Since the 1940s, antimatter comets and meteors have been suggested as one possible explanation for various observed natural phenomena - e.g. 'explosive' meteor strikes, gamma-ray burstsplugin-autotooltip__plain plugin-autotooltip_bigGamma-ray bursts

Gamma-Ray Bursts (GRBs) were first discovered by satellites originally intended to scan for nuclear weapon detonations.They range from bursts of ten milliseconds to several hours, and also have differing energy levels. They are generally unexplained., ball lightningplugin-autotooltip__plain plugin-autotooltip_bigBall Lightning

Ball Lightning refers to luminous, usually spherical, atmospheric objects which vary from a few centimetres to several metres in diameter. They are usually associated with thunderstorms. Anecdotal reports suggest that they can 'pass through' solid objects. etc etc.

If the solar system formed from the collapse of a gaseous, presolar nebula, then any antimatter initially present would have annihilated long before any solid bodies condensed because the annihilation time is much shorter than the collapse time. If substantial amounts (~ ½) of antimatter had been present in the presolar nebula, it is quite likely that nothing would have survived to form the solar system. It should be noted, however, that once formed, condensed bodies of antimatter could survive indefinitely. The "capture" of such antimatter bodies could have led to the presence of antimatter in the solar system.

Source : Annual Review of Astronomy and Astrophysics, Vol. 14:339-372

To date, however, no firm proven evidence of their existence has been found.

Also see :The Antimatter Problemplugin-autotooltip__plain plugin-autotooltip_bigThe Antimatter Problem

According to Big Bang Theory, matter and anti-matter should have been created in equal amounts at the 'beginning' of the Universe. And, in experiments with high-energy particle accelerators, that is exactly what happens. Baryons (i.e. 'heavy' particles such as neutrons, protons, and their constituent quarks) and their anti-particle equivalents (anti-baryons) are created in equal numbers.