This image, taken by NASA/ESA’s Hubble Space Telescope, shows JO204, a “jellyfish galaxy” named after bright gas branches lazily drifting beneath JO204’s bright central mass. The galaxy is located about 600 million light-years from us, in the constellation Sextans. Hubble observed JO204 as part of a study designed to better understand star formation under extreme conditions.

While the delicate gas lanes beneath JO204 may look like the floating tentacles of a jellyfish, they are actually the result of an intense astronomical process known as pressure stripping. Rotational pressure is a special type of pressure exerted on a body when it moves relative to a fluid. An intuitive example is the feeling of pressure you feel when standing in a strong wind; Wind is a moving fluid and your body feels the pressure from it.

An extension of this analogy is that your body will remain intact and whole, but looser things like hair and clothing will fly in the wind. The same goes for jellyfish galaxies. They experience sharp pressure due to their movement against the intergalactic medium, which fills the space between galaxies in the galaxy cluster. Galaxies are subjected to intense pressure from this movement, and as a result, their more loosely bound gases are ejected.

This gas is mostly the colder, denser gas in the galaxy—gas that, when mixed and compressed under intense pressure, collapses to form new stars in the beautiful branches of the jellyfish.