The universe in artistic color in Hubble and Webb images

The colorful universe, with brightly colored galaxies, appears in the new image created by combining observations from the two most famous space telescopes, Hubble and James Webb. Focusing their targets on a wide cluster of galaxies called MACS0416, 4.3 billion light-years from Earth, they allowed not only to obtain one of the most colorful images ever, but also to discover 14 new celestial objects whose brightness changes over time.

The MACS0416 cluster consists of two galaxies on a collision course that then merge to form a larger cluster. The images show a surprising amount of detail, revealed thanks to a combination of visible and infrared observations from Hubble (NASA and ESA) and WEB (operated by space agencies in the US, Europe and Canada). Also striking is the abundance of galaxies outside the cluster and the presence of some sources that vary with time, perhaps due to the effect of gravitational lensing resulting from the distortion and amplification of light from distant background sources.

To create the composite image, shorter wavelengths are coded in blue, longer wavelengths in red, and intermediate wavelengths in green. In this way, a wide wavelength range (0.4 to 5 microns) produces a particularly vivid galactic scene.

These colors provide clues to the distances between galaxies: bluer galaxies are relatively close and often show intense star formation, which is best detected by Hubble, while redder galaxies tend to be more distant and are best detected by Webb. Some galaxies also appear very red because they contain abundant amounts of cosmic dust, which tends to absorb the blue hues of starlight.

Thanks to these observations, it was also possible to identify 14 objects that showed time-varying brightness: 12 of them were likely stars or multi-star systems, while the other two could be supernovas. Among the most interesting, a star system called Mothra stands out, along with another previously identified star nicknamed Godzilla.