CUTTING EDGE
Weighing the Kuiper Belt
The measurement was made with an unusual instrument – the Cassini spacecraft observing Saturn
Far away in the gloomy, distant suburbs of the outer Solar System, beyond the orbit of Neptune, lies a whole swarm of small, icy bodies. These trans-Neptunian objects (TNOs) mostly orbit at a distance of between about 30 and 50 astronomical units (AU) from the Sun – where 1 AU is the distance between the Sun and Earth. They make up the Kuiper Belt, a diffuse disc some 20 times wider than the asteroid belt and around 100 times more massive.
As more and more TNOs have been discovered, something very strange has been noticed; one group of
