The Universe

space · cosmos · everything · time

The Big Bang. The universe started about 13.8 billion years ago from an incredibly hot, dense point and has been expanding outward ever since, like an enormous balloon getting bigger and bigger.

Galaxies everywhere. The universe is so huge that we can see about 93 billion light-years across it, and it contains billions of galaxies, each with billions of stars.

Still growing. Every second, space itself is stretching and expanding, pushing galaxies farther apart from each other in all directions.

Made of everything. The universe contains all forms of matter (like atoms and planets) and energy (like light and heat), arranged from the tiniest particles to the largest structures.

Size unknown. Scientists can only see part of the universe called the observable universe, but they don't know how big the total universe really is or if it even has an end.