The student investigates basic properties of spectra in the lab using emission tubes and spectroscopes. Background and Theory Astronomy is nearly entirely a study of light. From this single source of information, we can often find the physical conditions, compositions and processes in distant objects. This type of emission is caused by a opaque material which emits radiation because of its temperature.
Hotter objects are brighter and bluer than cooler objects.
All objects have continuum radiation. An absorption line is characterized by a lack of radiation at specific wavelength. Absorption lines are created by viewing a hot opaque object through a cooler, thin gas. The cool gas in front absorbs some of the continuum emission from the background source, and re-emits it in another direction, or at another frequency. Absorption lines are subtracted from the continuum emission, so that they appear fainter.