Science Alert reports:

If you travel far enough away from the Sun, the Solar System becomes a lot more populated.

Out past the orbit of Neptune lies the Kuiper Belt, a vast, ring-shaped field of icy rocks. This is where Pluto resides, and Arrokoth, and countless other small objects in the cold and the dark.

These are known as Kuiper Belt objects or KBOs, and astronomers have just found hints of an unexpected rise in their density, between 70 and 90 astronomical units from the Sun, separated by a large, practically empty gap between it and an inner population of KBOs closer to the Sun.

It seems, almost, like there are two Kuiper Belts, or at least two components – something nobody was expecting to find.

“If this is confirmed, it would be a major discovery,” says planetary scientist Fumi Yoshida of the University of Occupational and Environmental Health Sciences and Chiba Institute of Technology in Japan.

“The primordial solar nebula was much larger than previously thought, and this may have implications for studying the planet formation process in our Solar System.”

The objects in the Kuiper Belt are thought to represent the most pristine material our Solar System contains.

The belt itself extends from the orbit of Neptune, around 30 astronomical units from the Sun (an astronomical unit is the average distance between Earth and the Sun), out to about 50 astronomical units from the Sun.

This distance from the Sun means that anything within the Kuiper Belt is only minimally affected by solar radiation, which, in turn, means that KBOs likely remain pretty much unchanged since the Solar System was born, some 4.6 billion years ago. [Continue reading…]