Small Objects in Penny System Model of Universe

Created by Wyken Seagrave

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Penny System

The Penny System helps us to see the sizes of the main objects in the universe relative to the size of the Solar System by imagining we have shrunk the Solar System down to the size of a penny (or any other coin 2 cm in diameter). More details on the main Penny System page, where you can also see objects in the universe which are not too large and not too small, and we showed them on a map of the Earth.

On this page, you will find objects where were too small to show on the main page. For large objects, see this page.

Small Objects

We saw on the main page that, if we could shrink the whole Solar System down to the size of a penny, it would look like this:

Image of penny by *ade under a Creative Commons Licence

Notice how small the planetary region (shown in red) is in comparison to the penny. But there's a surprise in store...

Planetary Region

In fact, the diagram above actually exagerates the size of the planetary region to a significant degree! To show the size more accurately, let's zoom into the centre of the penny and look at the orbit of the outermost planet: Neptune. It's represented on the diagram by a red dot.

Even in this magnified view, the planetary region is almost invisible, no bigger than a speck of dust on the penny, and the Earth would only be visible under a very strong microscope!

Now let's look at some other objects.

Light Year

A light year (the distance light would travel in a year) would be just over half the size of the penny.

Nearest Star

Looking at things larger than the penny Solar System, the nearest star would be about two and a half pennies away.

Average Galaxy

A typical galaxy would be about the size of the Empire State Building in New York, about 380 metres across.

Image copyright Google Earth

Click image for larger view.

Milky Way Galaxy

The Milky Way Galaxy is actually larger than most galaxies. In our Penny System it would be a flat disc about the size of a city park, 1265 meters across, 15 meters thick and with a central bulge about 20 meters across.

Image copyright Google Earth

Click image for larger view.

For middle-sized objects in the universe, see the main Penny System page

For large objects in the universe, see the large objects page