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Week 07 · How Far: Distances

Friday

Distances in everyday life
// Walking the solar system one step at a time
⏱ about 20 min

Friday: Distances in Everyday Life

Rocket paces the yard counting under his breath. "Thirty steps to Neptune. How far is that for a real spacecraft?"

"A long way," Raven says. "Spacecraft have flown past, orbited or landed on every planet, but each trip took a long time."

"What do you notice about the inner planets in our model?" she adds. "You could cross them in one step."

Rocket grins. "So a trip to Mars is a short hop, and Neptune is the long haul."

Nova hovers near the Sun ball. "A textbook builds this same model with city blocks," she says. "One block for Earth."

"Then Neptune is thirty blocks away," Rocket says. "That is the whole town." Nova glows. "Now scale means something to you."

Models at the size of a city

OpenStax Astronomy builds an imaginary model by shrinking every distance by a factor of one billion.

In that model, the Sun is nearly 1.5 meters across, about the height of an adult. Earth is 150 meters away, about one city block.

Jupiter is five blocks from the Sun. Saturn is ten blocks, Uranus twenty and Neptune thirty.

At the same scale, the nearest stars would be tens of thousands of kilometers away, on the other side of Earth.

OpenStax notes that cities around the world have built models like this, with the Sun and planets as sculptures blocks apart.

Why distance shapes exploration

OpenStax says spacecraft have flown past, orbited or landed on every planet. Those trips depend on the distances you read this week.

The inner planets are close together, so a trip from Earth to Mars crosses a small part of the system.

The outer planets are far apart. A trip to Neptune crosses about 30 astronomical units.

Light itself needs eight minutes to reach Earth from the Sun. Any signal sent to a distant spacecraft takes time too.

This is why scientists use models and data tables together. The model shows the pattern; the table gives the numbers.

ScaleOne AU becomesNeptune is about
Your walked model1 step30 steps
OpenStax city model1 city block (150 meters)30 blocks
The real solar system150 million kilometers4515 million kilometers
SCALE IN REAL LIFE
  • Read the question.
  • Tap your answer.
In the OpenStax city model, how far is Earth from the Sun?
Why is a trip to Mars shorter than a trip to Neptune?
Why do scientists use a model and a data table together?
Week reviewTrue or false?
One astronomical unit is about 150 million kilometers.?
Light from the Sun reaches Earth in about eight minutes.?
The inner planets are spread far apart and the outer planets crowd together.?
Neptune is about 30 times Earth's distance from the Sun.?
A light-year measures time.?
WHY THIS EXERCISEThese five ideas are the distance half of the scale properties the standard names.
OUR WEEK, IN ORDER
  • ?We read the NASA distance row and found the growing gaps.
  • ?We learned what an astronomical unit is and why a scale matters.
  • ?We walked the solar system across the yard, one step per AU.
  • ?We learned that sunlight is eight minutes old.
  • ?We compared our model with a city-sized one and with real spacecraft trips.
WHY THIS EXERCISEThe week moved from one number to a model you walked to a pattern you can explain.
In the OpenStax city model, how many blocks from the Sun is Neptune? Type the number.
WHY THIS EXERCISEDifferent scales, same pattern. That is what makes a scale model trustworthy.
Try it
Count how many blocks or houses you pass on a familiar walk with a grown-up. Decide where the Sun would sit and where Earth would be.
Write where Jupiter and Neptune would land in your neighborhood at that scale.
Draw a simple map of your street or hallway. Mark the Sun, Earth one unit away, Jupiter at five and Neptune at thirty.

Strong week. Tomorrow is Sky Night: a Moon check and a solar system walk for the whole family.

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