Hubble time! 🌌 The dwarf irregular galaxy NGC 5238, located 14.5 million light-years from Earth in the constellation Canes Venatici is theorised to have recently — here meaning no more than a billion years ago! — had a close encounter with another galaxy. The evidence for this is the tidal distortions of NGC 5238’s shape, the kind produced by two galaxies pulling on each other as they interact. There’s no nearby galaxy which could have caused this disturbance, so the hypothesis is that the culprit is a smaller satellite galaxy that was devoured by NGC 5238. Traces of the erstwhile galaxy might be found by closely examining the population of stars in NGC 5238. Two tell-tale signs would be groups of stars with properties that look out of place compared to most of the galaxy’s other stars, indicating that they were originally formed in a separate galaxy, or stars that look to have all formed abruptly at around the same time, which would occur during a galactic merger. The data used to m...