Picture of the month

In this Hubble Space Telescope image, which was released as part of the telescope’s 27th anniversary this year, two very different looking spiral galaxies are visible. The closely neighbouring galaxies – NGC 4302 on the bottom and NGC 4298 on the top – are located next to each other 55 million light-years away and were discovered by astronomer William Herschel in 1784. The galaxies, which are among around 2000 that form the Virgo Cluster, are separated at their closest point by approximately 7000 light-years. Yet despite their close proximity, they apparently lack any significant gravitational interaction. No tidal tails or large deformations, typical for galaxies in close proximity, are observed for this pair, only a faint bridge of neutral hydrogen gas (not visible in the image) appears to stretch between them.

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Compiled by Merlin Kole, Department of Particle Physics, University of Geneva.