A study that is yet to be published but reported by Science has detailed an argument for something beyond the Kuiper Belt that has since gone unnoticed, or the Kuiper Belt is far larger than researchers have previously measured.
The current understanding of the Kuiper Belt is that it extends from the orbit of Neptune at 30 astronomical units and is 50 astronomical units away from the Sun. One astronomical unit (AU) is the distance between Earth and the Sun. This circumstellar disc in the outer solar system is essentially a cosmic donut that is made up of icy objects that are all orbiting the Sun. Beyond 50 astronomical units, researchers generally believe there are no more objects.
However, according to the new study, researchers looked at the sensors aboard NASA's New Horizons spacecraft, which is currently at a distance of 57 AU - far beyond the Kuiper Belt. These sensors are designed to detect levels of dust, which is used as an indicator for being close to an object. According to the team, New Horizon sensors are reporting an increasing level of dust, suggesting that something is beyond the outer perimeter of the Kuiper Belt.
"The number of impacts is not declining. And the simplest explanation for that is that there is more stuff out there that we haven't detected," said Alan Stern, principal investigator of the New Horizons mission and a planetary scientist at the Southwest Research Institute.
"Why are we not seeing these things? Did everyone get unlucky? It's possible, but it's hard," said Pedro Bernardinelli, an astronomer at the University of Washington who was not involved in the research.
"Is there a larger population beyond 60 AU? There could be. Maybe that's what we're seeing. I'm not sure," said Hilke Sclichting, an astrophysicist at the University of California, Los Angeles