The technicolor universe, with brightly colored galaxies, appears in the new image made by combining observations from the two most famous space telescopes, Hubble and James Webb. With their lenses on a vast galaxy cluster called MACS0416, 4.3 billion light-years from Earth, they not only obtained one of the most color-rich images ever made, but even discovered 14 new celestial objects whose brightness varies over time.
Cluster MACS0416 is composed of two galaxies on a collision course that will then merge to form an even larger cluster. The images show an astonishing amount of detail, revealed thanks to the combination of visible and infrared observations by Hubble (by NASA and the European Space Agency) and Webb (operated by the space agencies of the United States, Europe and Canada). Also striking is the abundance of galaxies outside the cluster and the presence of some sources that vary over time, probably due to the gravitational lensing effect generated by the distortion and amplification of light from distant sources in the background.
To make the composite image, the shorter wavelengths were coded with the color blue, the longer wavelengths with red, and the intermediate wavelengths with green. In this way, the wide wavelength range (from 0.4 to 5 microns) produces a particularly vivid landscape of galaxies.
These colors provide clues to the distances of galaxies: bluest galaxies are relatively close and often show intense star formation, as best detected by Hubble, while redder galaxies tend to be more distant and are better detected by Webb. Some galaxies also appear very red because they contain copious amounts of cosmic dust that tends to absorb the bluest colors of starlight.
Thanks to these observations, it was also possible to identify 14 objects that showed a time-varying brightness: 12 are probably stars or multi-stellar systems, while the other two could be supernovae. Among the most interesting objects is a star system called Mothra, along with another previously identified star nicknamed Godzilla.
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