The interacting galaxy pair NGC 5394/5 was first observed by William Herschel in 1787 using his 20-foot-long telescope. Since then, the galaxies, also known collectively as the Heron Galaxy thanks to their gravitationally distorted appearance, have become familiar targets for amateurs and professionals alike. This spectacular view was captured by the Gemini North 8-metre telescope in Hawaii using the Gemini Multi-Object Spectrograph. The four-colour composite image is the result of a 42-minute exposure. Astronomers believe the two galaxies have collided at least once before and are still engaged in a gravitational tug-of-war that will take millions of years to play out. Galactic collisions trigger star formation, visible in this image as reddish concentrations scattered throughout the larger galaxy (NGC 5395) and in the extended arms of the smaller companion (NGC 5394). Also known as Arp 84, the galaxy pair is located some 160 million light years from Earth in the constellation Canes Venatici.
A 42-minute exposure of the interacting galaxy pair NGC 5394/5 captured by the National Optical-Infrared Astronomy Research Laboratory’s Gemini North 8-metre telescope using the Gemini Multi-Object Spectrograph in imaging mode. Image: National Optical-Infrared Astronomy Research Laboratory/Gemini Observatory/AURA