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Moon Clips
Copernicus & Tycho

How does the look of a crater change at different phases?


The Crater Copernicus

These images were taken with the Yerkes 24 inch telescope.   They show the crater Copernicus from a waning gibbous moon phase to a waning crescent moon phase.  Notice how the appearance of the crater changes dramatically from when the sun's light shines directly on the crater to when it is nearly fully in shadow.  Which phase has the angle of sunlight that shows you the best detail?  You learn something from every angle of the sun's light.  Discuss and write about the details you can see in the crater, the rim, and rays of ejecta in the surrounding moonscape on the different days of the moon's cycle.



Copernicus and Tycho

Imagine the Sun's angle on the Moon as you observe Copernicus and Tycho during changing phases.  These images were taken with a CCD camera and a 90 mm refractor telescope in a backyard setting.  Single craters were clipped out of the images so we could compare the look of their features during different phases.  The numbers in the image names represent the day of the lunar cycle when the image was taken.  It was necessary to collect these images during several lunar cycles to account for bad weather or to find enough available observing time.


Copernicus on various days of the Moon's cycle:   

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near last quarter  <----   near full   <----  near first quarter


Tycho on various days of the Moon's cycle: 

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near last quarter <-- near full <-- near first quarter


  1. Think about how the sunlight is shining on the moon for each of these images.   Record your ideas in words and drawings in your journal. 

  2. Study these 'moonclips' more closely by using the HOU image processing software.  

  3. Make a model of Copernicus or Tycho with clay. Use a flashlight as the Sun and test your ideas. 

  4. Observe the moon during different times of the lunar cycle using binoculars or a telescope.  How do your observations help you clarify your ideas?


What is the Moon's phase for each image?
Study each crater's shadows and bright areas.  Discuss the evidence with your friends.  Decide the phase when each image was taken and create a model and/or an explanation for your conclusions.

Open two more images of Copernicus copernicus_kittpeak.jpg (7070 bytes) and Tycho tycho_kittpeak.jpg (6721 bytes).  These were taken at NOAO, Kitt Peak, by Adam Block.  Adam used a CCD camera and a 0.4 meter reflecting telescope (400 mm or 16 inches).

Tell the phase of the moon for each crater image and explain how you figured it out!  This is a good activity to do with your friends or classmates.  You may have different opinions, and you will learn how each other is thinking if you share your ideas.  You may wish to make models of these craters with clay or play-doh or papiermache.  Consider using a flashlight or the real Sun to represent sunlight shining on the moon. 


HOU Educators: Download these .fts images of Copernicus and Tycho.

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06/05/2002

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