SPHEREx's Dust Cloud Reveal
In April 2025, just weeks after its launch, NASA's SPHEREx mission revealed a cloud of dust in a patch of sky inside the Large Magellanic Cloud, a dwarf galaxy near the Milky Way, when making observations in a specific infrared wavelength (3.29 microns).
Figure A shows the same section of sky observed by SPHEREx (Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer) in a different infrared wavelength (0.98 microns) – and the dust cloud is invisible. That's because the cloud is composed of molecules called polycyclic aromatic hydrocarbons, which have a consistency similar to soot. These molecules radiate light at a few specific wavelengths but not others.
The difference between the images illustrates the power of multiwavelength observations for revealing hidden features of the universe – a key feature of SPHEREx.
Observing individual wavelengths of light from cosmic sources is called spectroscopy. This technique can be used to reveal the composition of objects, because chemical elements and molecules leave a unique signature in the colors they absorb and emit. Spectroscopy can also help scientists measure how far away galaxies are, making it essential for SPHEREx's goal of mapping the locations of hundreds of millions of galaxies in 3D.
SPHEREx detects infrared light, which is invisible to the human eye, but is represented here in visible colors. The observatory will map the entire sky in 102 infrared colors (or wavelengths of light) to learn more about our universe. To do this, the mission images every object in the sky 102 times, each in a different wavelength. The spacecraft will map the entire sky four times over two years.
The SPHEREx mission is managed by NASA's Jet Propulsion Laboratory for the agency's Astrophysics Division within the Science Mission Directorate at NASA Headquarters. BAE Systems in Boulder, Colorado, built the telescope and the spacecraft bus. The science analysis of the SPHEREx data will be conducted by a team of scientists located at 10 institutions in the U.S., two in South Korea, and one in Taiwan. Caltech in Pasadena managed and integrated the instrument. The mission's principal investigator is based at Caltech with a joint JPL appointment. Data will be processed and archived at IPAC at Caltech. The SPHEREx dataset will be publicly available at the NASA-IPAC Infrared Science Archive. Caltech manages JPL for NASA.
For more about SPHEREx, visit: