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Size, Motion, Distance - Light Speed Ahead!

There are various methods that scientists use to measure distances in space. Using miles or kilometers would require using such large numbers that we would not be able to understand it. The astronomical unit (AU) and the light year are very useful methods. Click on the links to learn what each of these means.

Let’s examine how long it would take to get to other areas of our universe.

  • Pluto (our farthest planet) = 327 light minutes (0.000624 light years)
  • Alpha Centauri (our next closest star) = 4.35 light years away
  • Andromeda (our neighboring galaxy) = 2,000,000 light years away

Space Travel is Not a Walk in the Park!


  • Timer (needs to display seconds)
  • Light time travel chart (below)


  1. Review information about light years.
  2. Using the light time travel chart and a timer, begin walking to Mercury.  Pretend YOU are moving at the speed of light.
  3. Stop and discuss what you observed and did.
  4. Repeat Steps 2 and 3 for each planet in our solar system.  You might not end up walking all the way to Pluto.

Analysis Questions:

  1. Why did we not visit all the planets?
  2. Why did we not leave our solar system, and walk to Alpha Centauri?
Planet/Star Light Years
Mercury 0.000006 (3 light minutes)
Venus 0.000011 (6 light minutes)
Earth 0.000016 (8 light minutes)
Mars 0.000024 (12.5 light minutes)
Jupiter 0.000082 (43 light minutes)
Saturn 0.000151 (79 light minutes)
Uranus 0.000304 (160 light minutes)
Neptune 0.000476 (250 light minutes)
Pluto 0.000624 (327 light minutes)
Alpha Centauri (nearest star other than Sun) 4.35 light years
utah state board of education This Sci-ber Text was developed by the Utah State Board of Education and Utah educators.