Electromagnetic radiation, including light, comes in a wide range of wavelengths and is used by astronomers to study astronomical objects. Radio waves have the longest wavelengths while gamma rays have the shortest. Astronomers use spectroscopes to separate starlight into colors and study spectra, allowing them to determine properties of stars like their composition, temperature, and luminosity. Looking at objects across different wavelengths provides additional information.

1. The Electromagnetic Radiation (Light – the Supreme Informant!)

2. The Electromagnetic SpectrumMore than meets the eye!

3. Examples from Space!

4. WavelengthThe distance from one wave crest to the nextRadio waves have longest wavelength and Gamma rays have shortest!

5. Wavelength UnitsMeters (like on last slide and in book, p. 613)More commonly in nanometers (1 nm = 10-9meters)Angstroms still usedNamed for Swedish Astronomer who first named these wavelengths1 nanometer = 10 Ao

6. How light or electromagnetic radiation is used in AstronomyAstronomers use a tool called a spectroscope to separate starlight into its colors – in this way, they can tell what a star is made of, its temperature, luminosity and so on…Astronomers can look at astronomical objects at different wavelengths…

7. Spectra of a Star