SkyGlobe Planetarium Introduction: This exercise will simulate the night sky and demonstrate a number of principles of the celestial sphere and the motions of the Earth and planets. Getting Started: 1. Login into the network using your Campus Connect ID and password. 2. Open the Astronomy folder on the desktop and double click the SkyGlobe icon. If you are accessing the program from the campus computer lab open Windows Explorer (rightclick the Start button and select Explore) and browse to Software on Drive Y and navigate to \Science\NASC 107 108\KLASSM folder. Finally, double click on the SkyGlobe icon. Working With SkyGlobe: The screen that you see shows the night sky for today s date and time for an observer facing south. The green line along the bottom of the screen represents your horizon, while the white lines are the lines of right ascension and declination. The green dashed line that divides the screen into eastern and western halves represents the meridian. The red line that crosses the screen diagonally is the ecliptic (Sun's path). The faint blue band represents the Milky Way, and constellations are indicated by red lines that connect stars, with the abbreviating of the constellation name in capital letters. Control of the program is achieved through the buttons around the border of the screen. 1. Click to start the Auto Increment of Time. Time (shown in the screen's upper left corner) begins to change forward in 5 minute increments and the display adjusts to reflect the new sky view. 2. Right click. Time changes backward in 5 minute increments. 3. To stop Time movements, click again (as in step 1). 4. Click a few times and watch more stars appear. 5. Right click and watch the dimmest stars vanish. 6. Click and right click a few times to Zoom in and out. 7. Click the,,, or buttons to advance the Month, Hour, Day, or 1
Week. The view adjusts with each action. Time and date in the screen's upper left corner also reflect your changes. Note: You can also change time by year or century, with the, or buttons 8. Try right clicking the M, H, or D buttons to reverse time and date changes. 9. Click to change your view direction to north, south, east, or west. 10. Click on the Elevation bar (found in the right icon bar) to change your View Elevation. The I beam shaped line shows your current view angle, the heavy line is the horizon. Click above the I beam and the view angle will change to the location where you clicked. Right click (on side or the other of the horizon indicator) to change the angle by a single degree. The button at the base of the Elevation bar indicates the view angle 11. Try centering on a specific planet, star, Deep Sky Object (DSO), or favorite constellation: Click on Search (found in the top menu bar) to display the Search menu. Choose stars and then choose Sirius, click the OK button and the sky view adjusts to show Sirius in the screen's center. 12. To Lock a planet in the screen's center, double right click on the object. If you still have Sirius in the center of your screen, double right click on it and then click on the A button. The sky will begin to revolve around Sirius. Click the A to stop the auto mode, and press the = key or double click on Sirius to unlock the display. 13. When you want to quit Click on FILE on the menu bar, then click on EXIT to return to Program Manager. Click on FILE and EXIT to quit Windows. When you are back to the selection menu, choose QUIT to log off the network. Do not turn the computer off. Just turn the monitor off. 2
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Procedure Earth's Rotation: 1. Click E to face east and then click A to auto increment. Describe the motion of the stars relative to the horizon (at an angle, perpendicular, or parallel). 2. Click Location from the menu bar then click Location Menu to change your location to the Equator. Begin the auto increment and describe the motion of the stars relative to the horizon(at an angle, perpendicular, or parallel). 3. Repeat the above procedure to change the location to the North Pole. How do you think the stars will move relative to the horizon? Begin the auto increment and describe what you see. Did you observe what you thought would happen? How many of the stars are circumpolar? Precession: 4. Click to return to today s date. Caution: You must click R twice due to a program bug. If you don t the program will keep resetting the date back to tonight s date when you don t want it to (if the R button looks as though it is pressed in it is enabled). Now click N to face north. Repetitively click J and observe the motion of the celestial pole. Notice that Polaris is moving away from the celestial pole. Stop when the date reaches about 13,000 AD. Which bright star will be near the celestial pole in about 13,000 years? Be sure that you don t leave the R button in a depressed state. 5. Set the date for June 15. Now select Search and then Planets from the menu bar. Select the Sun. What constellation is the Sun located in? If you are not sure which constellation the Sun is located in ask your instructor. Does this match the astrological sign that an individual born on June 15 th you would look up to read their horoscope? What does this tell you about the validity of astrology? 5
Moon's Motion and Phases: 1. Return the view to tonight's date (click R). 2. What is the phase of the Moon for tonight? (Try placing the mouse cursor over the Moon and observe the bottom of the window where object names appear.) 3. Using the arrow keys center the Moon in the screen. Record the right ascension of the Moon from the lower left corner of the screen by centering the cursor on the Moon. Now press the D key and again center the cursor on the Moon and record the right ascension of the Moon. By how many minutes does the Moon's position change? Eclipses: 1. Set the time and date to 9:00 am, Aug. 21, 2017 by clicking and entering the appropriate values 2. Select Locations and then Locations Menu from the menu bar. Select St. Louis, MO 3. Select Search and then Planets from the menu bar. Select the Moon and then double right click on the Moon to lock on the Moon. 4. What was the phase of the Moon? Repetitively click the H button and observe the Moon and Sun. What event did observers in St. Louis witness? What event did observers in Calcutta, India witness? What event did observers in London, England witness? Hint: where is the Sun and Moon relative to the horizon for each location? Press the = key to unlock the screen. 6
Retrograde Motion of Mars: 1. Set the date to Aug 15, 2005. 2. Find Mars. Since the lock feature does not work with planets you will need to use the arrow keys to keep Mars centered in the screen as time advances. 3. Repetitively press on the D key. 4. From Aug 15 th through Sept. 15 th in which direction is Mars moving relative to the background stars (north, south, east or west)? 5. On about what date does Mars first appear to stop moving relative to the background stars? 6. From Oct. 15 th through Nov. 15 th in what direction is Mars moving relative to the background stars (north, south, east or west)? 5. On about what date does Mars appear to stop moving relative to the background stars? Positions of Planets: 1. Reset the time and date to today (click R). What is the name of the line that the planets appear to be placed along? Sidereal Time vs. Solar Time: Center Spica (in Virgo) at the center of the screen (use Search and Stars from the menu bar). Now zoom in on Spica (use a zoom factor of 6.0). Record the right ascension of Spica by centering the cursor on the star. Leave the cursor centered on Spica. Do not move the mouse. R.A. = Press the D key on the keyboard and record the right ascension of Spica's old location and then take the difference between the two readings. R.A. = Diff. = This difference is the amount by which the sidereal day is shorter than the solar day. 7