# The Colors of The Moon (Doppler Effect)

• B
• dom_quixote
In summary, The conversation discusses the possibility of detecting the Doppler effect of sunlight reflected by the Moon from the Earth's surface. It is mentioned that the solar rays reaching the Moon and Earth are parallel, the lunar orbit lasts 27.322 days and is elliptical, and the average distance between the Moon and Earth is 384,000,000 meters. The perimeter of the average lunar orbit is calculated to be 2,412,743,158 meters with a speed of 1,022.7 meters per second. The question is raised if there is enough technology to detect the Doppler effect, with the response that the effect may be too small to detect. Reference is also made to the Balmer spectre and the frequency
dom_quixote
Hey guys!

I will pass an illustrated problem, below.

- We know that the solar rays that reach the Moon and Earth are practically parallel;

- We know that the lunar orbit with respect to Earth lasts 27.322 days or 2,360,621 seconds;

- We know that the lunar orbit with respect to the Earth is elliptical;

- We know that 27.322 days the distance between the Moon and Earth varies between 362,600 km and 405,400 km.

In order to simplify our calculations, let us consider an average circular orbit:

[405,400,000 m + 362,600,000 m] / 2 = 384,000,000 m

The perimeter of the average lunar orbit is equal to:

2 * pi * 384,000,000 m = 2,412,743,158 m

The speed of the Moon relative to its average orbit is:

2,412,743,158 m / 2,360,621 s = 1,022.7 m/s

Do we have enough technology to detect the Doppler effect of sunlight reflected by the Moon from the Earth's surface?

From your numbers I calculate v/c = 3.4E-6. Balmer spectre of n=3 has wave length of 656 nm would undertake the wave length difference of 2.2 pico meter. I am not good at relevant technologies at all but suppose the effect is too tiny to detect.

dom_quixote
There are some narrow lines:

NIST

dom_quixote and anuttarasammyak

## 1. What causes the colors of the moon to change?

The colors of the moon change due to the Doppler Effect, which is caused by the relative motion between the moon and the observer. As the moon moves closer to the observer, its light waves appear shorter and therefore bluer. As it moves away, the light waves appear longer and redder.

## 2. How does the Doppler Effect work?

The Doppler Effect is a phenomenon where the frequency of a wave appears to change when the source of the wave is in motion relative to the observer. This is due to the compression or stretching of the waves as the source moves closer or farther away.

## 3. Can the colors of the moon be seen with the naked eye?

Yes, the colors of the moon can be seen with the naked eye, but they may be difficult to distinguish without a reference point. It is easier to see the color changes when the moon is near the horizon, as it appears larger and the color differences are more noticeable.

## 4. Are there specific colors associated with the moon's phases?

Yes, there are specific colors associated with the moon's phases. During a full moon, the moon appears white or yellowish. During a new moon, the moon appears dark or black. The colors in between vary depending on the moon's position and the observer's location.

## 5. Does the Doppler Effect affect other celestial bodies besides the moon?

Yes, the Doppler Effect affects all celestial bodies, including stars and planets. However, the color changes are most noticeable with the moon due to its proximity to Earth and its large size in the night sky.

• Astronomy and Astrophysics
Replies
33
Views
3K
• Astronomy and Astrophysics
Replies
21
Views
5K
• Astronomy and Astrophysics
Replies
2
Views
2K
• Astronomy and Astrophysics
Replies
17
Views
2K
• Classical Physics
Replies
4
Views
729
• Astronomy and Astrophysics
Replies
10
Views
2K
• Astronomy and Astrophysics
Replies
30
Views
3K
• Astronomy and Astrophysics
Replies
4
Views
2K
• Astronomy and Astrophysics
Replies
3
Views
925
• Astronomy and Astrophysics
Replies
4
Views
2K