Are We Alone
20 Pages 4930 Words
The prospects of finding life elsewhere in the Solar System
Thirteen thousand years ago, a dazzling meteor flashed into existence in the skies above Antarctica. As it ploughed earthwards, the heat of its fall ripped apart the atoms of the air, leaving behind a brilliant trail that lit up the icy landscape. It would have made a beautiful sight, if anybody had been there to see it. The meteor's surface melted, then vapourised, and as the rocky ball tore towards the ground it slowly shrank. Ordinarily such an object would have been completely destroyed long before making contact with our planet's surface, but this one was not. A small chunk - about two kilograms of it - survived the fall, and lay there, hot and steaming, on the cold Antarctic ice.
Most meteorites that are found on Earth are simply interplanetary debris - small pieces of junk left over from the violent formation of our Solar System, four and half billion years ago. But this particular meteorite was special. It had come from Mars, blasted from its home planet fifteen million years ago by a cosmic impact even more spectacular than the one in which it fell to Earth. This potato-shaped lump of rock, codenamed ALH84001 by the scientists who first discovered it, was a messenger from another world. And buried deep within its baked interior lay what may have been humanity's first tantalising glimpse of an alien lifeform.
Every few years, the red disc of Mars passes particularly close to the Earth, and human observers are afforded an especially good view of the planet that has fascinated mankind since ancient times. This fortunate configuration of the planets is known to astronomers as a "favourable opposition", and one such event occurred in the year 1877. Among the many observers who turned their telescopes towards the Red Planet in that year was the Italian Giovanni Schiaparelli, who was surprised to see a network of dark, greenish lines criss-crossing the planet's rusty ...