Every day, Earth is bombarded by materials from outer space. Most of them are small fragments - cosmic dust and particles as small as a grain of sand - which burn up completely when entering the atmosphere, producing streaks of light that we recognize as shooting stars or meteors. However, occasionally, larger fragments manage to survive the dangerous journey through the atmosphere and reach the Earth's surface as meteorites.
Meteorites are hard objects from outer space that manage to survive the crossing of the atmosphere and reach the Earth's surface without being completely destroyed. Their journey is dramatic - when entering the atmosphere at speeds between 11 to 72 kilometers per second, friction with the air heats their surface to thousands of degrees Celsius, melting and vaporizing their outer layer. However, their inner part may remain cool - meteorites that fall are often cool to the touch even though their surface has just burned.
Most meteorites come from three main sources. First, from asteroids - rocky bodies located in the Asteroid Belt between Mars and Jupiter's orbits. When asteroids collide with each other or are disturbed by Jupiter's gravitational pull, their fragments can be sent towards Earth. Second, there are meteorites from the Moon - fragments separated from the Moon's surface due to asteroid impacts and eventually falling to Earth. Third, and most interesting, are meteorites from Mars - rocks thrown into space by large asteroid impacts on Mars and finally ending up on Earth after millions of years traveling through outer space.
There are three main types of meteorites based on their composition. Stony meteorites are the most common, consisting of silicate minerals similar to Earth rocks. Within this category, there is a subgroup called chondrites - meteorites containing small round particles called chondrules, considered among the oldest materials in the solar system formed about 4.6 billion years ago. Iron meteorites mainly consist of iron and nickel, and are believed to originate from the differentiated planetary cores of asteroids - a process where heavier materials like iron sank to the center of the asteroid. Stony-iron meteorites are the rarest, combining a mixture of rock and metal.
The discovery of meteorites is a rare but significant event. So far, more than 65,000 meteorites have been found and cataloged worldwide. Antarctica is the best location for meteorite discoveries in the world - thick blue ice layers and strong winds cause meteorites to accumulate in certain areas and remain preserved for thousands of years. More than 45,000 meteorites have been found in Antarctica alone.
Scientifically, meteorites are an invaluable treasure. They allow scientists to study the chemical composition and mineralogy of celestial bodies that humans cannot visit. Studies of meteorites have revealed information about the formation of the solar system, the processes that occurred in our progenitor star before the birth of the Sun, and even evidence of the presence of water and complex organic materials in outer space - opening possibilities about the origins of life on Earth and elsewhere.