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Earth and Space 6-8 / Week 12 / Sky Night
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Week 12 · Design a Solar System Model

Sky Night

Sky Night: The family tour
// Criteria, constraints, build, measure, improve
⏱ about 20 min

Sky Night: The Family Tour

Saturday evening, the family lines up at the paper Sun. Rocket holds the report. Raven holds the tape measure.

"Mercury," Rocket announces, two steps in. "Twelve centimeters here, 57.9 million kilometers for real."

They walk. The inner planets pass in a few steps. Then the long stretches begin.

"What do you notice?" Raven asks at Saturn. "Most of the hallway is empty, just like most of the solar system."

At Neptune, a grown-up measures from the Sun. "Nine meters and one centimeter." Rocket pumps a fist.

Nova glides to the window. "No Moon yet," she says. "Near third quarter it rises around the middle of the night." Raven writes "not up" and the date. Rocket smiles. "Not the last entry. The log keeps going."

  1. Engineers define a problem by its criteria, what the design must do, and its constraints, the limits it must stay inside.
  2. A scale model shrinks every distance by the same rule. At a hallway scale, NASA's distances put Neptune about 9 meters from the Sun and Mercury at 12 centimeters.
  3. One scale cannot show distances and sizes together. An honest model labels a second scale for sizes.
  4. Testing by measuring, then improving and retesting, made the model better.
  5. Models let us study systems too large, too small or too old to see directly, from a spinning Earth to deep time.
◇ FAMILY TOUR AND MOON CHECK
Give the family the tour from the Sun to Neptune. At each marker, say the planet's name, its model distance and its real distance from NASA's table.
Let a family member measure one marker from the Sun with the tape and check it against your plan.
Read your report's conclusion aloud at Neptune. Then ask each person which week's model they liked best.
If the Moon is up, sketch its shape from your known spot for the Moon log. If not, write "not up" and the date. Cloudy backup: do the tour again with a younger child leading.
For a grown-up
Night observation happens only with you, from the yard, porch or a window, in a known spot. Bring warm clothes and a flashlight for the path.
The model is on the floor of a hallway, room or yard away from roads. Please help remove tape and markers after the tour so no one trips.
The data come from NASA's Planetary Fact Sheet at nssdc.gsfc.nasa.gov and OpenStax Astronomy at openstax.org. Thank you for twelve weeks at the Sky Deck.
Safety first
Walk the model, never run. String and tape stay on the floor.
Small markers stay away from younger children and out of mouths.
Stay in your known spot for the Moon. Never cross a road or climb for a better view. The flashlight points at the ground.
THINK IT THROUGH
  • Read the question.
  • Tap your answer.
A visitor asks why the inner planets are so close together in the model. What is the best answer?
A visitor asks why the markers are all the same size. What is the honest answer?
Sky Night checkTrue or false?
Criteria describe what a design must do.?
Measuring the markers tested the model.?
The Moon log ends with this course.?
WHY THIS EXERCISEObserving and modeling do not stop when a course does.
Draw your family on the tour, strung out along the model from the Sun to Neptune. Add tonight's Moon in the window, or write not up.
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