# Teaching Modeling of the Universe with an Orrery Planetarium

This post was written by Lesley Anderson, 2021-2022 Albert Einstein Distinguished Educator Fellow at the Library of Congress.

A mathematical instrument maker for King George III of Great Britain, George Adams designed this orrery as a mechanical model of the solar system. This heliocentric model provides the positions for each of the planets and their moons relative to the sun. The drawing demonstrates an understanding of the universe at the time, 1799. It was published just 50 years after the heliocentric model of the solar system was more openly accepted by religious authorities, and the timing was very important because George Adams was known for his work combining science and religion.

Using this drawing, your students can make connections from historical understanding about the universe to the current understanding and models used in astronomy today.

An orrery or planetarium designed by George Adams showing relative positions of the planets in relation to the sun, 1799

First, show students this picture and ask them to record their observations. Encourage students to focus in on each of the nodes and write down their reflections about what these might represent. Next, students could write down the questions that come up as they review this drawing.

Examples of student questions may include:
• What are the labels above each of the orbs and what do they represent?
• What are the different figures labeled on the diagram?
• I notice the mechanical arm at label C. How does this work?

One of the most important aspects of this primary source is the representation of the universe in the form of a model. This is a great opportunity to ask students to share what they can learn about the perspective of the solar system from people in England in 1799 based on this drawing. Ask students how they think this model differs from our current representation of the universe. Direct students to research as needed to gather information about current representations of the universe.

Since a model is a representation used to explain a concept or idea, students could then look at how models have changed and grown over time. For example, this map of the solar system from 1885 includes more planets and celestial objects than Adams’ orrery. Students may also be interested in looking at a different model from the same time period since the presentation of the information may change their interpretation. The same strategy used for the analysis of the George Adams’ orrery can be used for these models so that students can observe, reflect, and question.

For more examples of solar system primary sources, check out this blog post or this primary source set about the cosmos.

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