Free Astronomy Magazine May-June 2023

MAY-JUNE 2023 is likely the smallest observed to date by Webb and may be an exam- ple of an object measuring under 0.6 miles (1 kilometer) in length within the main asteroid belt, lo- cated between Mars and Jupiter. More observations are needed to better characterize this object’s na- ture and properties. “We — completely unexpectedly — detected a small asteroid in publicly available MIRI calibration observa- tions,” explained Thomas Müller, an astronomer at the Max Planck Institute for Extraterrestrial Physics in Germany. “The measurements are some of the first MIRI measure- ments targeting the ecliptic plane and our work suggests that many new objects will be detected with this instrument.” These Webb observations, pub- lished in the journal Astronomy and Astrophysics , were not de- Webb detects extremely small main belt asteroid by NASA/ESA/CSA Bethany Downer Christine Pulliam A n asteroid roughly the size of Rome’s Colosseum — be- tween 300 to 650 feet (100 to 200 meters) in length — has been detected by an international team of European astronomers using NASA’s James Webb Space Telescope. Their project used data from the calibration of the Mid-In- fraRed Instrument (MIRI), in which the team serendipitously detected an interloping asteroid. The object A rtwork: NASA, ESA, CSA, N. Bartmann (ESA/Webb), Martin Kornmesser (ESA), Serge Brunier (ESO), Nick Risinger (Photopic Sky Survey)