Shinshumara is the mysterious constellation which hosts the drifting celestial north pole. Several Purana texts make a reference to it. However, these references can not be anything but symbolic. We must refer to the texts of Vedic astronomers to get a clue. Only then can we understand what this constellation corresponds to in a physical sense. Let us look at the Dhruva-Matsya asterism in this regard.
Presently, the celestial north pole is near the tip of the tail segment of the Ursa-Minor asterism. In fact, many call the star at this location as Polaris. Secondly, this asterism has seven stars. We can not but notice five of them forming an arc. Is this arc a part of the Dhruva-Matsya asterism? Firstly, Dhruva-Matsya means the fish. Secondly, it is in the vicinity of Dhruva, the celestial north pole. Thirdly, Hindu astronomers in the past have used it as a celestial clock.
Twelve stars form the Dhruva-Matsya asterism. However, experts today are unable to tell us more about these twelve stars. Sadly, Indians have stopped learning about their own astronomical heritage. We therefore have to refer to old Sanskrit manuscripts and writings from 600-1000 years ago for clues.
Let us start with an invention from 1425 CE. A less Known astronomer made a simple and versatile instrument for sky measurements. Artisans likely made a last replica of this instrument around 1870s. Consequently, most of these replicas landed up in Europe. Certainly, the Oxford museum has one of these replicas. Therefore, a curious researcher must turn to a copy of the writings of the inventor. The inventor Padmanabha’s instrument relies on Dhruva-Matsya. Astronomer Padmanabha refers to the relative distance of the celestial north pole from two key stars in the Dhruva-Matsya fish. We do not get any other clues from his texts we have to locate the stars which appear like a fish.
Searching for more clues
We get our second clue from the text of the more famous astronomer, Bhaskaracharya. He refers to the position of the Sun when the fish is in a horizontal position. Secondly, he says that the star at the mouth of the fish is closer to the Sun’s position than the star at the tail. Therefore, we get more confidence in the idea that the arc of Ursa Minor is indeed a part of the fish. However, the relative positions of the stars at the mouth and the tail of the fish do not fit Padmanabha’s notes. Let us understand a bit about this.
The position of the celestial pole star drifts over centuries. Certainly, this drift explains the mismatch. Secondly, the celestial pole star has drifted from the time of Bhaskaracharya to the time of Padmanabha. Fortunately, we have access to sophisticated astronomy software now. This software helps us roll back to the time of these two Indian astronomers. Thereby we get a comforting assessment. We can also roll the date further back to 540 CE, to the time of Aryabhata, the astronomer genius. Consequentially we understand the reason for associating the fish figure after Dhruva.
The north pole has shifted along the lower arc of the Dhruva-matsya fish figure. Certainly, we have the right assessment of the location of the Dhruva Matsya. How about the symbolism of the Shinshumara? The Gangetic Dolphin or the porpoise is known as Shinshumara in Sanskrit. We have to continue to seek clues about its sky counterpart for now.