The sun is a medium-sized star located near the edge of a disk- shaped
galaxy of stars, part of which can be seen as a glowing band of light that
spans the sky on a very clear night. The universe contains many billions
of galaxies, and each galaxy contains many billions of stars. To the naked
eye, even the closest of these galaxies is no more than a dim, fuzzy spot.
NSES Content Standard D
Earth and Space Science: Origin and evolution of the universe Grades 9-12, page 190 Early in the history of the universe, matter, primarily the light atoms hydrogen and helium, clumped together by gravitational attraction to form countless trillions of stars. Billions of galaxies, each of which is a gravitationally bound cluster of billions of stars, now form most of the visible mass in the universe. |