Pictures in the Sky

“Pictures in the Sky”

Teacher Background

What are the stars? That's a question that humans must have asked almost as soon as consciousness emerged. Go out alone, or even better with a child, to a place with clear night skies unpolluted by city lights and look up Almost certainly you too will wonder. One of the earliest ideas must have been that stars were campfires in the sky, like those the ancients sat around each night. Like distant campfires the heavenly lights flickered. What kind of beings might sit around those distant campfires? Another tribe? Beloved ancestors, looking down to help care for those who followed? Other cultures believed the sky was a crystal sphere. At night, there were holes through which the fires of Hades could be seen, reminding people to behave well! Occasionally a spark came through the hole, creating a shooting star! Almost all cultures looked up and saw pictures in the sky, placing there the gods and goddesses who were important to them, or familiar objects from daily life whose lines somewhat coincided with the patterns made by the brightest stars up above. But those forms are not, of course, really there. They’re a projection from Earth up into the stars, a cosmic Rorschach test.

This Activity uses a randomly-generated set of points corresponding to imaginary bright stars, and invites students to invent new constellations. It also provides an extension activity by which the two dimensional “pictures in the sky” are broken down into the actual 3-dimensional grouping of stars. Behind the familiar constellations, students encounter the actual spacing of seemingly associated stars across many light years.

Objectives

Students will plot numbers on the X and Y coordinates of a graph.
Students will construct “new constellations” based on random associations of points seen on the graph, and thereby understand the arbitrary character of traditional constellations.
Students will deconstruct the 2-D pattern of traditional constellations into 3-D models which accurately represent the component stars true distances from Earth in light years.
Students will create in words or image the “story” of their new constellation.

Materials

old telephone book pages, cut into strips: you only need the section of the page with the actual

numbers, not the names (to minimize any incentive for prank calls!)

graph paper

pencil

crayons, markers, etc.

ruler

Vocabulary

constellation, light year, two-dimensional, three-dimensional, astrology, astronomy

Engage

Ask students what constellations they know. Write answers on the board. If you have students from various nations in your class, solicit some constellations unfamiliar to native-born students. See if you’ve got some variant descriptions of the same stars. Then focus on one set of stars with nice cross-cultural variations. For example, everyone in North America knows “The Big Dipper”, that distinctive pattern made up by seven stars in the night sky. It's a group of stars called a constellation, Latin for “con” (together) and “stella” (star). Why is it known as the Dipper? Native Americans believed that it held rain water. When the Dipper was in a certain position in the sky water fell from it! The farm folk of olde England saw a Plow instead of a dipper. The Chinese saw a Celestial Bureaucrat seated on a cloud traveling on his rounds about the North Star. Which picture and associated story is correct? In reality, none of them or all of them! The Big Dipper, Orion the Hunter, Cancer the Crab, the constellations made familiar through the pseudo-science of astrology, and all the other constellations were invented by humans to answer the question of why the stars were up there, and to make sense of their connection to us down here on Earth. (See Carl Sagan’s Cosmos, chapter 3, for more on constellations.)

In reality, stars are randomly scattered across the sky as seen from Earth. Those pictures exist only in our minds. This Activity lets students understand that, but also shows that it can be fun to let your imagination run wild across the heavens!

Procedure

Have each student draw an X and a Y axis on a sheet of graph paper. Number each axis from 0 to 100. (Note: the numbering scale on the axis can vary based on the size of the grid. Some students may go by two's or four's, or five's).

Label the X axis "First Two Numbers," and the Y axis "Second Two Numbers." Give each student a strip of telephone numbers.

Plot the first 25 telephone numbers on the graph. To do this, ignore the local exchange and only use the last four numbers. If the number is 555-2376, you will omit 555 and go across on the X axis to 23, and then go up to 76 on the Y axis and mark with a bold dot. DON’T YET START TO CONNECT THE DOTS!!!

Tell students to look at what they’ve created. “Imagine it’s a section of the night sky. What shape(s) do you see? Ignore some of the 25 ‘stars’, and use some of the others to make your new constellation.”

Provide students with some rules for making their constellations. They must use at least two stars. There’s no reason to connect all the dots. They can simply draw around the stars to create the shape. If you want more than one constellation, they must be thematically related. They can color their image to make it look convincing.

Students can write a myth describing the constellation they’ve created. It must have a title and describe what the object/character did to achieve "constellation status”. Traditional constellations told a story or memorialized a legend important to the society which dreamt them up. The heroes or goddesses did something wonderful or terrible. Their myths should similarly be about something significant to their society. How did the object get into the sky? What is the moral of their story?

Expand/Extend/Adapt

Teacher Charlie Lindgren offers a few options in making the new constellations: “If everyone uses the same set of numbers, but then makes up their own, different constellations from a sub-set of the 25 points, you can emphasize the arbitrariness of what pictures in the sky get drawn by human minds. This is really neat! It's amazing seeing the different things the kids see. Another option is for everyone to use the same grid duplicated to meet the numbers in your class. I usually do it this way. For some kids, counting by fours, fives, etc. can be too difficult. If the numbers are already there, the problem is solved!”

Suggested URLs

Has the Greek myths for the classical constellations, and star information.

http://www.astro.wisc.edu/~dolan/constellations/

Each constellation is listed with an interactive star chart, information on position in the sky, and the names of its stars.

http://windows.ivv.nasa.gov/cgi-bin/tour.cgi?link=/the_universe/Constellations/constnavi.html&sw=false&sn=1&d=/the_universe/Constellations&edu=mid&br=graphic&cd=false&tour=&fr=f

Good background information on constellations and myths.