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How Soon After Sunset Does the Sky Become Dark?

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Areas of Science
Time Required
Very Long (1+ months)
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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).


  • Pierce, J., 2004. Ideas for Astronomy Science Fair Projects, Astronomy Program, Minnesota State University, Mankato. Retrieved December 01, 2011.
  • 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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MLA Style

Science Buddies Staff. "How Soon After Sunset Does the Sky Become Dark?" Science Buddies, 20 Nov. 2020, https://www.sciencebuddies.org/science-fair-projects/project-ideas/Astro_p024/astronomy/how-soon-after-sunset-does-the-sky-become-dark. Accessed 7 June 2023.

APA Style

Science Buddies Staff. (2020, November 20). How Soon After Sunset Does the Sky Become Dark? Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/Astro_p024/astronomy/how-soon-after-sunset-does-the-sky-become-dark

Last edit date: 2020-11-20
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