In this activity, you'll get a sense for how far space really is from the surface of Earth by stacking coins on a map. You can compare this to the distances of places you know and even see how far it is to the International Space Station.

Materials for the activity laid out on a table


1. Think about where space begins

We often think of space as being very far away. Planets are many millions or even billions of miles away, and stars are so far away their distances are measured in light years. (A light year is the distance light travels in a year and is equal to six trillion miles.) But how far is it really from the surface of Earth to space?

About the images:

  1. Dedicated in 1948, the 200-inch Hale Telescope at the Palomar Observatory in Southern California, shown here, was the largest effective telescope in the world until 1993. Credit: Caltech/Palomar | › Learn more
  2. An image taken in October 2018 shows the International Space Station flying above Earth. Credit: NASA | › Full image and caption
A ruler is shown beside the scale on a printed out map

2. Find and measure scale distances on your map

Pull up a map of your local area online, such as on Google Maps or Bing, and print it out*. Be sure that there's a scale bar visible, usually in the lower left or right corner. (You can also download and print out this Los Angeles area map.)

Locate the scale bar on your map. This shows you the distances represented on your map. Use a ruler to measure the length of the scale bar in millimeters. In this example, 21 mm represents 25 miles.

*If you have a tablet computer, you can also pull up an online map and measure the scale bar directly on your tablet screen. In this case, you may want to take a screengrab of the map and access it from your tablet's image gallery so the map view doesn't change while you're working with it.

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A person writes out their calculation on a piece of paper

3. Calculate the scale distance to space

You now know that the distance to space is 62 miles. Using the measurement you made in the last step, calculate how many millimeters represents 62 miles on your map. If needed, you can simplify your calculation by figuring out how many millimeters represent 60 miles.

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Coins stacked on top of a printed map of the Los Angeles area

4. Stack coins to space

Place your map on a flat surface. Stack coins on top of your map until they reach the height you calculated in the previous step. This height represents the scale distance to the beginning of space.

Remember: if your ruler doesn’t start with zero mm at the edge, be sure to align the zero mark to the bottom of your coin stack.

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A higher stack of coins is shown on top of a printed map of the Los Angeles area

5. How far up is the International Space Station?

Use the same process to stack coins that show the distance to the International Space Station, which orbits 250 miles (400 kilometers) above Earth’s surface.

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6. What on Earth is as far away as space?

Find a location on your map that is equal to the distance to space or the International Space Station. Use a map that displays a larger area if needed.

The Moon is shown beyond hazy bands of white and blue from the limb of Earth's horizon.

7. How far away is the Moon?

While space starts 62 miles above Earth’s surface, the Moon is much farther away. On average, it orbits 238,855 miles (384,400 kilometers) from Earth. How high would you have to stack coins on your map to represent the distance to the Moon?

About the image: From his vantage point in low Earth orbit aboard the International Space Station, NASA astronaut Randy Bresnik pointed his camera toward the rising Moon and captured this beautiful image on August 3, 2017. Credit: NASA | › Full image and caption