The Electromagnetic Spectrum and the Doppler Effect

Each color on the electromagnetic spectrum has a different wavelength.

Light from every star travels through space and time to reach the Earth. This light is the basis of modern astronomy. It allows astronomers to calculate a star's distance from Earth and its temperature. Believe it or not, not all stars are white and not all light is visible. Light and its waves are an important focus of study for astronomers.

You may already know that stars and other celestial objects move in space. Using their light, astronomers can actually tell whether or not they are approaching the Earth or moving away from it, and at what speed they are doing so. Astronomers take advantage of a phenomenon known as the Doppler Effect of waves to make such calculations. It is another way that stars and other faraway objects can be studied from positions on Earth.

Essential Questions

• What is the nature of electromagnetic radiation?
• What is the Doppler effect and how does it apply to astronomy?
• What is the difference between redshift and blueshift?