Why are absorption spectra important in astronomy?

Absorption spectra are crucial in astronomy primarily because they provide valuable information about the composition of astronomical bodies. When light from a star or other celestial object passes through a cooler gas or dust cloud, specific wavelengths of light are absorbed, resulting in dark lines appearing in the spectrum. These absorption lines correspond to particular elements and compounds, allowing astronomers to identify the chemical composition of stars, galaxies, and nebulae.

By analyzing these absorption lines, astronomers can ascertain not only which elements are present but also their abundance and temperature. This information can lead to a deeper understanding of stellar processes, evolutionary stages, and even the physical conditions of distant objects. The ability to decode the elements in a star's atmosphere can provide insights into its age, mass, and the processes occurring within it.

In contrast, the other options focus on aspects that absorption spectra do not directly address; for instance, they do not measure distances, provide images, or predict movements. Understanding the composition of celestial bodies is foundational for establishing a broader context in astrophysics and cosmology.