Spectra

Definition

Spectra are the range of wavelengths or frequencies of electromagnetic radiation emitted or absorbed by an object. They provide crucial information about the physical properties and composition of astronomical objects.

5 Must Know Facts For Your Next Test

1. There are three types of spectra: continuous, emission, and absorption.
2. Continuous spectra are produced by hot, dense objects like stars or incandescent bulbs.
3. Emission spectra appear as bright lines on a dark background and are produced by hot, low-density gases.
4. Absorption spectra show dark lines on a continuous spectrum and occur when a cooler gas absorbs specific wavelengths from a hotter light source behind it.
5. The study of spectra allows astronomers to determine the chemical composition, temperature, density, mass, distance, luminosity, and relative motion of celestial objects.

Review Questions

• What are the three main types of spectra?
• How do emission and absorption spectra differ?
• Why is the analysis of spectra important in astronomy?

Related terms

Electromagnetic Spectrum:

The range of all types of electromagnetic radiation from radio waves to gamma rays.

Doppler Effect:

A change in wavelength due to the relative motion between the source and observer.

Photometer:

An instrument used to measure the intensity of light from an astronomical object.