Children wonder that how the sunlight falls in certain areas in the house at different times. It will be there for some days for some time and then disappear.  Even they get old then also take it as a wonder that in the well constructed house with many windows and doors, on some days, light still falls on certain areas only. Closing a door or window, light disappears, but the wonder is, the closing door or window is never in the direction of the Sun.

Most people must be knowing that vitamin D deficiency leads to less sleep provided there is not much distress, and it.can be obtained through sunlight. Walking in good sunlight for some time is sufficient for getting Vitamin D. Standing in light for too much time gives some sort of irritation and itching and piercing effect on body. In summer sunstroke could be possible due to excess heat of the sunlight. One has to be very careful not to move in the afternoon unless warranted and that too should be undertaken with precaution like water ready in hand. Within minutes one mayfall down and get unconscious.

1. Sunlight
In the day time the principal source of light is the sunlight. The sunlight spreads everywhere. It is due to the light falling on objects, they are visible to us. The sunlight not only brings light, it also brings heat. This heat is more felt in the afternoon. If this heat is concentrated, it can burn things - create fire. It is the ultra violet part of sunlight which provides more heat.
(Is it the reason people coming from hot Sun are prone to more anger?)

Many people stand for a while in the sunlight after their oil massage in the body. The heat of the sunlight with the oil will help the oil absorbed in the body and affect on the body. Probably on account of the same the oil bath is asked to take in the morning, so the one can sit in the sunlight after massaging the oil in the body. One can warm water also under the sunlight. Water using solar water heaters has any more immune property? Just imagine, what would have been the condition of our earth if sunset and sunrise were not there. The Sun neither moves left or right, we feel it moving so because our Earth rotates around him.

2. Moonlight
After the Sun's light in the daytime, Moon is the light giver in the nighttime. As the Sun neither moves left or right, we feel it moving so because our Earth rotates around him. Similarly the Moon also never rises or sets. But since he rotates around the Earth, we feel that he is rising and setting. Due to rotation of the earth and rotation of the Moon, we feel the variation in the size of Moon. But Earth's rotation is not felt by us since we are on Earth, other than in very rare occasions - it is during earthquakes. Earthquakes make us realize that Earth can also shake. We say, Moon rises and Moon sets because of the rotation of Earth and the Moon. If this rotations are not there, there is no Prathamaa or Ekaadashee at all Moon, Moon rise and Moon set does not coincide with sunrise and sunset. On many days we can see Moon well before sunset and disappearing after hours of sunrise.

Moon is not an object emanating light. It reflects light from the sunlight falling on it. Though we know it, still we say it moonlight, not Moon reflecting light. Probably because of the nature of some specific planet, the reflected light is not hot. As we receive the light of stars, Moon too receives the light of other stars than sunlight. So moon reflects light from all these sources also.

3. The Star Light
On many days, when Moon is not in the sky and there is less cloud, we can see bright stars in the sky. Many times, we feel, the stars give as much light or still more light than Moon on such occasions. It is real enjoyment to look at stars, and their light flickering. The planets, being closer, have no such visible flickering. If we closely observe certain stars in which birth has taken place have special effect on the person. Just one point - People born in Maha Nakshatra and Devagan Nakshatra are found to be soft and good natured. Though it cannot be explained, but there is sure some effect of stars on human life. stars, specially if the children are born in the morning.

4. Light From Other Planets.
The two planets Mercury and Venus are below the earth. Hence the light reflected by them also fall on our earth. We are able to see the planets just like the stars. The planet light is differentiated from star's light being no visible flickering. Further their light could be more bright also.

1. Sandhyaa Vandan
Many Hindu perform Sandhya vandanam in the morning and evening. Sandhya is the time, sun rise and moon set in the morning and moon rise and sun set in the evening. Both during rising and setting time, we can see the sun reddish hot and 99% circle. In the after noon the Sandhyaa is called Madhyaanik, changing from AM to PM (crossing meridian). We have to perform Madhyaanik also, but the true fact is the people performing it are fewer than. While performing Sandhyaa Vandan, why Yam Dharm is also worshipped facing South. Because Yam is the son of Sun God. What a wonder - both Saturn and Yam are related as first cousins - one is the judge of our Karm in this life on Prithvi, and the other one after life in the other world.

2. Sunlight Comes after light years.
The light emanated from the Sun reaches us after light years - a long period of time. So either it is a cloudy day or bright day, Sun emanates light, it continuously travels, reaches us. In the mean while the light travels through many layers of atmosphere.

3. Rectilinear Propagation of Light
In lower classes it is taught that the light travels in straight line and that is called the rectilinear propagation of light. Not only sunlight, but even light emanated by objects also travels in straight line. It was easy to digest looking at the morning Sun, light reaches as a white straight line, but looking up the lighted electric bulbs of higher wattage, it became very clear - light travels in straight line. But in higher classes one studies wave theory of light. That is, it does travel in straight line but the straight line appearing is actually is in the form of wave and not a perfect straight line.

4. Sunlight and Rainbow
The relation between the rainbow and the Sun does not become clear in childhood days. Continuous drops of water and light passing through them creates rainbow can be digested very easily, but the rainbow is the refraction through the rain drops of sunlight is difficult to be digested.

5. The VIBGYOR
The seven light content of the sun light could be easily seen through a triangle type glass called Prism. The refracting light will show the different light colors. Even our color concept and mixing and getting new colors have come from it.

6. Mythology of the Sun
Sun God is the son of sage Kashyap from his wife Aditi. Sun married Sanjanaa, daughter of Vishwakarmaa. They had a son Shani (Saturn). Sanjanaa left the Sun not able to bear his heat, creating a replica woman of herself Chhaayaa. Sun had a son Yam and daughter Yamee from Chhaayaa, not knowing that she was not Sanjanaa. In due course of time, Yamee later became Yamunaa river. Shani could find a difference in the nature of Chhaayaa with Yam and himself. Not able to tolerate, he kicked Chhaayaa and reported the matter to his father Sun. Sun could not digest this. Chhaayaa cursed Shani to become lame. Hence the Saturn takes more time to travel. Knowing all matter, Vishwakarmaa, the father-in-law shaved of some part of Sun's body. They became the other planets. He joined Sanjanaa again. This mythological legend gives reasoning for the origin of other planets.

7. Sun and Astrology
Sun is exalted at Mithun Raashi (Gemini Sign) - May-June. During that time it is very hot. Many Sun strokes occur during the time. In the Tulaa Raashi (Libra Sign), the Sun is in debilitation. During that time, Tulaa Varsh occurs. Moon is in exaltation in Vrishabh Raashi (Taurus Sign). Period of coolness. During the time heavy rain fall occurs. In deciding the exaltation etc, whether the climatic condition was considered or the climatic condition occurred from the exaltation and debilitation?

8. Sun Temples
There are many Sun temples. Were the beginning of the sun temples related with pacifying the Sun to reduce excess light and heat?