Planetary scientists have discovered the first object known to share its orbit with Uranus.

The body, measuring some 60 kilometres in width and dubbed 2011 QF99, stays just ahead of Uranus as the two orbit the Sun. Computer simulations indicate that 2011 QF99 will remain near the planet for around 3 million years.

It is part of a group of outer Solar System bodies in unstable orbits — they become temporarily trapped by giant planets and later return to wandering the Solar System's fringes, report Mike Alexandersen of the University of British Columbia in Vancouver, Canada, and his colleagues.

Science 341, 994–997 (2013)