How Astronomers Know — Evidence Lab
Reading a Star Spectrum
- Estimated time
- ~20 min
Saved locally on this device
Learning goals
- Each element absorbs specific colors of light. By matching the dark lines in a star's spectrum to lab measurements, we can tell what the star is made of — without ever visiting it.
- MS-ESS1-2 — Students relate orbital motion to gravity and distance.
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
You look at a star's spectrum and find dark lines at 656 nm (red) and 486 nm (blue-green). Match each wavelength with the element it comes from.
Hydrogen produces characteristic dark lines called the Balmer series. Two of them are at 656 nm and 486 nm.
- 656 nm (red)
- 486 nm (blue-green)
Sources
- Spectra — NASA Imagine the Universe — NASA · NASA Goddard Space Flight Center · Accessed 2026-09-01