Astronomers find that light emitted by a particular element at one edge of the Sun has a slightly higher frequency than light from that element at the opposite edge. What do these measurements tell us about the Sun’s motion?
It indicates the sun rotates, so the side rotating away from us is moving more slowly (relative to us) than the side rotating towards us.
Of course, a tiny part of the shift is due to our revolving around the sun, but that doesn't count much.
thank you, is this related to the doppler effect
It is exactly the Doppler effect.
Thank you
To understand what these measurements tell us about the Sun's motion, we need to apply the principle of the Doppler effect. The Doppler effect is a phenomenon that occurs when there is relative motion between a source of waves (such as light) and an observer. It causes a change in the frequency (or color) of the waves as perceived by the observer.
In the case of the Sun, if the light emitted by a particular element at one edge has a slightly higher frequency than the light from that element at the opposite edge, it indicates that there is a motion component along our line of sight. This motion could be either towards us or away from us.
The Doppler effect in astronomer's terms is known as the "redshift" and "blueshift" effect. A redshift occurs when there is a motion of a source away from the observer, causing a shift towards the red end of the electromagnetic spectrum. Conversely, a blueshift occurs when there is a motion of the source towards the observer, causing a shift towards the blue end of the spectrum.
So, in the case of the Sun, if the light from a particular element at one edge has a higher frequency (blueshift) than the light from that element at the opposite edge, it suggests that the Sun is moving towards us. On the other hand, if the light has a lower frequency (redshift) at one edge compared to the opposite edge, it indicates that the Sun is moving away from us.
In summary, the measurements of the slightly higher frequency of light from a particular element at one edge of the Sun compared to the opposite edge suggest that the Sun is moving towards us, while a lower frequency would indicate that the Sun is moving away from us.