The Brahmanda outer shell or covering of our inner small universe is made up of 7 material layers that is 44 quadrillion, 444 trillion, 444 billion miles in diameter.

Understanding our "Brahmanda housing dome" which is a massive egg shaped yet almost spherical covering that houses our small material universe deep within it.

Our individual universe, with its 14 planetary systems, is found deep inside the massive Brahmanda shell that surrounds and encases our small universe within known as Bhu-Mandala which is just 4 billion miles in diameter.

All the 14 Planetary Systems are in the stem coming from the Body of Garbhodakashayi Vishnu explained in Srimad Bhagavatam canto 1 Chapter 3 Text 2 -

"Within the stem of the lotus there are fourteen divisions of planetary systems, and the earthly planets are situated in the middle".

However, there is a deeper understanding here as well

Srila Prabhupada - "All these planetary systems are scattered over the complete universe, which occupies an area of "two billion times two billion square miles". SB 2.5.40-41, Purport

Question - "I have heard that all of the planets are in the stem of the lotus from which Brahma took birth. How can that be?

Answer by the late Sadaputa dasa - "This is stated in SB 1.3.2p. Since the planetary systems are distributed throughout the universal globe, it must be that the stem encompasses everything within this globe.

We should note that the standard pictures we see of Brahma sitting on the lotus flower are three-dimensional representations of a scene that cannot be seen using our ordinary senses.

Although the pictures show the lotus stem emerging from the navel of Garbhodakashayi Vishnu, Brahma himself was unable to locate the origin of the stem.

Thus, part of the scene was beyond the senses of Brahma, and so it is certainly beyond the reach of our senses.

We also note that the planetary systems were created by Brahma from the lotus (SB 3.10.7-8).

This suggests that these systems were produced by transforming the substance of the lotus".

The Brahmanda outer shell or covering is made up of  7 material layers that is 44 quadrillion, 444 trillion, 444 billion miles in diameter.

The 7 layers are - (From S B Canto 6 Chapter 16 Text 37)

1 - EARTH,
2 - WATER,
3 - FIRE,
4 - AIR,
5 - SKY,
6 - TOTAL MATERIAL ENERGY,
7 - FALSE EGO.

Srimad Bhagavatam says there are millions of individual Brahmanda universes coming from Maha Vishnu making up the entire material creation (1/4 of the Spiritual Sky) that also house their own inner universe.

All smaller universes inside their Brahmanda are of different sizes, some, like ours, are only 4 billion miles in diameter.

The "4 billion miles (500,000,000 Yojanas)" diameter of our universe with its 14 planetary systems is one of the smallest.

In Srimad Bhagavatam Canto 3 Chapter 26 text 52 in Purport Srila Prabhupada states -

"The space within the hollow of the universe cannot be measured by any human scientist or anyone else."

This also suggests that something unexpected must happen to space (as well as time) as one approaches the outer universal Brahmanda shell, for it hardly seems impossible to measure a distance of 2 billion miles in ordinary space.

Srila Prabhupada - ''We have to imagine that these universes (Brahmandas), which according to our limited knowledge are expanded unlimitedly, are so great that the gross and subtle ingredients—the five elements of the cosmic manifestation, namely earth, water, fire, air and sky, along with the total material energy and false ego—are not only within the universe but cover the universe in seven layers, each layer ten times bigger than the previous one.

In this way, each and every universe is very securely packed, and there are numberless universes. All these universes float within the innumerable pores of the transcendental body of Mahā-Viṣṇu.

It is stated that just as the atoms and particles of dust are floating within the air along with the birds and their number cannot be calculated, so innumerable universes are floating within the pores of the transcendental body of the Lord. For this reason, the Vedas say that God is beyond the grasp of our knowledge. '' Krsna Book 87

We CANNOT see from one universe to another, this is because our individual universe is surrounded and encased by 7 thick material layers that is our outer egg shaped universe called a Brahmanda.

So it is impossible to see the millions of other Brahmandas outside our inner universe (inside a massive Brahmanda) because of those 7 thick material layers that only rare mystic yogis and advanced devotees like Arjuna can see and pass through.

So of course Krishna and Arjuna did not encounter such limitations that we experience with the combination of these elements like earth, water, fire all gross elements as Bhagavad Gita explains.

Srila Prabhupada - ''The Lord is not visible to the eyes of ordinary men, those who are beyond the covering layers because of their transcendental devotional service can still see Him''. Krsna Book 87

We cannot see through our Brahmanda that surrounds and encases our small universe, Srila Prabhupada is clear on this

Srila Prabhupada - ''Lord Krishna and Arjuna crossed over the great region of darkness covering the material universes. Arjuna then saw the effulgence of light known as the brahmajyoti. The brahmajyoti is situated ''outside the covering of the material universes'', and because it cannot be seen with our present eyes, this brahmajyoti is sometimes called avyakta''. Krsna Book, 89

Srila Prabhupada - ''Each universe is covered by various layers of material elements (The 7 layers of the outer Brahmanda covering), and therefore although the universes are clustered together, we CANNOT see from one universe to another. In other words, whatever we see is within this one universe. In each universe there is one Lord Brahmā, and there are other demigods on other planets, but there is only one sun''.- (Srimad Bhagavatam Canto 5 Chapter 21 Text 11, Purport)

Every universe is covered by seven layers—earth, water, fire, air, sky, the total energy and false ego—each ten times greater than the previous one. There are innumerable universes besides this one, and although they are unlimitedly large, they move about like atoms in You. Therefore You are called unlimited [ananta].

