Physics & Physical Science Demos, Labs, & Projects for High School Teachers

Our Solar System to Scale

Posted on: April 18, 2010

Tomorrow the students learn just how big our solar system is and just how small we are.  We will use the attached worksheet to calculate the percent distance from Pluto for the planets in our solar system and our nearest neighbor, Proxima Centauri.

Solar System – Size and Scale

To make this lesson really stick, we first calculate the percentages, then we lay out a long 100 meter tape outside.  Students volunteer to be objects and they get a card with the picture of that object on it.  Now we place them on the scale based on their percentage distance.  The Sun is at the zero point, Mercury being only 1% of the distance to Pluto is at 1 meter.  Earth is at 3 meters, Mars is at 4 meters.  Jupiter jumps to 13 meters from the Sun.  Pluto is at the 100 meter mark.

In addition to the vast distances, I then discuss how big these objects would be at this scale.  The Sun, as huge as it is, is only 2.4 cm or 1 inch in diameter.  The Earth would be 0.2 mm, about the size of the period at the end of a sentence.

We discuss how long it takes to get from the Earth to Mars (a 6 month trip by rocket).  The people who are Earth and Mars are fighting for space on the tape, it’s crowded near the Sun.  After they start to get a sense of scale, I hit them with this.  At this scale, the next closes star,  Proxima Centauri, is 676 km (420 miles) away, or roughly the distance from Philadelphia to Portland, Maine.


8 Responses to "Our Solar System to Scale"

I am well out of HS and yet I can still learn a few things from your blog! Helping to put it in perspective might be Part 1 and 2 NOVA’s last episodes (“Hunting the Edge of Space” ). Are you taking them to see Hubble 3D?!!



My dad (who teaches as well), actually developed a really cool solar system model for his astronomy class he teaches. I of course, then stole his idea and did it myself. It is really cool and actually got the kids pretty impressed and maybe actually finally made the point of how big the solar system is, and how small we are.

Basically, we did a 1,000 yard solar system. At this scale, the Sun is the size of a volleyball. You can then use real things for the planets in approximate scale: Mercury is a poppy seed, Venus and Earth are peppercorns (my dad used coriander seeds), Mars is another poppy seed, Jupiter and Saturn are Lindt chocolates (we used red for Jupiter and Yellow for Saturn), Neptune and Uranus are peanut M&Ms (blue and green), and Pluto was a grain of salt. For the asteroid belt we took some more salt and threw it over our shoulder. By the time we got to Pluto, the kids were pretty impressed, plus by measuring the solar system in yards, each step is about one yard, so we could walk and count to the next planet. It was pretty neat, and the kids liked getting out of the classroom.

I like the objects for the planets, but my 100 yards had me at the extremes of the school property. At a thousand yards, we’d be playing in traffic.

[…] are looking for new and innovative ways to teach science to their students. Recommended posts: “Our Solar System to Scale” and “Final Exam – […]

nice model..

After calculating the original scale for the solar system and completing the activity, I have asked my students to choose a local map and create and apply their own scale. Then they measure and diagram the solar system onto the local city or county map that they have chosen including measurements, labels, key, etc.

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