An Algorithm for Mapping Stars is also Used to Track Whale Sharks

An algorithm that was originally developed to map the stars is also used to track whale sharks for the sake of conservation efforts.

Ahead of the launch of the Hubble Space Telescope in 1990, astronomers needed a way to compare and match star configurations from photos it would capture. So, in 1986 Physics Professor Edward J. Groth invented a pattern matching algorithm to help map galaxies.

The algorithm works by creating a triangle among every possible triplet of stars in an image and then compares the measurement of those triangles to those in other images to find matches.

Whale sharks, whose name in Madagascar is “marokintana” for “many stars,” have distinctive speckles on their backs that look very much like stars in the sky. Each shark is different and each spot is as individual as an individual fingerprint. It is vital for marine biologists that they can track sharks, determine their locations and habits, and match photographs with them. However, manually examining photos of whale sharks was tedious and time-consuming.

In 2002 a software programmer from Portland, Oregon named Jason Holmberg had a rare encounter with a whale shark while scuba diving in the Red Sea. Holmberg was fascinated by these creatures, and became inspired to work with conservationists.

He was aided by Zaven Arzoumanian, a Goddard Space Flight Center astrophysicist who suggested the implementation of an alternative to the Groth algorithm.

Holmberg modified the Groth algorithm to match the spots on the skins of whale sharks. Holmberg was accompanied by Brad Norman, an Australian marine biologist.

Whale Shark Patterns

The idea worked, and the software has been used by marine biologists and conservationists across the planet to record tens of thousands of encounters with whale sharks over the last two decades. It has since been deployed on other types of endangered sharks and giant sea bass that also have distinctive, unique patterns on their skin.

What do whale sharks and stars have in common? @NASAHubble has helped us track both! The algorithm that Hubble uses to identify stars helps us to find individual whale shark spots to aid in tracking them. #WorldOceanDay

— NASA Universe (@NASAUniverse) June 8, 2022

It doesn’t just work on fish either. Researchers can identify individual bears by their distinctive whisker marks.

Image credits: NASA