Activity 13—THE PLANET URANUS

1 NAME:_____ HOME LOCATION:_____ 69 Activity 13 THE PLANET URANUS These activities are designed to work with the Starry Night software that comes with your text, from any home location you choose, and with the current date and time, unless indicated otherwise. You may always revert to factory default settings by clicking FILE/ preferences, then selecting factory defaults as needed. You may also undo a command or series of commands on the PC by clicking the back button at the top left of the button bar. You should refer to the key given at the beginning of this booklet for clarification of on screen buttons, controls, and functions. PC button bar items can all be accessed through the menu.

2 Right click on the PC is equivalent to control click on the Mac. All activities assume that OpenGL graphics capabilities are enabled on your computer. PART 1: FINDING URANUS You should begin this Activity at sunset. An easy way to do this is to click the drop-down menu to the right of the date & time field on the control panel, and select sunset. Look toward the west by clicking the W viewing direction button located on the button bar across the top of your screen, or by simply keying in the letter W (Mac users should refer to the button bar commands given at the beginning of this booklet). The screen will pan toward the west. Select a playing speed of 300 normal time by clicking the drop-down menu at the right of the time speed field.

3 Click the STOP time mode button when the Sun has set, the stars have come out, and dusk is almost over. Then click on the constellations button to show the constellations. Click the FIND tab on the left side pane. A list of planets should appear. Those that are highlighted are currently up in your evening sky. Those that are not highlighted are not up in the sky at this time. We wish to find the PLANET URANUS . If URANUS is highlighted (see footnote if not highlighted)*, double click or right click on it (control click for Mac) and select center. This will pan the screen and center URANUS . You can now zoom in on URANUS either by using the zoom control at the far right of the control panel, or by right clicking (control clicking for Mac) on the highlighted listing in the FIND side pane and selecting magnify.

4 *If URANUS is not currently highlighted, you will need to move time forward to a time when URANUS will rise in the east. Start by looking toward the east by clicking the E viewing direction button located on the button bar across the top of your screen. Select a playing speed of 300 or 3000 normal time by clicking the drop-down menu at the right of the time speed field. Click the STOP time mode button when the PLANET URANUS becomes highlighted in the FIND side pane listing. It may be that URANUS is up during the day. If the Sun rises before URANUS does, then click the daylight button on the button bar. This will keep the sky dark so you can see the stars and constellations. Once URANUS has risen, double-click on it.

5 This will pan the screen and center URANUS . You can now zoom in on URANUS either by using the zoom control at the far right of the control panel, or by right clicking (control clicking for Mac) on the highlighted listing in the FIND side pane and selecting magnify. Click the information icon (i) in the side pane to read a short description of the PLANET URANUS . Next, select the INFO tab on the left side pane and click the plus sign (gray arrow for Mac) to expand the different information categories. THE PLANET URANUS 70 Use the information in the OTHER DATA section to complete the following table of URANUS s physical characteristics and compare to Earth. (You will need to know Earth s radius = 6378 km.)

6 To compute percent, divide one value by the other and multiply by 100.) PHYSICAL CHARACTERISTICS: Radius of URANUS : _____km, _____ % of Earth Mass of URANUS : Angular size in arc minutes and seconds as seen from Earth: Orbit size (mean distance from the Sun): Sidereal day (period of rotation): Solar day (noon to noon on surface): Length of year: Complete the following table of URANUS s observational characteristics:* OBSERVATIONAL CHARACTERISTICS: Date, time: Azimuth, altitude: Currently in which constellation: Current apparent magnitude: Max possible magnitude as seen from Earth: Current distance from Earth: Distance at conjunction (aligned with the sun): Distance at opposition (opposite the sun): *For constellation, azimuth, and altitude, see POSITION IN SKY.

7 For Distance from Earth, see POSITION IN SPACE. For everything else, see OTHER DATA. To compute distance at conjunction, take orbit size and add Earth s distance from the Sun of 1 AU. To compute distance at opposition, take orbit size and subtract Earth s distance from Sun of 1 AU. PART 2: URANUS S ORBITAL CHARACTERISTICS Use the zoom control at the far right of the control panel to zoom back out to full-scale view. Right click (control click for Mac) on URANUS and select orbit. This shows URANUS s orbital path as seen from Earth. You will need to click the horizon button on the button bar to get rid of the Earth s horizon should it interfere with your view of URANUS s orbit. You should also click the daylight button to turn off daylight.

8 You should still be locked on to URANUS . If not, right click (control click for Mac) on the PLANET URANUS , and then select center. To maintain the proper perspective, select view/ecliptic guides, then the ecliptic. Start with today s date by entering it in the date & time field of the control panel, or by selecting now from the drop-down menu to the right of the date & time field. Note what constellation URANUS is in, then select a time speed of 1 day and click the PLAY time mode button. If you need to slow down or speed up, adjust the time speed fields as needed. You should be able to see URANUS locked in the center of your field of view, but moving across the star background. You should also be able to complete a full revolution in less than a minute.

9 Click the STOP time mode button when URANUS has returned to the same constellation and note the date. Use this information to complete the following table. THE PLANET URANUS 71 VIEWING URANUS S RELATIVE POSITION: Constellation URANUS is located in today: Today s date (corresponding to location of URANUS given above): Date when URANUS is again located in same constellation: Length of time it takes URANUS to return to the same place in the sky (subtract the dates given above): *Note that since URANUS is relatively far from the Sun as compared to the Earth, this value will be close to URANUS s sidereal period (year). However, there will be a difference since we are looking at URANUS s position relative to the Earth, which is itself in an orbit around the Sun.

10 PART 3: FLYING TO URANUS Let s see what a day would be like on URANUS . Right click (control click for Mac) on URANUS and select go there. You can animate the journey by first unchecking the only animate intra PLANET changes box under file/preferences/ responsiveness (also, be sure to have your horizon turned on to see the photorealistic surface panorama). Click the W viewing direction button on the button bar, or simply hit the W key on the keyboard. Select 3000 time speed. Click the PLAY time mode button, and observe what a day would look like as seen from the surface of URANUS (actually, URANUS has no solid surface, so it s really the cloud tops we are viewing). Note that due to URANUS s retrograde rotation, the motion appears to be backwards when compared to what we are used to here on Earth (and as it appears for most of the other planets).