Introduction: 3D Constellation in a Box
To learn about the major stars in constellations students will complete a two-part project. The first part will be to conduct research using free online software to establish a database of the major stars in a chosen constellation. In the second part, students will draw a map of the constellation, then use the coordinates of the stars to create an accurate three dimensional model in a box. They will then see how the stars shift to different positions as they change their viewpoint away from Earth. This lesson should take about five class periods of 90 minutes each, or about 7.5 total hours.
6-10 grades in middle school through lower division Earth Science classes. For higher division astronomy students, try my lesson plan titled Discovering Our Stellar Neighborhood: Modeling the Nearby Stars in Three Dimensions in the Summer 2014 edition of The Science Teacher, Pp. 31-37.
Students should have an understanding of the differences between stars and planets and the ability to work with proportions and ratios.
NGSS: This lesson helps to fulfill the following Next Generation Science Standards:
Disciplinary Core Ideas for Earth and Space Science and Physical Science
MS-ESS1 and HS-ESS1: Earth’s Place in the Universe ESS1.A – The Universe and Its Stars Patterns of the apparent motion of the sun, the moon, and stars in the sky can be observed, described, predicted, and explained with models (MS-ESS1-1)
MS-PS2-2: Motion and Stability: Forces and Interactions
Scientific and Engineering Practices: Developing and Using Models (MS-ESS1-2) Analyzing and Interpreting Data (MS-ESS1-3)
Scale, Proportion, and Quantity
Time, space, energy: Phenomena observed at various scales using models to study systems that are too large or too small (MS-ESS1-3 and MS-ESS1-4)
Systems and System Models: Models can be used to represent systems and their interactions (MS-ESS1-2)
Stability and Change
• One cardboard box for each group (ideally the type of box that copy paper comes in or a banker’s box)
• Large sheets of paper (same size as the interior bottom of the box)
• Fin tip colored markers
• Metric rulers
• Masking tape
• Drawing compasses with sharp points
• Canning jar lids (small) – one for each group
• Thin black string or strong embroidery thread, single strand – large spool
• Colored beads: one package each of red, orange, yellow, pale yellow, white, light blue, and purple or lavender.
• Graph paper sheet for each group
• A computer for each group with Stellarium software installed (this is an open-source free program available from SourceForge at: https://sourceforge.net/projects/stellarium/)
By the end of this lesson, students will be able to:
1. identify the major stars in chosen constellations including the meaning of their names, their spectral types, and their coordinates;
2. build an accurate scale model of their constellation showing the major stars in their correct positions (distances, right ascension, and declination) and spectral types (OBAFGKM);
3. determine how the constellations will distort as the observer travels different distances in different directions due to the apparent parallax of nearby stars; and
4. identify the distortion of constellations over large time periods due to the proper motions of the stars and our sun.
Before this lesson begins, the teacher will need to become familiar with Stellarium software, especially how to change the settings to turn on the constellation boarders and asterism lines, to turn off the ground and sky, and to turn up the visibility of stars.
Step 1: Day 1: the Stars and Constellations
Ask the students if they know the names of any constellations or stars. Develop a list on the board under each heading and answer questions. If they have trouble listing constellations, ask them to list their zodiac signs. Explain that the zodiac constellations are the ones located along the sun’s apparent path through the sky, but that they really represent the ecliptic constellations, or the plane of the solar system. You can supply some stars or constellations if they are unfamiliar, such as Betelgeuse, Sirius, Bellatrix, Regulus, or Alpha Centauri for stars and Orion, Draco, and Scorpio for constellations. Explain that some of the constellations listed, such as the Big Dipper, are actually asterisms, or patterns of stars, whereas constellations are areas of the sky. Some asterisms, such as the Summer Triangle, cross over several constellations. The Big Dipper is an asterism contained inside the constellation of Ursa Majoris. Explain that modern astronomers recognize 88 constellations, some larger than others. Point out that the Black family in the Harry Potter series are named after stars and constellations.
Step 2: II. Using Stellarium
Explain the project they will be working on – to build a scale model of a constellation inside a box. To do this, they need to pick and become familiar with a constellation. They can use a free program called Stellarium that acts like a planetarium on a computer. Explain the procedure/requirements and divide the students up into pre-chosen teams. Have each team choose a different constellation. If they choose an obscure constellation without any prominent stars (such as Cancer or Ares) you can suggest more prominent constellations.
