The Earth is surrounded by a belt of antimatter - and it could perhaps be used to power future spacecraft, a team of scientists has suggested.
The band of antiprotons was detected by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (Pamela) satellite, launched in 2006 to study cosmic rays.
It's found that as cosmic rays slam into the Earth's atmosphere, particles are produced that include the elusive antiprotons. They lie several hundred kilometers up in the Earth's inner Van Allen belt, trapped by our magnetic field.
Most are annihilated through collisions with normal matter, but a high concentration was found in an area known as the South Atlantic Anomaly. They represent 'the most abundant source of antiprotons near the Earth,' says the team.
And study author Alessandro Bruno of the University of Bari has even suggested to the BBC that the antimatter could even one day be used to power spacecraft.
Antimatter particles release an enormous amount of energy when they come into contact with normal matter - energy density os to or three times higher than nuclear reactions and ten times more than the best chemical propellants used in current spacecraft.
This development could be rather a long way off, however - so far, the record for reliably containing antimatter lies at just sixteen and a half minutes.