|Basically this is meant to be rotation axis of earth. Its length is 100,000 yojanas ( 1 yojana = 1000 part of equatorial diameter = 12800 kms approx. here). The disc shaped zone around earth in plane of ecliptic is called Jambu-dvipa of 50, 000 yojana radius in Bhagavata purana, skandha 5, Vishnu purana 2/7-8 etc. That is exclusive gravitational zone of earth in which a body will revolve round earth. Moon is at about 61r distance, r = radius of earth.
Vishnu purana 2/8 tells about Shishumara-chakra which is perpendicular to ecliptic plane around which earth’s axis rotates in 26000 years, called precession of equinoxes (also explained by Al-Biruni). This has been called Naka-svarga in Vedas (Madhusudan Ojha–Brahma-siddhanta etc.). Axis of solar system and galaxy (Parameshthi mandala) have been called Lingas in space in Shiva-purana.
Kutub-minar is model of Sumeru of earth in space. At Delhi, its semi-vertical angle is equal to difference between true and mean latitude there. That was not known after Mahabharata till 1850 AD. In 456 BC at start of Sri-Harsha shaka (Al-Biruni, Abul Fazal), it was place of northern most position of moon on earth surface (inclination of earth’s axis 23.90 + inclination of moon’s orbit with ecliptic 5.020)-Refer my commentary on Siddhanta-Darpana, chapter 16. So, ‘Chandra’ has been written on iron pillar there. A pillar of 12 units (called Shiva-linga of 12 angula in Shiva purana) was used to measure time and latitude of a place. It is called Shanku in surya-siddhanta etc. Smallest shadow is at noon time and locus of shadow end around that time is in shape of a ‘Kutup’ called kuppi (funnel, thistle-kip) in Hindi. So, the muhurtta at noon time is called Kutupa-muhurtta. By bisecting the shadow line equi-spaced from noon, say at 11 and 13 hrs-we get north–south direction. This is explained as traversing in books of astronomical survey for M.Tech (civil). The bisection is by common part of two circles in shape of a ’Mina’ (fish), so the pillar is called Kutup-Mina or Kutub-minar. Magnetic compass does almost same work, so it is called Kutub-numa. In that also, needle floating on mercury is called ‘Mina’. Local references of latitude also have been given name of fish like Rohataka ( almost at longitude of Ujjain) and Hilsa near Patna (100 east of Ujjain).
Mapping of earth surface of north (and south) hemisphere was in 4 sheets of 900 longitude width. It was centered round north pole called Meru or Sumeru. Bharata-varsha (India) has been called one of the 4 petals of that lotus (earth surface) as it roughly extends 450 west and 450 east of Ujjain. Thus, Meru has 4 faces and its linga (symbol) has square base-called Svayambhu linga as in Kaaba of Arab at west end of Bharata. Pyramids were constructed 450and 1800 west of Ujjain in Ezypt and at Mexico (called Siddhapura in Surya siddhanta)-Valmiki Ramayana, Kishkindha kanda (40/54, 64). South pole was called Kumeru (opposite to Sumeru in north). Aryabhata (Kali 360 = 2742 BC) has stated that north pole is in water and south pole on land mass. South pole is joint of 2 land masses-called Yama-dvipa. Yama is lord of south and Yama also means twin or double.Till 1985, it was not confirmed whether south pole is in water channel between 2 land masses or on land itself. Only by echo-sounding, in 1985, it was known that it is actually on land. Nearest land mass is New Zealand which has again 2 islands. So it was called Yama-koti-Dvipa (at end of Yama dvipa). Actually, Yama star (southern Crux) has same southern latitude as this island. Its south western tip has been called Yama-koti-pattana (port of Yama–koti)-stated to be 900 east of Ujjain in Surya-siddhanta etc. There should be a pyramid at this point also-probably it is submerged in ocean now.
Largest land mass is Jambu-dvipa (Asia + Europe). Center of mountain ranges is called Pran-Meru (Eastern Meru) or Pamir. Human Brahma was here at Pushkara (120 west of Ujjain and 350 north where maximum day length is of 16 hours). This is now called Bukhara on north of ancient Persia, now in Uzbekistan. 4 highways went in 4 directions, so Brahma was called 4 faced. Till today convention of script by him continues- north east part writes from up to down, south west to left and south east (India) to right side. North west part uses Sankhya script of 52 letters-see my article ‘Vedic origin and classification of scripts’ on www.scribd.com/Arunupadhyay. Opposite to that is Pushkara-dvipa (south America) having Apara-Meru (western Meru) at Peru from where 4 highways emanated in 4 directions from Kuzco as in Pran-meru. In between is central Meru at equator in Kenya (mount Kilimanjaro). Sri Vinay Jha used it for the first time for rain forecasting as it starts from equator region only and reached India as rains after Adhana (in womb) period of 6.5 months (193 days) as in Brihat-samhita of Varahamihira. The places around it have still the name of Meru. (see website of Sri Vinay Jha).