The world is currently in the grips of an artificial intelligence (AI) frenzy. Everyone is trying ChatGPT, AI stocks are surging T to record highs and people are worried about whether machines are coming for their jobs. Yet astronomers have been using similar techniques to unlock the universe’s secrets for decades. “It goes back over 30 years,” says Chris Impey from the University of Arizona. In 1990, Impey’s colleagues at the university’s Steward Observatory used an artificial neural network (ANN) to both divide galaxies into groups based on their appearance and to distinguish between stars and galaxies in images of the sky. An ANN is fed a series of training images and is then set free to analyse new data. It looks for connections between data points and is based on a simplified version of the human brain.
Classifying galaxies is intricate work. “Humans can’t do it well enough,” Impey says. Deciding whether a galaxy is a spiral or an elliptical may be fairly straightforward, but smaller details can be crucial. The galaxy may or may not have a bar structure in the centre, be asymmetrical or have distortions close to its outer edge. “That might
