Spectra: What Stars Are Made Of: Practice Problem Solutions

1. A continuous spectrum, a smooth rainbow of colors.

2. Cooler gas in the star's atmosphere absorbs light at certain colors from the hotter light coming from below, leaving dark lines.

3. Each element's electrons can only absorb or emit light at certain energies, which depends on the atom's structure.

4. A new yellow line in the Sun's spectrum in 1868 did not match any known element; it was named helium after helios, the Greek word for the Sun. It was later found on Earth.

5. The differences come mainly from temperature, not composition. Most stars are about 75% hydrogen and 25% helium.

6. Class G, about 5,800 K.

7. Any two of: speed toward or away from us (Doppler), spin, the atmosphere of a planet in front of it, and magnetic fields.