SPHEREx Scans the Sky

This video shows the SPHEREx observatory's field of view as it scans across a section of the sky, observing the universe in 102 colors, or wavelengths of light. Taken in April 2025, just weeks after the spacecraft's launch, the images show a region inside the Large Magellanic Cloud, a dwarf galaxy near the Milky Way. The wavelengths seen by NASA's SPHEREx (Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer) are in the infrared range, which is invisible to the human eye; the infrared wavelengths are represented here by visible light colors. While most telescopes use color filters that block one wavelength at a time, SPHEREx's filters gradually transition through a range of wavelengths, creating the rainbow gradients seen in this video. The telescope takes overlapping images so that every section of the sky is imaged 102 times, each time in a different wavelength. The color filters sit on top of two arrays, each with three detectors, that observe the sky simultaneously. In the video, one array's view moves from purple to green, followed by the second array's view (of the same section of sky), which changes from yellow to red. The images are looped four times. SPHEREx will repeat this scanning motion each day for two years, gradually compiling a map of the entire sky. Every day, it will take about 600 exposures, each of which is made up of six images, one from each of the six detectors. Combining those images, scientists can see the total emission from the observed section of the sky or look at an individual wavelength. 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. This is made apparent in the images' lower right quadrant, where a collection of dust appears only in the red and orange wavelengths. This indicates the presence of a particular molecule that radiates in specific wavelengths and not others. Video available at https://photojournal.jpl.nasa.gov/catalog/PIA26351