There are many stories about the origin of Bengaluru’s name. One popular apocryphal version recounts the tale of a king from the Hoysala dynasty coming to the city in the 12th century on a hunting spree and losing his way. The hungry king, the story goes, was given a traditional welcome by an old woman, who offered him water and boiled beans—benda kaalu in Kannada. The grateful king was supposed to have named the settlement “Bendakaaluru”: The town of boiled beans. This evidently metamorphosed to Bengaluru in due course of time.

However, the recent discovery of a ninth century temple inscription—referring to the name of Bengaluru—has put paid to the story and, literally, relegated it to an urban legend.

There is no such doubt regarding the role played by the Kempe Gowda bloodline—the feudatory rulers under the Vijayanagara empire—who founded the city of Bengaluru. Named after their family deity’s consort, Kempamma, Kempe Gowda I founded the city in 1537. He soon constructed a mud fort with a protective moat, and established markets in its premises.

Kempe Gowde I is also credited with the construction of several lakes or keres in and around this original mud fort, for the purposes of drinking water and irrigation: the Dharmambudhi lake, the dried bed of which today houses Kempegowda Bus Station, and the now decrepit Kempambudhi lake are some of the most noteworthy ones. His grandson, Kempe Gowda II, also built many lakes and watchtowers around the city.

Many of these medieval lakes that once slaked the city’s thirst and watered its crops have today been ravaged by urbanization and the ensuing encroachment. Kempe Gowde I also championed the construction of several temples around the town; one of the earliest such temples that was renovated and constructed outside the fort’s perimeter was the Gavi Gangadhareshwara temple.

And it was to this temple that I boarded the No. 35 bus on 14 January. The time was 3.10pm and the bus was uncommonly crowded. On most days, buses starting from the Kempegowda Bus Station tend to be crowded. Bengauluru is a city in the throes of agonizing urbanization. Everything is crowded.

But this was a Saturday. And yet, the bus thronged with people. All of them, like me, were on their way to the bus stop near the swimming pool in Gavipuram. We were going to witness a breathtaking celestial phenomenon.

To visit the Gavi Gangadhareshwara temple, alight at the bus stop overlooking Kempambudhi Lake. A short walk up the road leading south takes you to the temple.

From outside its walls the temple looks unremarkable. But on stepping into the forecourt several distinctive features catch the eye. The main idol of the temple is inside a cave that devotees descend into via steps. Unusually for a South Indian temple the complex is not aligned to any of the cardinal directions—it faces south-west. This is perhaps the first clue to the temple’s astrophysical relevance, and why it is such a draw for the hundreds of devotees who throng around me. There are more clues.

In the forecourt stand two monolithic structures, named Suryapana and Chandrapana—each consisting of a massive disc atop a supporting pillar, like giant stone lollipops. Engravings of sitting bulls on the discs face each other. The discs are identical in size and have a diameter of about 6ft. Grooves cut into the discs at right angles to each other, on both faces, giving them the appearance of a sniper rifle’s crosshairs.

Along with these structures are the objects associated with the iconography of Shiva—the trishula (trident) and the damaru (an hourglass-shaped, two-headed drum). In between the two discs there is a brass dhwajasthambha (flagstaff), and a small cubicle housing a statue of Nandi, Shiva’s bull mount.

The outer mantapa (vestibule) leading to the cave has pillars in the Vijayanagara style, set into the floor, a few inches below the level of the forecourt. The entrance to the cave is flanked by statues of Shiva’s dwarapalakas (doorkeepers).

A small flight of stairs leads one down to the cave that is hardly 6ft high; the height tapers off further into the shrine. In the cave temple the presiding idol, a Shiva linga, is surrounded by several smaller deities and sages, and the two pradakshine (circumambulatory) paths. Another statue of Nandi faces his master. There are also entrances into two secret tunnels which, according to legend, lead to Shivaganga and Varanasi.

The low height of the pradakshine paths lends itself to the Hindu customary practice of bowing one’s head while paying obeisance to god or one’s elders. A steady, thin stream of water always flows through the cave, next to the main idol. This undoubtedly harkens back to the myth of Ganga (the personification of the holy river) getting entrapped in Shiva’s hair and emerging from his matted locks as a small stream and thence flowing onto the earth.

Hence, the temple derives its name from this combination of topographical features and mythology: gavi, meaning cave, and a representation of Shiva as Gangadhareshwara (dhara meaning adorning and eshwara meaning divinity). Thus, Gavi Gangadhareswara means the Cave of the Lord who adorns the Ganga. The name of the locality, Gavipuram (puram meaning dwelling or settlement), too draws its name from the cave temple.

I was here, along with hundreds of others, on the auspicious occasion of Makara Sankranti, which marks the entry of the sun into the zodiac sign of Capricorn. Each year on this day the temple experiences a huge influx of devotees, eager to witness the headlining celestial event. Anticipation builds up to a fever pitch. In large tents specially put up to house visitors, hundreds of eyes eagerly watch TV monitors broadcasting live pictures from inside the cave. Elsewhere all over Bengaluru, thousands more wait anxiously as they watch live TV broadcasts.

Then, not a minute too soon, the rays of the descending sun made their way through an arch on the temple’s western compound wall. The rays passed through a couple of windows into the cave and pierced through the haze of the aarathi.

The beams gradually traversed the length of the Nandi’s body in the direction of his head; and then an hour before sunset, amid the beating of drums, fervent chanting and the pouring of milk libations over the idol, the rays passed through Nandi’s horns and sought the foot of the idol at precisely 5.19pm.

In ten minutes the beams enveloped the idol. Bathed in light, it shone for five whole minutes. Devotees watched their eyes glued to the screen. And then the beams moved away. This annual, ephemeral phenomenon is called Surya Majjana, or the Sun Bath.

