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How Soon After Sunset Does the Sky Become Dark? *

Time Required Very Long (1+ months)
*Note: This is an abbreviated Project Idea, without notes to start your background research, a specific list of materials, or a procedure for how to do the experiment. You can identify abbreviated Project Ideas by the asterisk at the end of the title. If you want a Project Idea with full instructions, please pick one without an asterisk.


Here's an astronomy project idea from Dr. James Pierce, a professor in the Astronomy Program at Minnesota State University, Mankato: "Determine the length of twilight at different times of the year by observing the time at which certain bright stars first appear and comparing with the sunset time. Beware of variations due to stars appearing at different altitudes. Try using Polaris as a standard. Also note the time at which automatic streetlights turn on. Determine how soon after sunset stars of different magnitude (brightness) appear." (Pierce, 2004) A good book for learning to locate stars of different brightness for this project is The Stars: A New Way to See Them, by H. A. Rey (Rey, 1966) (available at Amazon.com).

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Science Buddies Staff. "How Soon After Sunset Does the Sky Become Dark?" Science Buddies. Science Buddies, 30 June 2014. Web. 1 Nov. 2014 <http://www.sciencebuddies.org/science-fair-projects/project_ideas/Astro_p024.shtml?From=Blog>

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Science Buddies Staff. (2014, June 30). How Soon After Sunset Does the Sky Become Dark?. Retrieved November 1, 2014 from http://www.sciencebuddies.org/science-fair-projects/project_ideas/Astro_p024.shtml?From=Blog

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Last edit date: 2014-06-30


  • Pierce, J., 2004. "Ideas for Astronomy Science Fair Projects," Astronomy Program, Minnesota State University, Mankato [accessed December 01, 2011] http://mavdisk.mnsu.edu/jpierce/scifair.html.
  • A great book for learning the constellations is (and yes, this is the same H. A. Rey who wrote Curious George):
    Rey, H. A., 1966. The Stars: A New Way to See Them, Boston: Houghton Mifflin.

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