Tuesday Astronomy class

The midterm I expected to write this morning has been delayed until Thursday, and my relief is enormous.

The Sun is 8000 parsecs from the center of the Milky Way. There are layers of vast empty space from the area circled by the quarks of an atom's nucleus to the area circled by the atoms's electrons, to the area circled by the Moon around the Earth, the Earth around the Sun, the Sun around the black hole at the center of our galaxy, the billions of galaxies so distant the light from the farthest is 25 billion light years away, with only a few particles floating in the vacuum between them. The universe is the thinnest pattern of forces and specks.