For some devout Hindus—apart from being a visual spectacle—this phenomenon is steeped in strong religious symbolism, which explains its draw. But behind it lies a tale of scientific knowledge, architectural prowess and some intriguing local history.

As I had described in an earlier Mint on Sunday article, a unique and crucial characteristic of the earth is the tilt of its axis with its orbital plane. In the absence of this tilt (nearly 23.5 degrees in the present day), the sun would rise and set in the same position every day. And we would have no seasons at all. It this tilt that gives the planet its seasons and a temple in Bengaluru its annual celestial spectacle.

Because the earth rests on its side, so to speak, the points of sunrise and sunset move like a pendulum between the tropics, from one extreme in late December to the other in late June. Correspondingly, the length of the day varies across the world based on the sun’s real-time position.

However, on any given day, somewhere on the planet, the sun is directly overhead at noon. An object on that latitude would have its shadow move exactly on that imaginary latitudinal line from sunrise to sunset; what is more—at local noon, the object could cast no shadow at all. Think of an actor standing on a stage as a spotlight passes directly overhead, in a straight line from one side to the other, pointing straight down.

Now at each hemisphere’s summer solstice, the sun is directly overhead at the respective extreme tropical latitude (~21 June in the northern Tropic of Cancer and ~22 December in the southern Tropic of Capricorn). These are the extremes of the pendulum motion we spoke about before. The sun will go so far and no further to the north or the south. If you live outside these extremes you will never experience the sun directly overhead.

For a person located between the tropics, on the other hand, the sun is overhead at noon twice a year—once when it moves from north to south and once when it goes in the opposite direction. On the tropics, where the sun takes a U-turn so to speak, it happens only once—at the respective solstice. And outside this band, never. This is why “tropical” is a term used to describe places that are very warm at least part of the year.

Cultures all over the world have used observations of winter solstice to keep track of food reserves and agriculture. Many of them even built structures to track this southern extreme point of the sun’s perambulation. The most famous examples include ancient observatories at Stonehenge, Goseck and Chankillo, graves at Newgrange and Maeshowe, the Mayan structures at Tulum and Chichen Itza, and the Karnak Temple complex in Egypt.

Many Hindus believe that different times of the year are suitable for different types of religious worship; auspicious rituals (shubha karya), such as sacred thread ceremonies, are performed by some only during uttarayana (uttara meaning north and ayana meaning motion). Uttarayana (referring to the period of movement of the sun in the northward direction), with its longer, warmer days, signifies a period of positivity for them.

In a similar vein, many believe that dakshinayana (due to shorter periods of daylight) is associated with negative acts. Hence, penitential activities like fasts, fire sacrifices, pilgrimages and charity are undertaken by some during the sun’s movement southwards. The journey of the sun, as it seeks god and cleanses itself after witnessing the debilitating effects of dakshinayana (dakshina meaning south), is a story of redemption strikingly reminiscent of traditional customs.

The festival of Makara Sankranti marks the entry of the sun into the zodiac sign of Makara, or Capricorn. The festival is known by many other names—Pongal, Bihu, Maghi, Maghe Sankranti—in different parts of India and Nepal, and all celebrations include some form of a ritual feast, celebrating the harvest and ceremonially using new items, all signifying new beginnings. At the Gavi Gangadhareshwara temple in Bengaluru, too, this alignment of stars is known as both Makara Sankranti and uttarayana.

This year, Makara Sankranti was celebrated on 14 January. Like the dates of the solstice, it can vary by a day or so in the short term due to Earth’s period of revolution. So currently we live at a time when Sankranti falls on 14 or 15 of January.

But hang on, isn’t there something amiss here?

Recall, uttarayana is the movement of the sun in the northward direction; by definition, shouldn’t it be at the winter solstice, where the sun has reached its apparent southernmost extent? The transition to the northward movement should happen at the end of December, as discussed earlier.

By the middle of January, when the sun moves into Capricorn and Makara Sankranti is celebrated, isn’t the sun in uttarayana already? If so then why is Makara Sankranti confused for uttarayana in the temple’s ceremonies and lore? In fact, there is one more name for the Sankranti festival that I deliberately withheld earlier—it is called Uttarayan in Gujarat and parts of Rajasthan, which lends its name to the kite festival during its celebration.

Over the long term (~25,700 years), the earth wobbles around its axis, slowly changing its orientation (like a wobbly top). This phenomenon is called precession. It causes a gradual shifting of pole stars once every thousands of years.

Similarly, the date of “entry” of the sun entering different zodiac signs also varies—going through a full circle every ~25,700 years, or by 1 degree every ~71.6 years. Makara Sankranti will shift further away from the winter solstice by a day every ~72 years. Amazingly, after about 12,000 years, Makara Sankranti would happen in June, in the peak of northern hemisphere summer, and then move into the dakshinayana realm!

There are other places also where this confusion manifests. The Tropic of Capricorn owes its etymology to the sun entering the constellation of Capricorn (Makara) at the same time of the winter solstice, about 1,700 years ago—also the time when the date of Makara Sankranti exactly matched with that of the winter solstice.

This confusion is quite puzzling given the fact that Indian astronomers were aware of this phenomenon (called ayanamsha) and computed accurate values. The Wikipedia page for Uttarayana notes that lack of understanding of differences between two different existing scales of measurement of a year causes this confusion.

In 2006, a scientist in Bengaluru decided to investigate the matter further.

Vyasa Shastry is a materials engineer and a consultant, who aspires to be a polymath in the future. In his spare time, he writes about science, technology, sport and society. He has contributed to The Hindu (thREAD) and Scroll.