Astronomers have detected a 1.3 km radius body at the edge of the Solar System. ‘Edgeworth-Kuiper Belt Objects’ with radii from 1 km to several kilometers have been predicted to exist for more than 70 years. These objects acted as an important step in the planet formation process.
A research team led by Ko Arimatsu at the National Astronomical Observatory of Japan used a technique known as occultation: monitoring a large number of stars and watching for the shadow of an object passing in front of one of the stars. The team monitored approximately 2000 stars for a total of 60 hours.
Analyzing the data, the team found an event consistent with a star appearing to dim as it is occulted by a 1.3 km radius Edgeworth-Kuiper Belt Object. This detection indicates that there are numerous Edgeworth-Kuiper Belt Objects. This supports models where planetesimals first grow slowly into kilometer sized objects before runaway growth causes them to merge into planets.