Reanalysis of Webb data discovers more than a hundred very small main-belt asteroids

Portrait of all 138 new asteroids
Click for original image.

Using data from the Webb Space Telescope in an unexpected way, astronomers have discovered 138 asteroids in the main asteroid belt, most of which are the smallest so far detected.

The picture to the right shows all 138 asteroids. The researchers had originally used Webb to study the atmospheres of the exoplanets that orbit the star TRAPPIST-1. They then thought, why not see if their data also showed the existence of asteroids in our own solar system. By blinking between multiple images they might spot the movement of solar system objects moving across the field of view. From the press release:

The team applied this approach to more than 10 000 [Webb] images of the TRAPPIST-1 field, which were originally obtained to search for signs of atmospheres around the system’s inner planets. By chance TRAPPIST-1 is located right on the ecliptic, the plane of the solar system where all planets and most asteroids lie and orbit around the Sun. After processing the images, the researchers were able to spot eight known asteroids in the main belt. They then looked further and discovered 138 new asteroids, all within tens of meters in diameter — the smallest main belt asteroids detected to date. They suspect a few asteroids are on their way to becoming near-Earth objects, while one is likely a Trojan — an asteroid that trails Jupiter.

The data is insufficient for most of these objects to chart their orbits precisely. Based on this one single study, however, it suggests that pointing Webb along the ecliptic in almost any direction will detect more such objects. Do this enough and astronomers might actually be able to get a rough census of the asteroid belt’s population.

New theory for formation of main asteroid belt

The uncertainty of science: Using computer models, astronomers have developed a new completely different theory to explain the existence of the asteroid belt between Mars and Jupiter.

The asteroid belt (sometimes referred to as the main asteroid belt) orbits between Mars and Jupiter. It consists of asteroids and minor planets forming a disk around the sun. It also serves as a sort of dividing line between the inner rocky planets and outer gas giants. Current theory suggests that the asteroid belt was once much more heavily populated, but the gravitational pull of Jupiter flung approximately 99 percent of its former material to other parts of the solar system or beyond. Astronomers also assumed that Jupiter’s gravity prevented the material in the belt from coalescing into larger planets. In this new effort, the researchers propose a completely different explanation of the asteroid belt’s origin—suggesting that the belt started out as an empty space and was subsequently filled by material flung from the inner and outer planets.

The new theory is interesting in that it really illustrates how little we really know about the formation of our solar system. The simple fact is that either one of these theories might be the answer, even though they propose completely opposite initial conditions. We simply do not have enough information about solar system formation in general to constrain our models and determine which of these theories is right.

Until scientists have been able to study hundreds, if not thousands, of solar systems up close, these models will be nothing more than interesting exercises in computer modeling.