The NASA/ESA Hubble Space Telescope — with a little help from an amateur astronomer — has produced one of the best views yet of nearby galaxy Messier 106, a striking spiral galaxy with a number of secrets.

Located a little over 20 million light-years away, practically a neighbor by galactic standards, Messier 106 is one of the brightest and nearest spiral galaxies to our Milky Way. Although it may not look particularly unique, some of its features have baffled astronomers for years.

Messier 106 has a supermassive black hole at its centre. Although this is true for most galaxies, this black hole is particularly active and hungry, gobbling up nearby material at a startling rate.

This huge black hole’s bottomless appetite is behind much of the galaxy’s unusual behavior. Messier 106 appears to be emitting powerful radiation from its centre — something we do not see with our Milky Way or other similar spirals. This is caused by the very active black hole at the galaxy’s centre, which violently drags gas and dust inwards. This material heats up, emitting bright microwave and X-ray radiation as it does so.
However, this emission is not the most intriguing feature of this spiral galaxy. This image shows the galaxy’s other not-so-hidden secret — alongside its two regular star-packed spiral arms, it appears to have two more, made of hot, glowing gas. While these extra arms have been known about for decades, astronomers were unsure of how they formed — until recently.