Five days before the completion of the Spitzer mission, scientists used the spacecraft's infrared camera to take several pictures of the California nebula.
The California Nebula is a pretty memorable target considering mission control and scientific operations were founded at NASA's Jet Propulsion Laboratory in Southern California and California Institute of Technology. This is Spitzer's latest mosaic image and one of hundreds captured by the space telescope throughout its work.
It is located about 1000 light-years from Earth and looks more than a little like the state of the same name when viewed with visible light telescopes: it is long and narrow, curving to the right at the bottom. Visible light comes from gas in the nebula heated by the nearby extremely massive star Xi Perseus or Menkib. Infrared images from Spitzer reveal another feature: warm dust, similar in consistency to soot, that mixes with the gas. The dust absorbs visible and ultraviolet light from nearby stars and then re-emits the absorbed energy as infrared light.
From 2009 to 2020, Spitzer used 2 detectors that simultaneously displayed adjacent areas of the sky. The detectors captured infrared waves of various lengths: 3.6 micrometers (shown on the left) and 4.5 micrometers (shown on the right). Different wavelengths of light can reveal different objects or features. Spitzer scanned the sky, taking multiple shots in a grid so that both detectors would display an area in the center of the grid. By superimposing these images on top of each other, you can see how a given region looks at several wavelengths, like in the central part of the image.
During the last week of the telescope's operation, the research team selected a target from a list of potential targets that would be in Spitzer's field of vision. The California nebula, which had not previously been studied by Spitzer, stood out due to its likelihood of containing noticeable infrared features and could potentially be useful to study.