How is this possible?  The simple answer is "science".  Both our Moon and planet Mars have only an extremely tenuous exosphere and lack the substantial atmospheric protection that shields our planet from most incoming meteoroids. As a result, asteroid impacts occur frequently on their surfaces. These powerful collisions can eject material into space, and on rare occasions, some of these fragments are propelled into Earth-crossing orbits. If a fragment survives its fiery passage through Earth's atmosphere and reaches the ground, it becomes known as a meteorite.

When a suspected lunar meteorite is recovered—often by experienced meteorite hunters—a sample is submitted for scientific analysis. Using petrographic thin sections, chemical testing, and isotopic studies, Meteoriticists compare the specimen's composition to known lunar materials. Its lunar origin is then confirmed through a combination of mineralogical, chemical, and isotopic signatures that match lunar samples returned to Earth by NASA's Apollo missions. 

The same goes for Martian meteorites.  The most definitive evidence of Mars comes from atmospheric gas trapped inside the rock!  Martian meteorites contain tiny bubbles of gas sealed within glassy inclusions. When analyzed using mass spectrometry, the gas composition matches the Martian atmosphere exactly as measured directly by NASA’s Viking landers in the 1970s and confirmed by later missions like Curiosity. The match is so specific that there's no other natural source on Earth (or elsewhere) with the same gas profile.

Once the meteorites are studied and classified, these rare extraterrestrial specimens find their way into museums, universities, research collections, and private collections around the world.

Curious what it might be like to live on Planet Mars?  Click here to read a glimpse!