How Astronomers Know — Evidence Lab
Stellar Spectra and Chemical Composition
- Estimated time
- ~30 min
Saved locally on this device
Learning goals
- Every element has a unique absorption-line fingerprint. Matching those fingerprints to spectra from distant stars is one of the most powerful tools in astronomy.
- HS-ESS1-3 — Students connect stages of stellar life cycles to the production of specific elements.
Help & glossary
- Use the hint ladder before checking your answer — hints get more specific.
- Incorrect answers can be retried. Feedback explains why.
- Constructed responses (CER) are self-checked — nothing is sent to a server.
Question 1 of 2
Match each strong absorption wavelength observed in a stellar spectrum with the element responsible for it.
Elements absorb specific wavelengths. Classic examples: hydrogen Balmer lines around 656/486 nm, the sodium doublet at ~589 nm, and calcium H & K lines at 393 and 397 nm.
- 656.3 nm
- 589.0 nm
- 486.1 nm
- 393.4 nm
Sources
- Spectra — NASA Imagine the Universe — NASA · NASA Goddard Space Flight Center · Accessed 2026-09-01
- Atomic Spectra Database — NIST — NIST · National Institute of Standards and Technology · Accessed 2026-09-01