Close-up: Spiral Galaxy NGC 3596 in Leo | Hubble

Close-up: Spiral Galaxy NGC 3596 in Leo | Hubble

The spiral galaxy NGC 3596 is on display in this NASA/European Space Agency Hubble Space Telescope picture that incorporates six different wavelengths of light. NGC 3596 is situated 90 million light-years from Earth in the constellation Leo. The galaxy was discovered in 1784 by astronomer William Herschel, the namesake of the European Space Agency’s Herschel Space Observatory. 

NGC 3596 appears almost perfectly face-on when viewed from Earth, showcasing the galaxy’s neatly wound spiral arms. The bright arms mark where the galaxy’s stars, gas and dust are concentrated. Star formation is also most active in a galaxy’s spiral arms, as shown by the brilliant pink star-forming regions and young blue stars tracing NGC 3596’s arms in this image.

What causes these spiral arms to form? It’s a surprisingly difficult question to answer, partly because of the remarkable diversity of spiral galaxies. Many have clear spiral arms, while others have patchy, feathery arms. Many have prominent bars across their centers, while others have compact, circular nuclei. Many have close neighbors, while others are isolated.

Early ideas of how spiral arms formed were stumped by what is called the ‘winding problem’. If a galaxy’s spiral arms are coherent structures, the arms would be wound tighter and tighter as the galaxy spins, until the arms are no longer visible. Now, researchers believe that spiral arms represent a pattern of high-density and low-density areas rather than a physical structure. As stars, gas and dust orbit within a galaxy’s disc, they pass in and out of the spiral arms. Much like cars moving through a traffic jam, these materials slow down and bunch up as they enter a spiral arm, before emerging and continuing their journey through the galaxy.

Image Description: A spiral galaxy viewed face-on, with a slightly oval-shaped disc. The center is a bright white spot surrounded by a golden glow. Two spiral arms extend out from the center, wrapping around the galaxy and broadening out to form the thick outer edge of the disc. Thin reddish strands of dust and bright pink spots follow the arms through the disc. Faint strands of stars extend from the arms’ tips, out beyond the disc.

Credit: ESA/Hubble & NASA, D. Thilker

Duration: 30 seconds
Release Date: May 5, 2025

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