Most of what is known about stars comes from spectral studies. There are 3 kinds of visible spectra: Continuous, bright-line and dark-line. Continuous – unbroken band of colors from a source sending out all visible wavelengths.

Continuous spectra can come from a (hot) glowing solid, a glowing liquid or a glowing gas (star). Bright-line spectrum – also called an emission spectrum, is a series of unevenly spaced lines of different colors and brightness. Hydrogen emission spectrum

Every element has its own unique bright-line spectrum, like a fingerprint. Helium emission spectrum Dark-line spectrum – a continuous spectrum with dark lines where light has been absorbed. (absorption spectrum) Helium absorption spectrum

The dark lines are in the exact same place as the bright lines would be for the same element in a bright-line spectrum. The dark lines are formed when light passes through a cooler gas. The dark lines tell us what gases are in the atmospheres of stars and planets.

Stars’ (dark-line) spectra. Dark-line spectrum Bright-line spectrum Hydrogen emission spectrum Stars’ (dark-line) spectra. Blueshift Redshift

The student will understand the similarities and differences between the three types of spectra. In addition, students will understand how spectra are used to learn about planets and stars. Materials - Low pressure gas discharge tubes, high voltage electrical exciter and spectroscopes.

What is a continuous spectrum? What is a bright line spectrum? What is a dark line spectrum? What does the bumper sticker mean? If the background on this bumper-sticker appears blue, you’re going way too fast!