What scriptures discuss why the sky appears blue?

Question

As I discuss in this question, by far the most popular school of Hindu philosophy is the Vedanta school. But there are five other Astika or orthodox schools of Hindu philosophy: Purva Mimamsa, Samkhya, Yoga, Vaisheshika, and Nyaya. My question is about Vaisheshika, according to which atoms are the cause of the Universe. The defining text of the Vaikeshika school is the Vaisheshika Sutras, composed by the sage Kanada Kashyapa.

In any case, in Adhyaya 2 Pada 1 Sutra 5 of the Vaisheshika Sutras, Kanada argues that Ether, the substance that the sky is made of, does not possess color or the other sensory attributes that other elements possess. Now in this excerpt from his commentary on the Vaisheshika Sutras, Shankara Misra answers the objection that the sky appears to possess color:

If it be asked, "How does the perception arise that Ether is as white as curd?" we reply that it is due to the impression created by the perception of the white coloura of the rays of the sun. If it be asked "How then does the perception that Ether is blue?" we reply that it is due to the impression created in the minds of the observers who are looking at the radiance of the emerald peak lying largely extended over the south side of Sumeru mountain. It has been opined that it is due to the impression created by the eye when after traveling to a long distance it turns back and reaches its own pupil. This is not a sound opinion, because those who possess jaundiced eyes also have such impressions.

So Shankara Misra discusses two potential explanations for why the sky appears blue:

1. It's the blue glow of the emerald peak of Mount Meru

2. It's just the eye seeing a reflection of itself

Now Shankara Misra accepts the first explanation and rejects the second, but my question is, does Hindu scripture offer any other explanations for why the sky is blue? Or is this the only text that mentions this subject?

Note that, keeping with the rules of the site, I do not want people to engage in scientific speculation. I just want factual references like "the Vishnu Purana says the sky is blue because...", not attempts to show that Hindu scriptures have prefigured some modern scientific theory.

EDIT: The Yoga Bhashya, the commentary on Patanjali's Yoga Sutras attributed to Vyasa, gives the same Meru explanation:

[Sumeru's] peaks are or silver, coral, crystal, gold and jewels. There the Southern portion of the sky being colored by the radiance of emerald, is blue like the leaf of blue lotus.

Note that Jambudvipa is to the south of Mount Meru, so assuming Jambudvipa is all of Earth the southern portion would cover the whole sky. In any case, this is all the more indication that the Meru explanation might be mentioned somewhere in Hindu scripture.

Answer 1

Scriptures mostly use the term sky either to denote one of the panchamahabhoot or to compare it as pure atman.

However some puranas and scriptures have given the nature of colour of sky in terms of some analogies..

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Vishnu Purana in 2.16 gives an analogy to denote colour of sky as just apparent and illusion (but not in the context of describing colour of sky.)!

"Even as the same sky is apparently diversified as white or blue, so, soul which is in truth but one, appears to be erroneous vision distinct in different person".

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Bhagawat Purana in 10.20.4 tells illumination of sky as natural

The sky was then covered by dense blue clouds accompanied by lightning and thunder. Thus the sky and its natural illumination were covered in the same way that the spirit soul is covered by the three modes of material nature.

Bhagwata Purana in 12.8.21 tells glowing of sky due to the object which is glowing( ie. sun or moon)

Bhagvat Puran 12.8.21

21. Springtime then appeared in Markandeya's asrama. Indeed, the evening sky, glowing with the light of the rising moon, became the very face of spring, and sprouts and fresh blossoms virtually covered the multitude of trees and creepers.

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Markandeya Puran 103.9 tells Akasha (sky) as manifestations of rays of sun (ie. denoting blue colour also due to rays of sun)

I bow unto that greatest of the great,
the Sun, the first of all. (7) Urged on by this prime energy I create water, earth, air, fire, gods and various other endless objects beginning with Om; and in due order preserve and destroy them. I can never do so of my own accord. (8) Thou art fire. By thy prowess I dry up the water and create the world and perform the first cooking process of the world. Thou art, O lord, manifest over the universe and identical with Akasa.

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Mahabharat in the end of Astika parva of Adi parva tells about the light dispersion by Meru mountain but it doesn't tell sky is blue due to it. Its just in the context of lustrous nature..Further it is about golden luster..

"Sauti said, 'There is a mountain named Meru, of blazing appearance, and looking like a heap of effulgence. The rays of the Sun falling on its peaks of golden lustre are dispersed by them.

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Valmiki tells blueness of sky as optical illusion to Bharadwaja in Yogavasistha.

Chapter 3 — Valmiki Explains Desires & Describes Rama’s Pilgrimage to Bharadwaja

1 Bharadwaja said, “O brahmin, first tell me about Rama, then enlighten me by degrees with the knowledge of how to attain liberation in this life so that I may be happy forever.”

2 Valmiki replied:—
Know, holy saint, that the things seen in this world are deceiving, even as the blueness of the sky is an optical illusion. Therefore it is better to efface them in oblivion rather than to keep their memory.

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Vasistha explains about blueness of sky to Lord Rama in Yoga Vasistha as:

Yoga Vasistha Chapter 114 Description of Error

35 Rama said, “Tell me sage, what is the cause of the blueness of the sky if it is not the reflection of the blue gems on the Meru’s peak? Is it a collection of darkness (at night) by itself?”

36 Vasishta replied:—
Rama, the sky being only an empty vacuum cannot have the quality of blueness which is commonly attributed to it. Nor is it the bluish luster of the blue gems that are supposed to abound on the top of Meru. 37 Nor is there any possibility of a body of darkness abiding in the sky when the cosmic egg is full of light (which has displaced the primeval darkness) and when the nature of light is the brightness that stretches over the extraterrestrial regions. 38 O fortunate Rama, the sky which is a vast vacuum is open to a sister of ignorance with regard to its inner hollowness. 39 As one after losing his eyesight sees only darkness all about him, so the lack of the objects of sight in the womb of emptiness gives the sky the appearance of a dark scene.

The context of asking about light of Mount Meru comes here because previously astral travellers have seen blue light emitting from Meru and causing sky blue. But it was on the astral dimension.

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Conclusion: Hence scriptures describe colour of blue sky as optical illusion, as scattering of light and as reflection from Mount Meru depending on the condition and context they are describing.

Answer 2

the emerald mountain or why sky appears blue it is stated in Hinduism & Islamic cosmology that a mountain range named Lokaloka or Qaf encircles the universe & is of emerald so the reflection of it makes sky appear blue...u can find Hindu cosmology best at ISKCON pages & Qaf there's a hadith when prophet muhammad (s.a.w.)visits the qaf mountain where there were 2 cities jabulqa & jabulsa..:)

Answer 3

Sankara says in Vivekchudamani verse 195 (Swami Madhavananda translation):

But for delusion there can be no connection of the Self--which is unattached, beyond activity, and formless--with the objective world, as in the case of blueness and the like with reference to the sky.

And Madhavananda footnotes the word 'blueness' saying:

Blueness...--The sky has no color of its own, but we mentally associate blueness with it. The blueness is in our mind, and not in the sky. Similarly, limitation exists not in the Absolute Self, but in our own minds.

So not taking into account any modern scientific explanation, Sankara takes the position that it is in our own minds, which is much closer to the actual scientific explanation.