PURPORT

This verse describes the coverings of the universe (saptabhir daśa-guṇottarair aṇḍa-kośaḥ).

1 - The first covering is EARTH,
2 - the second is WATER,
3 - the third is FIRE,
4 - the fourth is AIR,
5 - the fifth is SKY,
6 - the sixth is the TOTAL MATERIAL ENERGY,
7 - the seventh is the FALSE EGO.

Beginning with the covering of earth, each covering is ten times greater than the previous one. Thus we can only imagine how great each universe is, and there are many millions of universes". (Srimad Bhagavatam Canto 6 Chapter 16 Text 37)

As confirmed by the Lord Himself in Bhagavad-gītā (BG 10.42): -

athavā bahunaitena
kiṁ jñātena tavārjuna
viṣṭabhyāham idaṁ kṛtsnam
ekāṁśena sthito jagat

"But what need is there, Arjuna, for all this detailed knowledge? With a single fragment of Myself I pervade and support this entire universe."

The entire material world manifests is only one fourth of the Supreme Lord's energy. Therefore He is called ananta''.

In the purport in Srimad-Bhagavatam Canto 2 Chapter 2 Text 28-

"Śrīla Śrīdhara Svāmī confirms that a part of the material nature, after being initiated by the Lord, is known as the mahat-tattva.

A fractional portion of the mahat-tattva is called the false ego. A portion of the ego is the vibration of sound, and a portion of sound is atmospheric air.

A portion of the airy atmosphere is turned into forms, and the forms constitute the power of electricity or heat.

Heat produces the smell of the aroma of the earth, and the gross earth is produced by such aroma. And all these combined together constitute the cosmic phenomenon.

The extent of the cosmic phenomenon or our individual universe is calculated to be diametrically four billion miles in size.

Then the outer covering known as the Brahmanda shell begins.

The first covering of Earth is calculated to extend forty billion miles, (10 times the size of the inner universe) and the subsequent coverings of the universe are respectively of water, fire, air, sky, total material energy, false ego one after another, each extending ten times further than the previous.

The fearless devotee of the Lord penetrates each one of them and ultimately reaches the absolute atmosphere where everything is of one and the same spiritual identity.

Then the devotee enters one of the Vaikuṇṭha planets, where he assumes exactly the same form as the Lord and engages in the loving transcendental service of the Lord.

That is the highest perfection of devotional life. Beyond this there is nothing to be desired or achieved by the perfect yogī."

It is also says in Srimad Bhagavatam Canto 3 Chapter 26 Text 52 -

Srila Prabhupada  - "The dimensions of the universe are estimated here. The outer covering is made of layers of water, air, fire, sky, ego and mahat-tattva, and each layer is ten times greater than the one previous.

The space within the hollow of the universe cannot be measured by any human scientist or anyone else, and beyond the hollow there are seven coverings, each one ten times greater than the one preceding it.

The layer of water is ten times greater than the diameter of the universe, and the layer of fire is ten times greater than that of water.

Similarly, the layer of air is ten times greater than that of fire. These dimensions are all inconceivable to the tiny brain of a human being."

In Srimad Bhagavatam Canto 3 Chapter 29 Text 43 Prabhupada says -

Srila Prabhupada  - "It is understood from this verse that all the planets in outer space are floating, and they all hold living entities.

The word svasatam means "those who breathe," or the living entities. In order to accommodate them, there are innumerable planets. Every planet is a residence for innumerable living entities, and the necessary space is provided in the sky by the supreme order of the Lord.

It is also stated here that the total universal body is increasing. It is covered by seven layers, and as there are five elements within the universe, so the total elements, in layers, cover the outside of the universal body.

The first layer is of earth, and it is ten times greater in size than the space within the universe;

The second layer is water, and that is ten times greater than the earthly layer;

The third covering is fire, which is ten times greater than the water covering. In this way each layer is ten times greater than the previous one.

In the above mentioned purports to Srimad  Bhagavatam seemingly gives contradictory information that can make things confusing to scholars. (SB 2.2.28 and SB 3.26.52 says it is water and SB 3.29.43 says it is earth)? Furthermore, what is the breadth of the first layer?

The purport to Srimad Bhagavatam Canto 2 Chapter 2 Text 28 says it is 80,000 000 miles while the diameter of the universe is 4 000,000,000 miles. This does not add up and is seemingly incorrect.

Srimad Bhagavatam Canto 3 Chapter 29 Text 43 says the first layer is 10 times greater in size than the space within (our 4 billion mile diameter inner universe) the universe.

BUT 80 million miles diameter is definitely not 4 billion miles X 10, this is a possibly a typing error in the editing of the Book.