Sun Dogs: A Unit Study on Light & Optics

The Sun Dog Painting attributed to Urban the Painter depicts the sun dogs, or atmospheric halos, that appeared over Stockholm, Sweden, on April 20, 1535. Scientifically known as parhelia, sun dogs appear low in the horizon during parts of the year when light can shine through ice crystals, creating a bright halo around the sun with intense spots of light at 22 degrees on either side. At times these bright spots will extend horizontally creating a “tail.” Sun dogs are explained by the branch of physics called optics.

Optics is the study of light and its behavior. The study of light goes back to ancient civilizations who experimented with reflection. They are also thought to have used lenses to bend light. The Greeks studied light from a geometrical point of view. In addition, they were concerned with how objects were seen, and what gave them their color.

While there was some interest in lenses in the 14th and 15th centuries, they were being studied empirically in the early 17th century. This study lead to the development of the telescope and microscope. Isaac Newton studied the refraction of light and the spectrum of color that resulted when using a prism to decompose white light.

But what is light?

No man has ever been able to explain fully moonlight or sunlight, or any other kind of light. For thousands of years men have known that light can pass through some materials and not through others. They knew that light has some relation to color and to heat; and in fact, they knew a good deal about the way light acts. But no one could answer with complete satisfaction the question — What is light?
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Sun Dogs: A Unit Study on Light & Optics

And perhaps that is the best way to understand light — to understand how it behaves.

By studying light you can learn:

That light travels in a straight line.
That all objects absorb some of the light that falls on them.
That all objects reflect some of the light that falls on them.
That some objects allow some light to pass through them.
That light travels in a vacuum.
That light is a wave.
That color depends on wavelength.
That white light is a mixture of all of the wavelengths.

You can also learn how we see and learn about the various sources of light.

Suggestions

(You’ll find helpful resources below).

Create a notebook to collect everything you learn about light.
Create a timeline showing the advances in optics.
Create biographical pages for those scientists who studied light, detailing their contributions.
Conduct an experiment in each of the areas listed above. You can record the results on science experiment sheets.
Record the visible spectrum of light in order.
Record the electromagnetic spectrum of light in order.
Compare and contrast reflection and refraction.
Use Drawing & Writing paper to draw and label a diagram of the eye, and explain how your eye works.
What are some optical phenomena you’d like to learn more about (like sun dogs)? Spend some time researching and record what you learn.

Additional Resources

Sundog Formation
How they occur.

Optics Timeline
From the National High Magnetic Field Laboratory.

Light Waves and Color
Tutorial helpful for learning about the visible spectrum of light.

The Electromagnetic Spectrum
Wavelengths of light.

The Behavior of Light: Reflection and Refractions
Helpful for comparing/contrasting the two.

Mirrors, Lenses, and Your Eyes
Useful diagrams for explaining how your eye works.

Activities

Investigating Special Properties of Light
Several experiments from Florida State University.

Light 1: Making Light of Science
Series of three lessons from the American Association for the Advancement of Science. Light 1 covers general information and the electromagnetic spectrum.

Light 2: The Lighter Side of Color
Second in lesson series mentioned above covering reflection, absorption, color, and wavelength.

Light 3: All Those Seeing Color, Say Eye!
Third in lesson series mentioned above covering the anatomy of the eye and perception of color.

Bend a Straw with Your Eyes
Simple refraction demonstration.

Make Your Own Rainbow
Uses a prism to see sunlight separated into colors.

What Makes Color
Sample lesson from the publisher of The World of Light and Sound by Dinah Zike (shown below) that covers primary colors, white light, and more.

Geometric Optics
Interactive from the University of Colorado that allows students to observe the effects of changing lens variables.

Lenses and Mirrors
Another interactive from The Physics Classroom.

Self-Guided Tour of the Electromagnetic Spectrum
Interactive from NOVA.

Cow Eye Dissection
Virtual from PBS. Includes excellent eye labeling diagram that can be printed.

Books

The World of Light and Sound by Dinah Zike
One of the Great Science Adventures from Common Sense Press, this title include the study of light. Following an “inquire, discover, and apply” approach, the student creates his own foldables while investigating concepts. You can find a sample lesson at the publisher’s site. One of Cathy Duffy’s Top Picks!