Redshifted Galaxies

Definition

Redshifted galaxies refer to the phenomenon where the light emitted from distant galaxies is observed to have a longer wavelength, or a 'redshift,' compared to the light emitted from the same type of object in a laboratory on Earth. This redshift is a result of the expansion of the universe and the Doppler effect, which causes the light from receding galaxies to be shifted towards the red end of the electromagnetic spectrum.

5 Must Know Facts For Your Next Test

1. Redshifted galaxies provide evidence for the expansion of the universe, as predicted by the Big Bang theory.
2. The amount of redshift observed in a galaxy's light is directly proportional to its distance from the observer, as described by Hubble's law.
3. Redshifted galaxies are used to measure the Hubble constant, which describes the rate of expansion of the universe.
4. Studying the redshift of distant galaxies allows astronomers to determine their recession velocity and measure the overall expansion of the universe.
5. The cosmic microwave background radiation, which is the oldest light in the universe, is also redshifted due to the expansion of the universe since the time of its emission.

Review Questions

• Explain how the Doppler effect is responsible for the redshift observed in distant galaxies.
  • The Doppler effect is the change in the observed frequency or wavelength of a wave due to the relative motion between the source and the observer. In the case of redshifted galaxies, the galaxies are receding from the observer, which causes the light emitted from them to be shifted towards longer, red wavelengths. This redshift is a direct consequence of the expansion of the universe and the Doppler effect, which allows astronomers to measure the recession velocity and distance of these distant galaxies.
• Describe how the study of redshifted galaxies has provided evidence for the Big Bang theory and the expansion of the universe.
  • The observation of redshifted galaxies is a key piece of evidence supporting the Big Bang theory, which posits that the universe began in a highly dense and hot state and has been expanding ever since. The redshift of distant galaxies, as described by Hubble's law, directly demonstrates that the universe is expanding, with the rate of expansion being described by the Hubble constant. This expansion of the universe is a fundamental prediction of the Big Bang theory, and the study of redshifted galaxies has allowed astronomers to measure and confirm this expansion, providing strong support for the overall model of the universe's evolution.
• Analyze the relationship between the redshift of distant galaxies, the cosmic microwave background radiation, and the early history and evolution of the universe.
  • The redshift of distant galaxies, the cosmic microwave background radiation, and the early history and evolution of the universe are all intimately connected. The redshift of galaxies provides evidence for the expansion of the universe, as predicted by the Big Bang theory. The cosmic microwave background radiation, which is the oldest light in the universe, is also redshifted due to the expansion of the universe since the time of its emission, shortly after the Big Bang. By studying the properties of the cosmic microwave background, such as its temperature fluctuations, astronomers have been able to gain invaluable insights into the early universe, including the formation of the first structures and the evolution of the universe's large-scale structure. The consistent observations of redshifted galaxies and the cosmic microwave background radiation have allowed scientists to piece together a detailed understanding of the universe's history, from its earliest moments to its current state of expansion and evolution.

Related terms

Doppler Effect:

The Doppler effect is the change in the observed frequency or wavelength of a wave due to the relative motion between the source and the observer. In the case of redshifted galaxies, the Doppler effect causes the light from receding galaxies to be shifted towards longer, red wavelengths.

Hubble's Law: Hubble's law is the observation that the distance to a galaxy is proportional to its redshift, which is a consequence of the expansion of the universe. The rate of this expansion is known as the Hubble constant.

Cosmic Microwave Background Radiation: The cosmic microwave background radiation is the oldest light in the universe, dating back to the time of recombination, when the universe became transparent to radiation. This radiation is also redshifted due to the expansion of the universe, and its study has provided important insights into the early history and evolution of the universe.