New Scientist: A group of icy objects in the outer solar system appear years younger than their suspected age--1 billion years old.

The largest member of the family, called 2003 EL61, was discovered in 2005. In 2007, astronomers found five smaller objects travelling in similar orbits. Their paths suggested they all formed a single object that was broken apart in a collision more than a billion years ago.

A team led by David Rabinowitz of Yale University in New Haven, Connecticut, US, have released a paper on Arxiv that the brightness of the large object and four of the smaller ones (the fifth could not be observed) changes little when observed from various points along Earth's orbit. That suggests their surfaces are covered with fresh powdery ice no more than 100 million years old.