What is spectroscopy used for in astronomy?

Spectroscopy is a crucial tool in astronomy that allows scientists to analyze the light emitted, absorbed, or scattered by objects in space, such as stars and galaxies. When light interacts with matter, it can produce a spectrum—a unique fingerprint of colors that represent various wavelengths of light. By examining this spectrum, astronomers can determine several important properties of celestial bodies.

For example, spectroscopy enables the identification of chemical compositions, temperatures, densities, masses, distances, luminosities, and relative motions of astronomical objects. Each element and molecule absorbs and emits light at characteristic wavelengths, so analyzing the spectrum can reveal what elements are present in a star or galaxy and provide information about physical conditions, such as temperature and pressure.

In contrast, other options focus on different aspects. Measuring the distance of stars typically involves methods like parallax or standard candles, tracking asteroid movements involves observing their positions over time, and determining the mass of celestial bodies often requires gravitational calculations based on their effects on nearby objects. Each of these methods serves a specific purpose, but spectroscopy uniquely provides insights into the nature of light and matter in the universe.