The Hubble Space Telescope and the James Webb Space Telescope are both powerful tools for peering out into the cosmos, but the way they view the universe is quite different. While Hubble primarily looks in the visible light wavelength in the same range as the human eye, Webb looks in the infrared range which is beyond human vision. Looking at the same object in different wavelengths reveals different features, as a recently released pair of image demonstrates.
Webb and Hubble both imaged the spiral galaxy IC 5332, located over 29 million light-years away. Though this galaxy is only about one-third of the size of the Milky Way, it makes a great target for astronomy because the spiral is almost perfectly face-on from our point of view. The image captured by Webb’s ultra-cool MIRI instrument shows the skeletal-like structure of the galaxy’s spiral arms.
Compare this image to an image taken by Hubble, which shows dust as dark patches blocking out light through the spiral arms.
On the ESA Webb website there is a slider which lets you compare the two images directly and see the similarities and differences that they observe when looking at the same galaxy.
The reason the galaxy looks so different in visible light versus infrared is to do with the dust spread throughout it, as the European Space Agency explains: “Ultraviolet and visible light are far more prone to being scattered by interstellar dust than infrared light. Therefore dusty regions can be identified easily in the Hubble image as the darker regions that much of the galaxy’s ultraviolet and visible light has not been able to travel through. Those same dusty regions are no longer dark in the Webb image, however, as the mid-infrared light from the galaxy has been able to pass through them.”
