Answer to Question 1
irregular
Answer to Question 2
Spectrographs are instruments that analyze light in detail by using prisms or a grating to spread light out according to wavelength to form a spectrum, revealing hundreds of spectral lines produced by atoms and molecules in the object being studied. A comparison spectrum, which contains lines of known wavelengths, allows astronomers to measure the precise wavelengths of individual spectral lines produced by an astronomical object.
Because scientists understand the details of how light interacts with matter, a spectrum carries a tremendous amount of information.