Big bang theory

The big bang is how
astronomers explain the way
the universe began. It is the
idea that the universe began
as just a single point, then
expanded and stretched to
grow as large as it is right
now (and it could still be
stretching).

In 1927, an astronomer named Georges
Lemaître had a big idea. He said that a
very long time ago, the universe started
as just a single point . He said the
universe stretched and expanded to get
as big as it is now, and that it could
keep on stretching.