Why are things blue shifted and not violet shifted?

  • Thread starter Entropee
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In summary, objects moving towards us are labeled as blue shifted, but this does not necessarily mean they are physically blue. This label is used to denote a shift in frequency. Acceleration of an object in relation to us can alter its wavelength. Additionally, violet and purple are not the same color, with violet being a spectral color and purple being a perceptual color. Entropee did not mention anything about acceleration altering wavelength.
  • #1
Entropee
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If objects are moving away from us, they are known as red shifted, so why are objects moving towards us blue shifted and not violet shifted?
 
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  • #2
Semantics. Blue-shifted objects are not necessarily blue: an object emitting at 5 um moving towards us is still blue shifted even though it is way outside the visible spectrum.
 
  • #3
Entropee said:
If objects are moving away from us, they are known as red shifted, so why are objects moving towards us blue shifted and not violet shifted?

"blue" and "red" are just labels used to denote upshift or downshift in frequency.
 
  • #4
Oh ok, yeah I just thought it was odd since most elemtary school students even know that purple comes after blue using roygbiv. Thanks :]
 
  • #5
Entropee said:
If objects are moving away from us, they are known as red shifted, so why are objects moving towards us blue shifted and not violet shifted?

I didn't know that.

So acceleration of the object in relation to us alter wave length?

:eek:
 
  • #6
Impagliazzo said:
I didn't know that.

So acceleration of the object in relation to us alter wave length?

:eek:

What? Entropee said nothing of the kind.
 
  • #7
Entropee said:
Oh ok, yeah I just thought it was odd since most elemtary school students even know that purple comes after blue using roygbiv. Thanks :]
Actually, purple is not the same as violet. Violet is a spectral color consisting of wavelengths shorter than blue, but purple is a perceptual color seen only when both blue and red wavelengths are present.
 
  • #8
Oh lol, my bad, I guess it's time for me to go back to Elementary school?
 
  • #9
ideasrule said:
What? Entropee said nothing of the kind.

But what he said is right?

I want to know why!

Edit: Ok so I guess I just got pretty inventive with lack of clear information. LOL
 
Last edited:

1. Why do objects appear blue shifted?

Objects appear blue shifted because of the Doppler effect, which is the apparent change in frequency and wavelength of a wave when the source and observer are in relative motion. When an object is moving towards an observer, the wavelength of light is compressed, making it appear to have a higher frequency and therefore a bluer color.

2. How is blue shift different from red shift?

Blue shift and red shift are opposite effects of the Doppler effect. Blue shift occurs when an object is moving towards an observer and the wavelength of light appears to be compressed, while red shift occurs when an object is moving away from an observer and the wavelength of light appears to be stretched.

3. What causes the Doppler effect?

The Doppler effect is caused by the relative motion between the source of a wave and the observer. This can occur with any type of wave, including light, sound, and water waves.

4. Why are some objects blue shifted while others are red shifted?

The amount of blue or red shift an object exhibits depends on the speed and direction of its motion relative to the observer. Objects moving towards the observer will appear blue shifted, while those moving away will appear red shifted. The amount of shift also depends on the speed of the object relative to the speed of light.

5. How is blue shifting used in science?

Blue shifting is used in many areas of science, including astronomy, cosmology, and meteorology. In astronomy, scientists can use blue shifting to determine the speed and direction of objects in space, such as stars and galaxies. In meteorology, blue shifting can be used to track the movement of storms and analyze wind patterns. Blue shifting is also used in medical imaging, such as Doppler ultrasound, to measure the flow of blood and other fluids in the body.

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