TWO SUNRISE & TWO SUNSETS IN A DAY

A group of people admiring the rise of the sun from the sea from high land. 

Watching sunrise and sunset during a hike or at the beach while hanging out with friends gives a wonderful feeling. Do you know the rise and set that we see when it just occurred is not real?

Yes, the moment the sun is raised or set is not the real rise or setting of the sun. This is not only true for the sun. But, for all the objects that we suppose to see at the horizon. Therefore, this phenomenon in the case of the sun is called “ Advanced sunrise and Delayed sunset”. The real sunrise and sunset occur only after two minutes of sunrise or sunset that we see by our eyes. This effect is due to the Physics Law connected with “Refraction of Light”.

REFRACTION OF LIGHT

Refraction of light means the bending of light when it travels through one medium to another. This occurs in two ways as when light enters a denser medium from a rarer medium and wise versa.

©Selina Concise Physics Class 10 ICSE Solutions Refraction of Light at Plane Surfaces|
 Here, “N”: Normal line and Darker black line is the interface that separates the denser and rarer mediums. Also reflected ray is a partially reflected ray (people with basic physics knowledge will face some difficulties to understand this concept. But not the refraction of light. for further studies, links are provided at the last of this article.).

HORIZON

In our language horizon is the line where the Land or the Sea meets with the sky. In other words, it is known as the tangent line drawn for a particular geographical location on the earth. Since the earth is rotating on its own axis, we see objects in the sky rise or set when it comes above the horizon or goes below the horizon respectively. This phenomenon is the main reason for the occurrence of Day and Night.

©Wikipedia: view of the horizon at the
ocean with a ship

 

view of the horizon at mountains of
 Serra do Tucano, Brazil

 

ADVANCED SUNRISE AND DELAYED SUNSET

Up to now, we know about the refraction of light and the horizon. Now let's get into our topic.

Let’s assume that a person is standing at a place and looking at the eastern horizon and watching the sunrise. At this moment, first, he sees the twilight, and then when the sun is rising a bright light spot.

fig(a): Twilight sky during sunrise

 

©ARC: fig(b): corresponding sketch diagram of fig(a).  [not for scaling].

 

fig(c): Rays of sun scattered everywhere during Sunrise.

 

©ARC: fig(d): corresponding sketch diagram of fig(d), the sun rising above the horizon.
[not for scaling] 

We think that the sunrise occurs as above. But, the earth has an atmosphere and outer space is a vacuum. Since our sun is a light source and light travels in a straight line, definitely, the light ray from the sun should get slower and bend towards the normal line due to the atmospheric layers. Here, our earth’s atmosphere act as a denser medium, and outer space act as a rarer medium.

Therefore, the real scenario happens like in the following diagram:

©ARC: fig(e): Positions of the real sun and apparent sun
represented with a ray diagram during sunrise (sunset). [not for scaling]

In reality, the earth is revolving around the sun. Not the sun orbiting the earth. Therefore, the above effect happens relative to the earth.  Here you can see the sun is below the horizon. In reality when an object below the horizon will not be visible. But, due to the effect of “Refraction of Light” when a particular object (here sun) is located at a particular angle below the horizon line (mostly closer to the horizon), then it is possible to see that object (here sun) due to the refraction of light in the atmospheric layers.

©Wikipedia: This diagram of the Sun at sunrise (or sunset) shows the
effects of atmospheric refraction.

As in Fig(e), if we backtrack the refracted two light rays we can see a virtual image (of the sun) is forming above the horizon due to the deviation in angles of refracted rays from primary light rays from the sun.

As a result, we see the sunrise even before it actually gets rises above the horizon. Also, this same effect makes the sunset a delay. Because the moment the sun goes below the horizon its refracted image still remains above the horizon and makes it visible as it is not still get set.

This is the reason that earlier sailors do not use the stars at the horizon for their navigation. Because the stars at the horizon are apparent images of that same stars. Therefore it will not show the correct direction.

WHAT DOES THE CREATOR SAY?

The creator of the universe best knows how the universe works. He says in his final revelation (Holy Quran):

| “…So which of the favors of your Lord would you both deny?. [He is] Lord of the two (sun)rises and Lord of the two (sun)sets. So which of the favors of your Lord would you both deny?…"

 [Chapter:55, Verse:16-17] 

Click here for the full chapter with original language with pronunciations and word by word translation |

Here we took the translation as referring to the sun. But, originally it does not says only for the sun. It generally talks about the things which frequently rise and set on both the East and West horizons. In Arabic, we can’t take the direct translations of words. It will vary according to the situation, tense, person, things and etc. If we analyze each and every sentence deeply we will realize more facts on this verse. To make this article simple here, we discuss only this “Advance sunrise and delayed sunset” concept.

In this modern world, it is easier for us to calculate and observe the concepts of physics with technological devices and other methods. But, how a person in a desert without knowing even to read can explain the above concept of physics with a single verse?

There are uncountable facts in his final revelation, which the creator explains to us about his power, ability, and authority in the universe. 

Exegesis by: Raiz-ul-Haque

If you interested to know more about:

 1. Creator (short video): click here

 2. Life of his last Prophet and Messenger (full video playlist): click here

3. Chapter 55 (Exegesis as a video): click here

4. Ray optics (full video playlist): click here