Constellation Transparency Set

Introduction

Introduce constellations and present some interesting views of four different constellations through the use of overhead transparency sets.

Concepts

• Astronomy
• Constellations
• Stars

Materials

Safety Precautions

Follow all normal classroom guidelines.

Disposal

The constellation transparency sheets may be saved for future use.

Procedure

1. Place the first transparency showing the stars in the Gemini Twins Constellation on the overhead projector and ask students what they see. Note: The first transparency is labeled GT 1 on the bottom right-hand corner.
2. Remove the first transparency from the overhead projector. Place the second transparency labeled GT 2 on the overhead.
3. Remove the second transparency from the overhead projector. Place the third transparency labeled GT 3 on the overhead projector to show a different representation of the same constellation.
4. Superimpose the first three transparencies on top of each other for comparison.
5. Place the fourth transparency labeled GT 4 on the screen to show the Gemini Twins.
6. Remove the Gemini Twins transparency set from the overhead projector. Repeat steps 1–5 with the remaining transparency sets: Leo the Lion (labeled LL 1–4), Orion the Great Hunter (labeled OGH 1–4), Ursa Major, the Great Bear (labeled UM 1–4).

Teacher Tips

• This is an excellent activity to use when introducing your astronomy unit. Accompanied by some mythology and folklore, this demonstration can be a real attention grabber for students.
• Encourage students to go out at night, look up at the sky and try to locate the Great Bear, the Gemini twins, Leo the Lion and Orion the Great Hunter constellations.
• The use of student star charts (Catalog No. AP5235) allows students to gain a better understanding of the constellations.

Discussion

Constellations are clusters of stars that poets, farmers and astronomers have created over the past 6,000 years. The constellations are in the shapes of heroes, kings, queens, monsters and gods. Folklore has played a major role in the naming of several constellations. A good example is seen in the folklore associated with the Gemini Twins (Castor and Pollux) constellation. Castor was killed in battle and his brother Pollux, in his grief, asked the great god Jupiter to let him share the same fate. Jupiter took pity on him and put the Gemini twins up in the sky where they could be together for all time. The constellations used in this activity, The Great Bear (Ursa Major), the Gemini twins, Leo the Lion and Orion the Great Hunter are a few of the most famous and easiest to find constellations.

As Earth rotates, constellations, such as the Great Bear (Ursa major) and others in the Northern sky, appear to circle around the North Star (Polaris). Because these constellations circle around Polaris, they are known as a circumpolar constellations. The constellations appear to move because Earth itself is moving. Constellations appear to complete one full circle in the sky in just under 24 hours as Earth rotates on its axis. Constellations also appear to change positions in the sky throughout the year as Earth revolves around the sun. Circumpolar constellations are visible all year long, while other constellations are not. As Earth orbits on its axis, non-circumpolar constellations disappear while others come into view. For example, Orion the Great Hunter is only seen in the winter in the Northern Hemisphere. During the summer in the Northern Hemisphere, the daytime side of the Earth faces Orion. Maps of the visible constellations in Earth’s sky during different seasons of the year for the Northern Hemisphere can be found in Figures 1–4.

The dependence on constellations in the sky has become a major part of many cultures. In the past, farmers around the world knew that most crops must be planted in the spring and harvested in the fall. In some regions, there was not much differentiation between the seasons. Since different constellations were visible at various times of the year, they would use them to tell what month it was. Historians suspect that many of the myths associated with the constellations were actually invented to help farmers remember them. When farmers saw certain constellations, they would know when it was time to begin the planting or reaping process.

In our modern world, many of the constellations have been redefined so now every visible star in the sky is in a constellation. In 1929, the International Astronomical Union (IAU) adopted the constellation boundaries that define the 88 official constellations that exist today.

References

Gross, G. R., Holzer, M. A., Colangelo, E. A. A Demo A Day—A Year of Earth Science Demonstrations; Flinn Scientific, Inc: Batavia, IL, 2001, pp 40–44.