Exploring Light Wavelengths from the Sun's Surface

In summary: However, it's really just a layer of gas. The photosphere is constantly being pushed and pulled by the sun's internal pressure and temperature. This motion creates a Doppler shift in the light that we see, and the edges of the sun rotate more quickly than the center. This difference is tiny, but it's detectable with instruments.
  • #1
mcgucken
29
0
When we look at the sun, does light emitted from the edges of the sun have a different wavelength than light emitted from the center of the disk?
 
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  • #2
I would imagine that there is a small difference. Since the sun rotates on its axis, one edge is accelerating towards us and the other away. So the biggest difference would be from edge to edge across its equator.
 
  • #3
Has anything like this been measured? Is there any experimental data regarding this? Thanks!
 
  • #4
I would tend to think it does not because all light moves through space at the speed of light but there could be a bit more light dencer perhaps at the center of the sun disk than at the edge hmm ill do some more research interesting question.

I am thinking the inverse square law would apply to measuring...
 
  • #5
mcgucken said:
When we look at the sun, does light emitted from the edges of the sun have a different wavelength than light emitted from the center of the disk?
You would be referring to the Doppler effect. It would be a simple matter to take the speed of the emitting surface and calculate the Doppler effect. One could confirm by looking at the Doppler shift of emission lines from the edge of the sun rotating toward and the edge rotating away, to which GOD__AM alluded. I don't believe the effect is significant, IIRC.

Certainly the speed of light is constant, the frequency however is influenced by the speed (velocity) of the emission source.
 
  • #6
There is a small shift favoring longer wavelengths due to limb darkening. There is also a very slight doppler shift.
 
  • #7
Fraunhoffer Lines first analysed by Fraunhoffer himself depicted different wavelengths coming from the sun.

BJ
 
  • #8
mcgucken said:
When we look at the sun, does light emitted from the edges of the sun have a different wavelength than light emitted from the center of the disk?

Yes, and the difference in wavelength (doppler shift) between the eastern to the western solar limb (at the equator) is how we can determine the amount of rotation of the solar surface...

Creator :smile:
 
  • #9
Creator said:
Yes, and the difference in wavelength (doppler shift) between the eastern to the western solar limb (at the equator) is how we can determine the amount of rotation of the solar surface...

Creator :smile:
Being just gas of increasing density, I don't really know if we can call it (the photosphere) a surface.(?) Also, since the Sun has a differential rotation of about 25 days at the equator and ~29 days at high latitudes, does anyone know (legit question) if we have instruments sensitive enough to measure the very small difference (doppler) between the approaching and receding "edges"? 25 days in a long time for one rotation... :confused:

I had always thought that we observed the rotation rate by observing sunspots and convection granules at different latitudes.
 
  • #10
Labguy said:
...does anyone know (legit question) if we have instruments sensitive enough to measure the very small difference (doppler) between the approaching and receding "edges"? 25 days in a long time for one rotation... :confused:

I had always thought that we observed the rotation rate by observing sunspots and convection granules at different latitudes.
The Michelson Doppler Imager has a resolution of about 20m/s [compared to the solar equatorial revolution speed of about 2000m/s].
http://soi.stanford.edu/science/obs_prog.html
Astrometric dopplers can resolve line of sight velocities down to about 3 m/s [!].
 
  • #11
There are gravitational effects that draw the photons emmited from the outer edges toward the centre of the sun-observer axis in accordance with einsteins theory of general relativity. So the photon energy is decreased as energy is lost gravitationally, therefore further redshifting emmitted photons from the outer edges in addition to the aforementioned rotational doppler shift and limb broadening.
 
  • #12
Labguy said:
Being just gas of increasing density, I don't really know if we can call it (the photosphere) a surface.(?) .
The layer of gas in the sun that emits visible light (the photosphere) is relatively thin, and from Earth it looks like a surface.
 

1. What are light wavelengths and why are they important to explore from the Sun's surface?

Light wavelengths are different frequencies of electromagnetic radiation that make up the visible spectrum. They are important to explore from the Sun's surface because they contain valuable information about the Sun's composition, temperature, and activity.

2. How do scientists measure light wavelengths from the Sun's surface?

Scientists use specialized instruments, such as spectroscopes, to measure light wavelengths from the Sun's surface. These instruments split the incoming light into different wavelengths and then analyze their intensity and patterns to gather data about the Sun.

3. What is the significance of studying different light wavelengths from the Sun's surface?

Studying different light wavelengths from the Sun's surface allows scientists to understand the processes and phenomena happening on the Sun, such as solar flares and sunspots. It also provides valuable insights into the behavior of other stars in the universe.

4. How do light wavelengths from the Sun's surface affect life on Earth?

The light wavelengths from the Sun's surface are essential for life on Earth. The visible light spectrum, which is a small portion of the overall electromagnetic spectrum, is responsible for photosynthesis in plants and allows humans to see. Other types of radiation, such as ultraviolet and infrared, can also impact life on Earth in both positive and negative ways.

5. Can light wavelengths from the Sun's surface be harmful?

Yes, certain light wavelengths from the Sun's surface, such as ultraviolet and X-rays, can be harmful to living organisms. Fortunately, the Earth's atmosphere acts as a shield and absorbs most of these harmful wavelengths before they reach the surface. However, it is still important to protect ourselves from excessive exposure to these types of radiation.

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