The Doppler Effect: Near and Far Galaxies

[jerome951000]

I found a question in a Maltese physics past paper dealing with the doppler effect. I managed to figure out the part dealing with the effect of motion of the wave source, but i was asked this:

How does The Doppler Effect show us the difference between galaxies that are near and those that are far away?

I was familiar with the doppler effect and the motion of the source causing it, but i never knew that the distance could make a difference. Any help would be much appreciated.

 

[jtbell]

Try a Google search on "Hubble expansion".

 

[jerome951000]

thanks that was really helpful. it said that the redshift acquired value of the velocity of the receding galaxies is proportional to their distance from earth. thanks again :-)

 

[jerome951000]

how are the distances between the Earth and other galaxies deciphered using the redshift acquired velocity since these two are proportional?

 

[PJC01]

The Doppler Effect is a well-known phenomenon in physics that describes the change in frequency of a wave as it moves towards or away from an observer. This effect is commonly observed in everyday life, such as the change in pitch of a siren as an ambulance passes by. However, it also has important applications in astronomy, specifically in determining the distance of galaxies.

When we observe light from distant galaxies, we are essentially observing waves of electromagnetic radiation. These waves are emitted from the galaxy and travel through space towards us. As the galaxy moves towards or away from us, the wavelength of the emitted light changes due to the Doppler Effect. This means that the frequency of the light also changes, resulting in a shift towards the blue or red end of the electromagnetic spectrum.

By measuring this shift in the wavelength of light from a galaxy, we can determine its velocity and direction of motion relative to us. This is known as the redshift or blueshift, depending on whether the galaxy is moving away or towards us. The greater the shift, the faster the galaxy is moving away from us.

Now, the distance of a galaxy can also affect this shift. The farther away a galaxy is, the faster it is moving away from us due to the expansion of the universe. This results in a larger redshift, indicating a greater distance. On the other hand, galaxies that are closer to us have a smaller redshift, indicating a shorter distance.

In summary, the Doppler Effect allows us to distinguish between galaxies that are near and far away by measuring the shift in the wavelength of light emitted from them. This is an important tool in astronomy for understanding the motion and distance of galaxies, and ultimately, the structure and evolution of our universe. I hope this explanation helps to clarify the role of the Doppler Effect in studying the vastness of our universe.