Education and
Public Engagement
at the Lunar and Planetary Institute
Sky Tellers - The Myths, the Magic, and the Mysteries of the Universe

Activity: Celestial Circles

Who?
Ages 8–14

How Long?
60 minutes

What's Needed?

For each group or pair of children:

Experience!

Children 8-14 model Earth’s axial tilt and movement around our Sun to reinforce their knowledge about the “fixed” North Star and the apparent movement of the zodiac and stars through the year. This activity is an extension to Zodiac Track.

The Activity

Before You Begin
Obtain night sky charts for your location for different seasons of the year. The charts should show the Zodiac constellations. Sky and Telescope offers an interactive Sky Chart that can be generated and printed easily using a local zip code.

The Activity
Review the signs of the zodiac with the children. Invite the children to illustrate what is happening using the constellations on the wall and using themselves to represent Earth.

It is important for the children to understand that the stars that we see making up a constellation exist in three dimensions. (The stars are not in the same plane — as with a drawing — although we perceive them that way from our location on Earth)

Have one child at a time (or small groups of children) stand in the center of the room (under Polaris) representing Earth. Place the lamp between the child (Earth) and the constellations on one wall. Turn on the lamp. Have the child rotate.

Allow other children to try the experiment and make observations.

Distribute the “night sky charts.” What zodiac constellations are visible in the night sky during each of the seasons?

Invite the children to experiment with positions and movement of Earth and the Sun relative to the constellations to see if they can create a model that replicates the changing nighttime viewing of the zodiac signs through the year.

Remind them that in their model the Earth should rotate once a day; Earth’s northern axis points to Polaris; and the Earth revolves around our Sun once a year.

Ask the groups to share their models when they think they can illustrate why the zodiac constellations observed in the night sky change through the year. Have all the children participate in reviewing the models.

The children should have observed that when they are facing the Sun during the day, the Sun “blocks out” the incoming light from distant stars. As Earth moves around our Sun during the year, the Sun blocks different parts of the celestial heavens from our vision. This is why the observable zodiac constellations in our night sky change throughout the year, repeating the cycle each year.

Reinforce the difference between the apparent annual movement of the constellations in the night sky and their nightly progression, as presented in Zodiac Track. Each night the stars and constellations will “travel across the sky” because of Earth’s rotation. However, the time of year — and therefore the position of Earth in its revolution around our Sun — will determine which constellations are visible and where you will see them.

Connections to the National Science Standard(s)

Standard A, B & D (grades K–4): Understand and communicate that objects in the sky, such as stars, have patterns of movement on a nightly and yearly scale, caused by Earth’s rotation and orbit. The position of objects in the sky can be described by locating them relative to another object or the background. 

Standard A & D (grades 5–8):Understand and explain that the objects in our solar system are in regular and predictable motion. Apparent movement of the stars in the night sky is due to Earth’s own rotation on its axis and its orbit around the Sun.