Lunar and Planetary Institute






Seasons

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Activity: Sun Spray: Exploring Seasonal Sunlight Changes


Explore!
Children model Earth's annual passage around our Sun using water-based paint spray and a “human globe.” They explore how the distribution (and directness) of sunlight changes across the globe with seasons. This activity is best completed outside!

The Activity
Begin the activity by asking why we have seasons (information can be found in “About Seasons”). Note correct and incorrect responses to revisit at the close of the activity.

  • Do all places on Earth experience the same season at the same time?
  • Does the Earth's distance from our Sun affect seasons?
  • What is a solstice?
  • An equinox?
  • Do other planets have seasons?
  • Why or why not?

Provide each group of 3 or 4 children with the group materials. The butcher paper circles will represent Earth. Ask them to mark the north pole at some point on the edge of each of their circles. Where would the south pole be, relative to the north pole? Have them mark the south pole in the appropriate location and then draw a line that connects the north and south poles on both sheets. Have them draw a line that marks the equator, perpendicular to the line between the north and south poles. Both sheets should now have lines that divide them into quarters. Label the north and south poles and equator. Have the children measure an angle approximately 23.5 degrees counterclockwise from the north/south line. With a different color marker, draw the line that follows this angle. This line helps to identify the tilt of Earth's axis. Earth spins on its axis, the line that runs from the north to the south pole, but this axis is tilted 23.5 degrees.

Have one child from each group volunteer to be the “Earth.” Ask the other children in the group to hold the two paper circles against the student (one sheet in back and one in front) so that the line measuring 23.5 degrees from the axis runs vertical from the child's head to his or her feet. Earth's north/south axis will be tilted (north at the top!) so that it runs from the child's shoulder toward his or her knees.

Hold the paper circles so that there is some paper above the child's shoulders. Carefully staple the two sheets together at the shoulders (no clothing attached!). Continue to staple the sheets together at the sides (not the bottom), about every 6 or 8 inches along the circumference of the two circles, so that the child is enveloped in the paper Earth, with head, legs, and hands exposed. Form the paper into a wide tube around the child.

Invite the other children in the group to be the “Sun” or “Earth Observers.” The Sun should be stationary. Invite the children to experiment making day/night cycles by moving Earth relative to the Sun. If the children are unsure of the cause of seasons, visit Season Sequences.

  • What direction does Earth's axis point? (Toward the North Star, Polaris)
  • What causes day/night cycles on Earth? (Earth rotates on its axis)
  • What causes seasons on Earth? (Earth orbits/revolves around the Sun)
  • What changes occur as the seasons change?
  • How does the model of Earth orbiting the Sun and the tilt of Earth's axis explain these changes?
  • What about the duration and amount of sunlight? The angle of the Sun's rays striking the surface? Do these properties change through the year?
  • How?
  • Why?

Invite the children to explore how the pattern of sunlight shifts across our globe through the seasons of the year. Have the Earth and Sun stand about 3 feet apart. Earth's axis should always point toward the same location in the classroom, just as Earth's northern axis always points toward Polaris, the North Star. Based on where the Earth and Sun are standing, have each group identify which season it is in the northern hemisphere. Have each group determine where the Sun and Earth should be to represent winter in the northern hemisphere.

Provide the Sun(child) with a bottle of Sunspray , held so that the bottle is level with the “middle” of Earth and the spray will strike Earth horizontally. What does the spray represent? (The Sun's rays) The position of the spray bottle should not change.

Have the Sun spray its “rays” lightly upon the Earth (being careful not to saturate the paper). The Earth Observers should then draw horizontal lines with a marker to delineate the zone of the spray's major concentration. With the marker, label this area “winter.”

Now have Earth move to a spring position (90 degrees counterclockwise). Is the axis still pointed correctly? Invite the Sun to spray a different color of rays on the Earth. The Earth Observers should mark and label this “spring.”

Have the Earth continue walking, making a complete revolution around the Sun, stopping to repeat the spray and labeling process for spring and fall.

When Earth's revolution is complete, carefully slide the paper off and remove the staples from one side. Lay the paper flat. Have each group observe where the Sun's rays fell in each of the seasonal zones.

  • What do they observe about the patterns?
  • Where are the Sun's rays most directly striking in the northern hemisphere summer?
  • Winter?
  • Where are the rays striking in the fall and spring?
  • The word “equinox” means “equal nights” … which seasons have equinoxes?

Extensions

Since Jupiter's axis of inclination is 3 degrees, would it experience seasons in the same way Earth does? Why or why not? Invite the children to experiment!

More Activities

 

Last updated
January 4, 2007

 

Who?
Ages 10–12

How Long?
90 minutes

What's Needed?

• 4 spray bottles, with nozzles only slightly opened. In each bottle mix:
• 1 oz. of colored finger paint; different color per bottle
• 1 teaspoon flour
• 6 ounces of water
• Large star cut-out labeled “Polaris” or “North Star,” suspended from or taped to the ceiling
• Old shirts, one per group, may be provided for activity with paint, if desired

For each group:

• Two 30-inch-diameter circles cut from butcher or banner paper.
• Colored markers (4 per group)
• Protractor
• Meter/yard stick
• Scissors
• Stapler
• Staple remover

Connections to the National Science Standard(s)

Standards A&D (grades K–4): Identify questions about seasonal changes using their own observations. Conduct an experiment using a model to answer questions about patterns of movement of objects in the sky. Understand why the sun, for example, appears to change its path over the seasons. Identify weather changes over the seasons. Critique and communicate explanations.

Standards A&D (grades 5–8): Identify questions about seasonal changes using their own observations. Using a Sun/Earth model, conduct an investigation to explain and predict observations about how objects in the solar system have regular and predictable motion that explains such phenomena as seasons. Understand that seasons result from variations in the amount of the sun's energy hitting the surface, due to the tilt of the earth's rotation on its axis and the length of the day. Critique and communicate explanations.