Leeds
OUR Sun, like other stars, formed when a cloud of dust and gas began to clump
together in interstellar space. No one quite knows why or how this happened, but
it was the first step in the long and complicated evolution of our rocky planet,
with its iron core and oxygen-rich atmosphere. The first stage was to build a
planet of the right size, using the right materials. But it produced nothing
that we would recognise as “our Earth”. Later, Earth became layered, with a core
rich in iron, a mantle made of silicate minerals and a thin, rigid…
