Astrophysics for People in a Hurry (Astrophysics for People in a Hurry Series)

by Neil deGrasse Tyson

As the cosmos continued to expand and cool, growing larger than the size of our solar system, the temperature dropped rapidly below a trillion degrees Kelvin.

Had Earth been much closer to the Sun, the oceans would have evaporated. Had Earth been much farther away, the oceans would have frozen. In either case, life as we know it would not have evolved.

The universe was opaque until 380,000 years after the big bang, so you could not have witnessed matter taking shape even if you’d been sitting front-row center.

Some stars reassemble to form blobs that could be called dwarf galaxies.

Cosmic distances are so vast that the travel time for light to reach us can be millions or even billions of years.