Philae wake-up

Astronomers proposed a novel explanation Monday for the strange appearance of the comet carrying Europe's robot probe Philae through outer space: alien microscopic life. Philae woke up in June after nearly seven months in hibernation as it hurtled towards the Sun on the back of a comet. The mission seeks to unlock the long-held secrets of comets -- primordial clusters of ice and dust that scientists believe may reveal how the Solar System was formed.VIDEOGRAPHIC