NGC 5042 is a breathtaking spiral galaxy showcasing a brilliant mix of ancient stars, young blue clusters, and vibrant pink H II regions—stellar nurseries illuminated by massive, short-lived stars.

This stunning spiral galaxy, NGC 5042, is the focus of this Hubble Space Telescope Picture of the Week. Located about 48 million light-years away in the constellation Hydra (the Water Snake), NGC 5042 dominates the frame of this Hubble image. A single foreground star from our Milky Way, marked by cross-shaped diffraction spikes, appears near the galaxy’s edge, blending in with its bright stellar surroundings.

To create this vibrant image, Hubble observed NGC 5042 in six different wavelengths, ranging from ultraviolet to infrared. The galaxy’s core glows with a warm, cream-colored light, a sign of densely packed ancient stars. In contrast, its spiral arms sparkle with young blue stars, scattered in luminous clusters. Beyond NGC 5042, faint elongated yellow-orange shapes reveal even more distant background galaxies, adding depth to this cosmic scene.

Perhaps NGC 5042’s most striking feature is its collection of brilliant pink gas clouds that are studded throughout its spiral arms. These flashy clouds are called H II (pronounced “H-two”) regions, and they get their distinctive colour from hydrogen atoms that have been ionised by ultraviolet light. If you look closely at this image, you’ll see that many of these reddish clouds are associated with clumps of blue stars, often appearing to form a shell around the stars.

H II regions arise in expansive clouds of hydrogen gas, and only hot and massive stars produce enough high-energy light to create an H II region. Because the stars capable of creating H II regions only live for a few million years — just a blink of an eye in galactic terms — this image represents a fleeting snapshot of life in this galaxy.