Answering Questions about Galaxies, Part I
The two pictures below are of two different types of galaxies.
Spiral Galaxy
Elliptical Galaxy
In the space below, write down everything you notice about how the spiral galaxy and the elliptical
galaxy look.
Characteristics of a Spiral Galaxy
Characteristics of an Elliptical Galaxy
Your job as an astronomer is very simple. You need to figure out which of the galaxies below are spiral
galaxies and which are elliptical galaxies. Just look out for the things that make spiral and elliptical
galaxies different. Use the previous page for reference!
For each picture below, write down (in the box) whether you think the galaxy is a spiral or an elliptical.
Some galaxies are a bit more tricky. As you noticed in the pictures on the previous page, some spiral
galaxies can look like elliptical galaxies when viewed from the side. These are called “edge-on spirals.”
Spirals that you see from the top, where the spiral arms are clear, are called “face-on spirals.”
See if you can tell which of the trickier galaxies below are spirals and which are ellipticals. Write your
answers in the boxes below each picture.
Most galaxies are billions of light-years away and look very dim to our telescopes. See if you can tell
whether these faint galaxies are spirals or ellipticals. Write your answers down in the boxes!
Answering Questions about Galaxies, Part II
1. Think about the question, “What type of galaxy is most common?”
If someone at your table said, “Most galaxies are elliptical,” would you agree or disagree based
on the galaxies you have looked at so far?
Go back and count the the galaxies you put into spiral and elliptical categories. How many of
each are there? Do those numbers mean that most galaxies are elliptical? Explain.
2. Someone shows you the data table below and asks you the question, “What type of galaxy is
most common?”
Spiral Galaxies
Elliptical Galaxies
50
150
Pretend that you just had this person’s numbers, and not your own. If you just use the numbers in
this table, what is your answer to the question? Provide evidence from the table.
3. Imagine that your team has been asked to design an observation plan about galaxies. Describe
what evidence you would need to collect to answer the question, “What fraction of galaxies
observed are elliptical, and what fraction are spiral?”
Write step-by-step instructions for the evidence that you need and an explanation of how to get it.
The goal is to be detailed enough that someone else could repeat what you did!
Answering Questions about Galaxies, Part III
You now have your own set of galaxies. You can use these to answer one of the questions we
wrote on the board.
It’s your turn to come up with both a way to collect data and an answer to the question, based on
the data you collected.
This is the same process you’ll follow to do your science fair project, but on a different topic.
With your group, fill out the research report below for the question you choose.
Research Report
Specific research question:
Step-by-step procedure, with sketches if needed, to collect evidence:
Data table:
Evidence-based conclusion:
Answering Your Own Question
Once you have an idea of what you would like to investigate, you can make a plan just like we
did with the galaxies:
Research Report
What is your specific research question?
What is your step-by-step procedure to collect evidence? Fill out the checklist on the “Tips for
Taking Data” page.
What materials will you need to research your question?