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. An emission line is characterized by excessive radiation at specific wavelengths.