JWST Has Accidentally Detected a Tiny Asteroid 'Hidden' Between Mars And Jupiter

Failed JWST observations of a particular target have produced something far more fascinating.

A previously undiscovered, very small asteroid was discovered by the space telescope in the belt of asteroids that travels between Mars and Jupiter. The still-unnamed rock fragment is most likely the tiniest object the JWST has yet discovered. It is just 100 to 200 meters (328 to 656 feet) broad.

It not only serves as a stunning illustration of the JWST's capabilities, but it also raises the possibility of using those capabilities to more accurately classify the millions of bits of debris that lie in the Main Belt.

According to astronomer Thomas Müller of the Max Planck Institute for Extraterrestrial Physics in Germany, "We - entirely unexpectedly - discovered a tiny asteroid in publicly accessible MIRI calibration measurements."

"Our work predicts that numerous new objects will be found with this device," the researchers write. "The results represent some of the first MIRI measurements targeting the ecliptic plane."

Scientists started putting the JWST through its paces, calibrating its instruments, and ensuring sure everything was working as it should when it figuratively opened up its golden honeycomb eye in July 2022. The Mid-Infrared Instrument, or MIRI, is one of those tools.

The Main Belt's considerably bigger asteroid (10920) 1998 BC1, which is 15.7 kilometers (9.75 miles) diameter and was identified in 1998, served as MIRI's calibration target. Unfortunately, the JWST observations were not very successful since the telescope wasn't exactly pointed straight forward and the target pictures were blown out and very bright.

The JWST photos, together with information from other ground- and space-based observatories, allowed the researchers to test several strategies for restricting the size and orbit of asteroids, so it wasn't a total loss for 10920.

However, there was also another thing. A dim object that moved in relation to 10920 and the background light sources was visible in each photograph. The researchers conducted a thorough investigation and concluded that the dim object was most likely a different, smaller, previously undiscovered asteroid.

The finding has not yet been verified, but if it is, it will rank among the Main Belt's tiniest asteroids ever found. For investigations of the size-frequency distribution of objects in the belt, finding asteroids of this size is crucial.

Finding asteroids in an asteroid belt may seem like a simple task, but it's actually a lot more difficult than you may imagine. Over 600,000 Main Belt asteroids have been positively identified by astronomers so far, and over 550,000 more have been provisionally recognized. However, it is anticipated that there are millions and millions more of them, the most of which are minuscule in size.

Additionally, smaller ones are far more difficult to find than bigger ones. Which makes finding one by mistake somewhat of a coup.

If you have the appropriate attitude and a little bit of luck, even "failed" Webb observations may be scientifically valuable, according to Müller's findings.

Although the object was within the main asteroid belt, Webb's extraordinary sensitivity allowed it to be seen at a distance of more than 100 million kilometers.

The asteroid belt, which spans a distance of between 2.2 and 3.2 astronomical units from the Sun, or 329 million to 478.7 million kilometers, or 204.43 million to 297.45 million miles, is a sparsely populated doughnut of asteroids that hangs out on the plane of the Solar System.

However, it is thought that asteroids are typically 965,600 kilometers apart. You might not see anything at all unless you're focusing on the proper area of the sky.

During its calibration observations, the JWST unintentionally saw the correct area of the sky. As it monitors targets that are in alignment with the plane of the Solar System, the researchers think it may have more of these fortunate encounters in the future.

We expect that MIRI frames with pointings near the ecliptic and brief integration durations of barely a few seconds will always contain a few asteroids, the majority of which will be unidentified objects.

The research has been published in Astronomy & Astrophysics.