A previously unknown 100–200-metre asteroid — roughly the size of Rome’s Colosseum — has been detected by an international team of European astronomers using the NASA/ESA/CSA James Webb Space Telescope. Their project used data from the calibration of the Mid-InfraRed Instrument (MIRI), in which the team serendipitously detected an interloping asteroid. The object is likely the smallest observed to date by Webb and may be an example of an object measuring under 1 kilometer in length within the main asteroid belt, located between Mars and Jupiter. More observations are needed to better characterize this object’s nature and properties.

The release, images and videos are available on:
https://esawebb.org/news/weic2304/

Kind regards,
ESA/Hubble/Webb Information Centre
6 February 2023