At the edge of the Solar System, there appears to be an abundance of interplanetary dust: what does this mean

New Horizons, a NASA probe launched to explore the outer reaches of the solar system, has discovered an unusually high concentration of interplanetary dust in a remote area of the Kuiper Belt. This indicates that its extent is much greater than previously thought.

This was reported by SSPDaily.

The Kuiper Belt begins in Neptune's orbit, at a distance of approximately 30 AU (an AU is the average distance from the Earth to the Sun, i.e., 140 million kilometers), and extends for an unknown distance. It contains a huge number of rocky icy objects, including large asteroids and dwarf planets. Scientists cannot yet observe them because they are relatively small to reflect enough sunlight.

In 2015, New Horizons flew past Pluto, which orbits at a distance of 39 AU from the Sun, and continued to collect data. In January 2019, it reached the mysterious Arrocathus object, which orbits the Sun at an average distance of 44.6 AU.

At a distance of 45-55 AU, the probe recorded a much higher amount of interplanetary dust than expected. This suggests that either new dust is forming here or the Sun's radiation is pushing it out of denser areas.

The most likely source of additional dust could be interactions between larger objects, such as collisions. This implies that there must be enough icy rocks around for them to collide with each other relatively frequently.

"New Horizons is making the first direct measurements of interplanetary dust far beyond Neptune and Pluto, so every observation could lead to a discovery. The idea that we could detect an extended Kuiper Belt - with an entirely new population of objects colliding and producing more dust - offers another key to unlocking the mysteries of the solar system's most distant regions," said physicist Alex Doner of the University of Colorado at Boulder.