NASA image

nebulae are interstellar clouds

they are composed of dust, hydrogen gas and
ionized gases referred to as plasma

in time, these materials will coalesce due to the
combined influences of gravity and magnetic fields;

they will coalesce to form stars

these stars will burn their constituent materials
through nuclear fusion; creating new and progres-
sively heavier elements

they will eventually end their life cycles in a colossal
explosions known as supernovae

these explosions will spew out dust, hydrogen gas,
ionized gases and traces of the heavier elements

over time, the cycle will repeat itself; and another
generation of stars will form

all this can be seen as a kind of recycling process -
but one done on a cosmic scale - involving unimagin-
able energy, mass, distances and time

and nebulae can be seen as cosmic recycling centers
where the jettisoned material of old stars is recom-
bined to produce new stars

and these new stars, given elements such as carbon
and iron, in sufficient quantity and proper proportion,
may produce something else -

rocky planets like ours and beings like us





the above is an excerpt from the History Channel's
Universe series