Requirements: The student teams will use Stellarium and the Internet to look up information and prominent stars on their chosen constellation. They will fill out the Star Data Table form, with information on the meaning or mythology behind the constellation and a list of the seven most prominent stars along with their proper name (if any) and the name’s meaning (they will need to look this up. A good website for understanding star name and number systems is: https://www.skyandtelescope.com/astronomy-resources/names-of-the-stars/. A good list for the meanings of Arabic and Greek proper star names along with their Bayer designations is: https://www.naic.edu/~gibson/starnames/ starnames.html. They also need to use Stellarium to zoom in on their constellation and click on the brightest stars. This will bring up a list of data on that star, including alternative names or numbers and the coordinates of the star (Right Ascension, or celestial longitude, Declination, or celestial latitude, and light years distance. Students also need to right down the star’s spectral class using the OBAFGKM classifications. Optionally, advanced students can write down the star’s apparent and absolute magnitudes.
This research will take all of the first day of this lesson and depending on the age of the students and the length of your classes, may take part of a second day.
Step 3: Days Two and Three: Constructing the Constellation Box
I. Drawing the Star Map:
Provide each team with a box to use for their constellation model. If you have a free standing projector then the ideal way for students to draw their constellation map is to use the bottom of the box to trace an outline on a large sheet of paper, then cut it out slightly smaller so the paper will fit snuggly into the bottom of the box without wrinkling or leaving too much extra space. With the paper cut, tape it to a wall and move the projector so that it shines directly on the paper and fills it up without overlapping the edges.
Train the students how to use Stellarium, especially how to search for constellations and zoom in, how to go into the settings and turn up the apparent magnitude of stars, turn off the sky, fog, and ground, and turn on the constellation markers such as the asterism lines and constellation art.
Zoom in to the each team’s constellation and turn on the constellation marking lines. Then have the students use a pencil to lightly trace out the lines and draw circles around the stars where the lines intersect or cross over the stars. Have the students use colored markers to fill in the appropriate colors for the stars: Type O is light blue or lavender, Type B is blue, type A is left white, Type F is light yellow, Type G is bright yellow, Type K is orange, and Type M is red. Use a black or gray pen to draw in the asterism lines. The students should also label each star and write down its spectral type and light years distance. They then need to create a nice title text for the name of the constellation. Finally, they should measure off every five centimeters along the edges of their map and draw a grid of horizontal and vertical lines in pencil.
Once the constellation map is complete, tape it to the bottom of the box using masking tape.
Step 4: II. Creating the Eyepiece:
To provide an eyepiece of sorts, use a small canning jar lid and tie it in place hanging in the opening at the front of the box, securing it with the black string to the top and both sides of the box to prevent the eyepiece from swaying or moving. Keep the eyepiece as close to the front of the box as possible while still keeping it secure.
Step 5: III. Hanging the Stars:
Once the students have the box set up, they will need to get enough of the correct color of beads to match the seven stars they will hang in their model. Advanced students can use beads of different sizes as well as colors to represent the comparative sizes of the stars, with red giants such as Betelgeuse being the largest and red dwarfs the smallest (although Stellarium will not list red dwarfs, unless advanced students want to look them up and their coordinates separately and add them to the model. They could also look up known brown dwarfs and use small brown beads for them).
They will need to cut lengths of string that are as long as their box and tie these lengths to their beads. Monofilament string of moderate thickness is best.
While a student is making the beads, others can begin to measure the locations of the stars in three-dimensional space. Students must create a proportion/scale ratio with which to measure the distance to stars in the model. This is done by finding the star in their Star Table with the greatest light years distance and using that to create the scale. For example, in the constellation Orion, of the major stars Alnilam (the center star in Orion’s Belt) has the greatest distance at 1342 light years. Have the students measure the depth of the box from the knot where the eyepiece hangs to the bottom of the box (about 23 cm in most boxes). Calculate the scale by dividing the greatest star distance by the size of the box, which in this case would be about 58.3 light years per centimeter. Rounding up is a good idea to provide a little space between the farthest star and the bottom of the box, so the scale we will use for Orion is 60 light years per centimeter. To find the distances to hang each star, take the star’s light years distance and divide it by the scale number. So Betelgeuse, with a distance of 427 light years, will be 7.1 cm from the eyepiece knot.
