Student activity · Grades 9–12 · about 15 minutes
Stellar Parallax Worksheet
Goal: Use parallax angles to measure distances to nearby stars, and explain why the method gets harder for distant stars.
What to do
- Press the “Proxima Centauri” preset and record the distance and light travel time.
- Press “Ten parsecs” and “One kiloparsec” and record the readouts.
- Type 0.379 into Parallax angle (the parallax of Sirius) and record the readouts. Then try 0.05.
Record your results
| Setting | Distance | Light travel |
|---|---|---|
| Proxima Centauri (0.768″) | ||
| Ten parsecs (0.1″) | ||
| One kiloparsec (0.001″) | ||
| Sirius (0.379″) | ||
| Parallax 0.05″ |
Questions
How far away is Proxima Centauri in parsecs and in light-years?
Compare the “Ten parsecs” and “One kiloparsec” rows. The angle became 100 times smaller. What happened to the distance? Write the rule.
Predict: how far away is a star with a parallax of 0.05″? Check with the lab.
Sirius has a parallax of 0.379″. How far away is it in light-years?
Why are distant stars harder to measure with parallax?
Explain where the parallax shift comes from. Add a quick sketch if it helps.
Free from The Astronomy Lab · theastronomylab.com