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Planetarium Activity

Turn off the daylight and horizon displays. Use the “Planet” Palette to center on Comet Halley and lock on Comet Halley. Use the “Settings” button to set Orientation to Equatorial. Use the “Zoom” button to zoom in until the field of view is 40°. Set the date to December 1, 2061. Set the time step to 1 day. Step ahead until you pass the time that the tail of Comet Halley seems to be the longest. Then step back and forth in time until you find the date that the tail is longest. Use the Angular Separation Tool to find the angular length of the tail of Comet Halley. Set the cursor on the nucleus of Comet Halley and find the distance of the comet from the Earth. Step forward in time and see how the distance of the comet changes with time. Find the date on which Comet Halley will be closest to the Earth and its distance on that date. Try to explain why Comet Halley isn’t closest to the Earth on the date its tail is longest.

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