NASA's Dawn spacecraft has arrived in orbit around Ceres, the largest dwarf planet in the asteroid belt.
The space agency said that the craft was now officially in lockstep with the strange world, at a distance of around 38,000 miles from the surface.
"Since its discovery in 1801, Ceres was known as a planet, then an asteroid and later a dwarf planet," said Marc Rayman, Dawn chief engineer and mission director at JPL. "Now, after a journey of 3.1 billion miles (4.9 billion kilometers) and 7.5 years, Dawn calls Ceres, home."
Dawn is the first spacecraft to explore the orbits of two worlds other than Earth on the same mission. In 2011 it explored the giant asteroid Vesta — the second largest object the asteroid belt — for around a year, before leaving for Ceres.
"We feel exhilarated," said Chris Russell, principal investigator of the Dawn mission at the University of California, Los Angeles (UCLA). "We have much to do over the next year and a half, but we are now on station with ample reserves, and a robust plan to obtain our science objectives."