In astrology the Sun is called the atma-karaka or “significator of the soul.” The Sanskrit karaka is used frequently in astrology. It means “significator.” In each individual chart the planets take turns as karakas for different aspects of life according to their degree positions. Thus any of the nine planets can become the temporary atma-karaka for a particular chart. But in astrology the effulgent Sun is the overall atma-karaka. Now, the word atma—self—is flexible and the definition refers to the level of the person’s realization. In ordinary horoscopes, those of body-conscious materialists, atma might refer to the false ego. But for self-realized personalities or devotees, atma naturally refers to the eternal individual spiritual spark—the actual self. Thus in his highest aspect in astrology the Sun represents realization of the eternal position as spirit soul, part and parcel of the Supreme Lord Shri Krishna, and joined to Him through loving service. Krishna tells Arjuna in verse 10.21: jyotiṣāṁ ravir aṁśumān, “Among lights I am Ravi—the radiant demigod of the Sun.”
In verse 13.34 Lord Krishna gives the example of His representative the Sun to explain different points in a single verse. Addressing Arjuna as the son of Bharata, the Lord says, “… As the Sun alone illuminates all this universe, so does the living entity, one within the body, illuminate the entire body by consciousness.” From this verse the reader understands that not only is he an eternal spiritual entity, but that the Universe has only one Sun. Scientists often bluff that the distant stars are “Suns” in distant “solar systems.” However, this inaccurate theory is disputed here by the Supreme Authority with the words kritsnan lokam imam ravih: “The single Sun illuminates the entire Universe.” In chapter eleven, wherein Lord Krishna displays His Universal Form or Vishwarupa to Arjuna, the Lord’s stunned disciple responds with the words (Bg.11.12), “If hundreds of thousands of suns rose up at once into the sky, they might resemble the effulgence of the Supreme Person in that universal form.” From this verse we can understand that the brilliant and blinding Sun we see in the sky each day contains but a tiny fragment of the brilliance of the Supreme Lord. Astonished, Arjuna declares divi sūrya-sahasrasya bhaved yugapad utthitā: “If thousands of Suryas were present at once …” they might be something like the Supreme Lord’s Vishwarupa. Yet, as Krishna says elsewhere in the Gita, these forms of the Lord represent but a “spark of His splendor” (10.41). Arjuna compares Krishna to Arka, the Sun, in verse 11.17 (dīptānalārka-dyutim aprameyam): “Your form, adorned with various crowns, clubs and discs, is difficult to see because of its glaring effulgence, which is fiery and immeasurable like the Sun.” Even in his Universal Form, the Supreme Lord is holding gadas and chakras and wearing shining helmets. Thus the Supreme Lord is always a person and the impersonal aspect or His divine effulgence is subservient to the spiritual form of the Personality of Godhead.
Bhagavad-gita 10.41 A sampling of Krsna's infinite manifestations, both in the spiritual and material worlds.
Bhagavad-gita 11.13 (9) Krsna's universal form is displayed to Arjuna. Still the Lord does not loose His original eternal identy,. He remains seated on the chariot with Arjuna.
What Arjuna saw was indescribable, yet Sañjaya is trying to give a mental picture of that great revelation to Dhṛtarāṣṭra. Neither Sañjaya nor Dhṛtarāṣṭra were present, but Sañjaya, by the grace of Vyāsa, could see whatever happened. Thus he now compares the situation, as far as it can be understood, to an imaginable phenomenon (i.e. thousands of suns).