As scientists calibrated the Webb Telescope’s Mid-Infrared Instrument, it “serendipitously” captured a small passing asteroid with great detail, surprising observers.
The asteroid is said to be the size of Rome’s Coliseum, with a width of about 300 to 650 feet. The object was found orbiting in the solar system’s main asteroid belt, which goes between Mars and Jupiter.
“We — completely unexpectedly — detected a small asteroid in publicly available MIRI calibration observations,” said Thomas Müller, an astronomer at the Max Planck Institute for Extraterrestrial Physics. “The measurements are some of the first MIRI measurements targeting the ecliptic plane and our work suggests that many new objects will be detected with this instrument.”
The Webb Telescope was not originally designed to spot new asteroids. They attempted to image main belt asteroid (10920) 1998 BC1, which is much larger. But the telescope’s instrument failed to capture the object due to its brightness. Yet, through the failure, scientists captured something even more stunning.
“Our results show that even ‘failed’ Webb observations can be scientifically useful, if you have the right mindset and a little bit of luck,” said Müller. “Our detection lies in the main asteroid belt, but Webb’s incredible sensitivity made it possible to see this roughly 100-meter object at a distance of more than 100 million kilometers.”
It is believed to be the smallest object captured by the telescope. But the asteroid’s discovery has given scientists hope that the Webb Space Telescope can now be a tool to them find other small asteroids.
They believe pointing the telescope toward the ecliptic plane would frequently turn up new asteroids.
“This is a fantastic result which highlights the capabilities of MIRI to serendipitously detect a previously undetectable size of asteroid in the main belt,” concluded Bryan Holler, Webb support scientist at the Space Telescope Science Institute. “Repeats of these observations are in the process of being scheduled, and we are fully expecting new asteroid interlopers in those images.”