To hang the stars, look through the center of the eyepiece to the star you want to hang and visualize a line going vertically up from that star to the top of the box. Make a small mark on the top side of the box next to the far wall. Then measure in a straight line from the eyepiece top knot to that mark, marking off the distance you calculated for the scale distance to the star. The poke a hole in the top side of the box with the pointed end of a drawing compass or other sharp object. Thread the loose end of the star’s string through the hole from the bottom while another student looks through the center of the eyepiece. When the star’s bead lines up with the star on the map, take a piece of masking tape and securely tape down the string on the top side of the box. You may want to use two pieces of tape in a cross shape.
Repeat this process for the other stars until all seven are hung. It this is down correctly, the stars should line up with the background constellation map just as we would see them from Earth if you look through the center of the eyepiece.
Step 6: Day Four: Traveling Through Space
I. Charting Constellation Distortions
The constellations are merely the positions of the stars as we see them from Earth, but as our Sun travels through space, or ifwe could travel through space, we would see the constellations distort as the closer stars appeared to move more than the distant stars.
To lead into this discussion, ask the students to visualize themselves riding in a car down a freeway with billboards next to the road and distant mountains in the background several miles away. As they travel, the nearby objects (billboards) appear to move backward at a rapid rate but the distant mountains hardly seem to move at all except over long periods of time. This isn’t because either the billboards or the mountains are moving but because we are. This is called parallax, and this concept can actually be used to measure the distances to stars. As the Earth orbits around the Sun each year, the nearby stars will seem to wiggle back and forth against the backdrop of the distant stars. By measuring the angle of this parallax and applying a little bit of trigonometry, the distance to the stars can be calculated. (Note: For advanced or higher division students, they could try my lesson plan on how to use parallax to measure stellar distances. It is online at the MIT BLOSSOMS project at: https://blossoms.mit.edu/videos/lessons/ parallax_activity_measuring_distances_nearby_stars )
To demonstrate this distortion of the constellation, have the students use a piece of graph paper and draw out the constellation using a black or dark pen, aligning their drawing with the grid they created on the constellation map. Then have a student look at the constellation from a viewpoint five centimeters to the right of the center of the eyepiece, drawing them on their graph paper in a different color relative to the constellation map star positions. Then have them repeat this by moving their eye eight centimeters to the left of the eyepiece’s center and five centimeters above the eyepiece’s center. Each position should be done in a different color.
Step 7: II. Final Questions:
Complete this lesson by asking the students the following questions:
1. Which stars seem to move the most – the nearby stars, or the distant stars? Why?
2. Why are the constellations that we see not really permanent? (Stars do move through space in their own directions. Over tens of thousands of years, the constellations will distort and become unrecognizable. Our Sun is also moving through space and carrying the Earth with it, so that over time we will leave our local stars behind.)
3. Using the scale the students use, have them calculate the size of our Milky Way galaxy using the same scale. The Milky Way is approximately 100,000 light years in diameter, so at the scale we used for Orion, our galaxy would be 1666.7 cm across, or 16.7 meters and would contain around 200-300 billion stars. Student answers will vary depending on the scale of their models.
Step 8: Further Lessons/Extensions:
This lesson is designed for 6th grade students up to about tenth grade but can be modified and extended for higher division or advanced students. One follow-up would be to teach students the parallax lesson linked above to learn more about measuring stellar distances. Advanced students could add more to their Star Tables, such as including Deep Sky Objects such as galaxies and nebulas using the Messier and NGC catalogs. These could be added to their maps before taping them into the box.
Another extension is to teach students about the Hertzsprung-Russell diagram and how it is central to our understanding of the stars and their sizes, temperatures, formation, and evolution.
Step 9: Differentiation:
For English Language Learners and to provide a global aware- ness option to the lesson, have students find the mythology of constellations from multiple cultures other than Greco=Roman names/patterns. For students with accommodations or learnng disabilities, you can provide a pre-made constellation box and focus on the use of Stellarium to create a Data Table on the stars, but without the coordinates. Have them find the other data: star names and meanings, alternate names, and color/stellar types.
Step 10: Evaluation:
Depending on the different extensions you teach, your evaluation rubric will need to contain the following:
A – The quality of the student constellation boxes, including aesthetics (neatness, artistry), accuracy, and thoroughness.
B – Thoroughness of their Star Data Table, to include stellar types, coordinates, names and their meanings, alternative names, and constellation mythology.
C – The accuracy of their graphs showing the parallax of the stars as the observer moves away from Earth’s position.
D – The thoroughness, insight, and depth shown by their answers to the final questions.
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