Activity

How Big is the Solar System?

Summary

How long would it take to travel to the Moon? Could you travel to the edge of the Solar System and beyond? In this activity students learn about the size of the Solar System, beginning with the Earth and Moon and reaching out to encompass the entire Solar System.

Goals

  • Develop an understanding of the scale of the Solar System, starting from the closest object to the farthest.
  • Use numeracy skills to calculate a scale distance model of the Solar System
  • Use numeracy skills to calculate how long it would take to travel to different parts of the Solar System.  

Planning

Materials List

  • 4-metres string
  • Marker Pen or stickers
  • Measuring tape
  • Calculator

Instructions

  1. Ask for two volunteers, one will hold the globe the other will hold the "Moon". Ask the group how far they think the Moon lies from the Earth. The volunteers should move closer or farther apart as directed. 
  2. Let the students guess a few times, then explain that you could fit 30 Earths into the space between the Moon and the Earth! It is 239,000 miles!
  3. Measure the diameter of the globe you are using and ask the students to multiply this number by 30. Measure the distance on the floor to demonstrate the exact distance to scale. How long do the students think it takes to travel this distance in a rocket?

In 1969 it took the astronauts over 4 days to travel to the Moon. Today, the fastest rocket in the world is called New Horizons. New Horizons travels at amazing speeds of around 36,373 miles per hour.

4. Ask your students to work out how long it would take to travel to the Moon aboard New Horizons.

239,000 ÷ 36,373 = 6.57 hours

5. Now ask the students what is the closest object to the Earth beyond the Moon. In the next part of the activity they will learn the size of the Solar System by measuring the distances between the planets.

6. Get a piece of string and either draw a thick stripe or place a sticker on the string near one end. This will represent the Sun.

7. Now use the values in the table below to demonstrate the distances between the planets in the Solar System

Planet Distance from Sun (miles) Distance (cm)
Mercury 35 000 000 3.5
Venus 67 000 000 6.7
Earth 93 000 000 9.3
Mars 142 000 000 14.2
Asteroid Belt 297 000 000 29.7
Jupiter 484 000 000 48.4
Saturn 889 000 000 88.9
Uranus 1 790 000 000 179
Neptune 2 880 000 000 288
Pluto/ Kuiper belt 3 670 000 000 367

8. Measure the distance from the "Sun" (marked on your string) to Mercury using the values on the table above. Draw a dot on the string with the marker pen or use a sticker to represent Mercury.

solarsys_string-300x200.jpg

9. Next measure the distance from the "Sun" to Venus and mark it on the string. Continue until you have marked off the distance to each planet (and dwarf planet, Pluto).

10. Now ask for ten volunteers to come and act as the planets, the asteroid belt and Pluto within the Kuiper Belt. Ask them to stand on one side of the string and hold their thumb over the small point representing their assigned planet.

solarsystem_scale-300x290.jpg

Students demonstrating the distances between the planets in our Solar System.

Next Steps

  1. Discuss the activity with the students. Were there any surprises? Look how empty the outer Solar System (from Mars to Pluto) is and how crowded it is in the inner Solar System (between the Sun and Mars). Why do they think this is? 
  2. Looking at your model of the Solar System, why do you think the planet Venus can outshine giant Jupiter in the night sky despite being much smaller?
  3. Our scale model of our Solar System shrinks the distance between the Sun and Pluto to 1 cm from 10 million kilometers. How much smaller is our scale model than the actual Solar System?
  4. If it takes around 7 hours to travel from Earth to the Moon aboard New Horizons, how long would it take to get to Mars, Jupiter or even Pluto?

Now the students have an idea how long it takes to travel between the planets, and the stars are even farther away. Travelling in New Horizons, it would take almost 30 million years to travel to the nearest star. Obviously this isn’t possible in one lifetime, but luckily for us we have telescopes. Telescopes are our only real instrument for studying the Universe beyond the Solar System.

Use the LCOGT telescopes or image gallery to explore the distant Universe; take a look at the variety of astronomical objects that we don’t find in our Solar System, from star clusters, to clouds of colourful cosmic gas and giant galaxies.