The Guardian reports: Nearly half of the atoms that make up our bodies may have formed beyond the Milky Way and travelled to the solar system on intergalactic winds driven by giant exploding stars, astronomers claim.

The dramatic conclusion emerges from computer simulations that reveal how galaxies grow over aeons by absorbing huge amounts of material that is blasted out of neighbouring galaxies when stars explode at the end of their lives.

Powerful supernova explosions can fling trillions of tonnes of atoms into space with such ferocity that they escape their home galaxy’s gravitational pull and fall towards larger neighbours in enormous clouds that travel at hundreds of kilometres per second.

Astronomers have long known that elements forged in stars can travel from one galaxy to another, but the latest research is the first to reveal that up to half of the material in the Milky Way and similar-sized galaxies can arrive from smaller galactic neighbours.

Much of the hydrogen and helium that falls into galaxies forms new stars, while heavier elements, themselves created in stars and dispersed in the violent detonations, become the raw material for building comets and asteroids, planets and life. [Continue reading…]