. Next, use the hand tool to explore the sky and search for the Moon by moving your viewpoint around the sky. (Click and drag the mouse to achieve this motion.) If the Moon is not easily seen in your sky at this time, click the Find tab at the top left of the main view. The Find pane that opens should contain a list of solar system objects. Ensure that there is no text in the edit box at the top of the Find pane. If the message “Search all Databases” is not displayed below this edit box, then click the magnifying glass icon in the edit box and select Search All from the drop-down menu that appears. Click the + symbol to the left of the listing for Earth to display The Moon and double-click on this entry in the list in order to center the view upon the Moon. (If a message is displayed indicating that “the Moon is not currently visible from your location,” click on the Best Time button to advance to a more suitable time). You will see that the Moon can be seen in the daytime as well as at night. Note that the Time Flow Rate is set to 1x, indicating that time is running forward at the normal rate. Note also the phase of the Moon. (a) Estimate how long it will take before the Moon reaches its full phase. Set the Time Flow Rate to 1 minutes. (b) Find the time of moonset at your location. (c) Determine which, if any, of the following planets are visible tonight: Mercury, Venus, Mars, Jupiter, and Saturn. (Hint: Use the Find pane and click on each planet in turn to explore the positions of these objects.) Feel free to experiment with the many features of Starry Night.

  5. Use the Starry Night program to measure angular spacing between stars in the sky. Open Favourites > Explorations > N Pole to display the northern sky from Calgary, Canada, at a latitude of 51°. This view shows several asterisms, or groups of stars, outlined and labeled with their common names. The stars in the Big Dipper asterism outline the shape of a “dipper,” used for scooping water from a barrel. The two stars in the Big Dipper on the opposite side of the scoop from the handle, Merak and Dubhe, can be seen to point to the brightest star in the Little Dipper, the Pole Star. The Pole Star is close to the North Celestial Pole, the point in the sky directly above the north pole of Earth. It is thus a handy aid to navigation for northern hemisphere observers because it indicates the approximate direction of true north. Measure the spacing between the two “pointer stars” in the Big Dipper and then the spacing between the Pole Star and the closest of the pointer stars, Dubhe. (Hint: These measurements are best made by activating the angular separation tool from the cursor selection control on the left side of the toolbar.) (a) What is the angular distance between the pointer stars Merak and Dubhe? (b) What is the angular spacing, or separation, between Dubhe (the pointer star at the end of the Big Dipper) and the Pole Star? (c) Approximately how many pointer-star spacings are there between Dubhe and the Pole Star?

    Click the Play button in the toolbar. Notice that the Pole Star will appear to remain fixed in the sky as time progresses because it lies very close to the North Celestial Pole. Select Edit > Undo Time Flow or File > Revert from the menu to return to the initial view. Select View > Celestial Guides > Celestial Poles from the menu to indicate the position of the North Celestial Pole on the screen. Right-click on the Pole Star (Ctrl-click on a Macintosh) and select Centre from the drop down menu to center the view on the Pole Star. Zoom in and use the angular separation tool to measure the angular spacing between the Pole Star and the North Celestial Pole. (d) What is the angular separation between the Pole Star and the North Celestial Pole? (e) Select File > Revert from the menu and use the angular separation tool to measure the angle between the Pole Star and the horizon at Calgary. What is the relationship between this angle and the latitude of Calgary (51°)?

Collaborative Exercises

  1. A scientific theory is fundamentally different than the everyday use of the word “theory.” List and describe any three scientific theories of your choice and creatively imagine an additional three hypothetical theories that are not scientific. Briefly describe what is scientific and what is nonscientific about each of these theories.

  2. Angles describe how far apart two objects appear to an observer. From where you are currently sitting, estimate the angular distance between the floor and the ceiling at the front of the room you are sitting in, the angular distance between the two people sitting closest to you, and the angular size of a clock or an exit sign on the wall. Draw sketches to illustrate each answer and describe how each of your answers would change if you were standing in the very center of the room.

  3. Astronomers use powers of ten to describe the distances to objects. List an object or place that is located at very roughly each of the following distances from you: 10-2 m, 100 m, 101 m, 103 m, 107 m, 1010 m, and 1020 m.