What is 'Antimatter' and Why Is It Surrounding the Earth?

When cosmic rays smash into Earth's atmosphere, which happens all the time, smaller particles are released. Physicists have theorized that some of these smaller particles may be antimatter.* And recent data says they're right.

Why does that matter to you? Because some say such matter could be harnessed for fuel.

The cosmic ray detector PAMELA, which is part of a program carried out by the WIZard collaboration and Russian partners, found a whopping 28 antiprotons during a 850 day period.

Before you jump to conclusions, this number may be more impressive than it sounds. Wired reports:

That might not sound like much, but it’s three times more than would be found from a random sample of the solar wind.

PAMELA, which is an acronym for Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics, was released in 2006 attached to a satellite to seek out such particles. New Scientist explains:

Charged particles called cosmic rays constantly rain in from space, creating a spray of new particles - including antiparticles - when they collide with particles in the atmosphere. Many of these become trapped inside the Van Allen radiation belts, two doughnut-shaped zones around the planet where charged particles spiral around the Earth's magnetic field lines.

Heavier particles take wider paths when they spiral around the planet's magnetic lines, and weaker magnetic field lines also lead to wider spirals. So relatively heavy antiprotons travelling around the weak field lines in the outer radiation belt were expected to take loops so big they would quickly get pulled into the lower atmosphere, where they would annihilate with normal matter. The inner belt was thought to have fields strong enough to trap antiprotons, and indeed that is where they have been found.

The physicists of this discovery stated in the Astrophysical Journal Letters that this is the most abundant source of antiprotons near Earth. New Scientist went on to report future applications for energy produced by the reaction of matter and antimatter, if harnessed, could be used in applications like fuel for ultra-efficient rockets.

*Author's Note: Before delving into the ins and outs of what was discovered and what it means, here's a quick refresher about antimatter and some other concepts related to this discovery. Antimatter is composed of antiparticles, in the same way matter is composed of particles. Antimatter is the equal yet opposite twin of matter. For example, protons have an equal but opposite antiproton; electrons have a positron. CERN's Kid's Corner page explains the concept of antimatter with this visual: picture taking a star-shaped cookie cutter and cutting out the shape in playdough. The star you now hold in your hand is matter, the hole left in the dough is antimatter. At present antiparticles can only exist for a short period of time before they collide with particles and annihilate each other. This annihilation results in high-energy photons. Scientists at CERN in Geneva, Switzerland, experiment with creating and trapping antimatter particles. In November 2010, CERN particle phyicists created and trapped antimatter, but only for a short period of time (170 milliseconds). More recently in May 2011, Wired reported they were able to trap antihelium for just under 17 minutes.