MIRI and Spitzer Comparison Image

The NASA/ESA/CSA James Webb Space Telescope is aligned across all four of its science instruments. Here we take a closer look at Webb’s coldest instrument: the Mid-Infrared Instrument, or MIRI.

This MIRI test image (at 7.7 microns) shows part of the Large Magellanic Cloud. This small satellite galaxy of the Milky Way provided a dense star field to test Webb’s performance.

Here, a close-up of the MIRI image is compared to a past image of the same target taken with NASA’s Spitzer Space Telescope’s Infrared Array Camera (at 8.0 microns). The retired Spitzer was the first observatory to provide high-resolution images of the near- and mid-infrared Universe. Webb, by virtue of its significantly larger primary mirror and improved detectors, will allow us to see the infrared sky with improved clarity, enabling even more discoveries.

For example, Webb’s MIRI image shows the interstellar gas in unprecedented detail. Here, you can see the emission from ‘polycyclic aromatic hydrocarbons’ – molecules of carbon and hydrogen that play an important role in the thermal balance and chemistry of interstellar gas. When Webb is ready to begin science observations, studies such as these with MIRI will help give astronomers new insights into the birth of stars and protoplanetary systems.