Explanation:
Our universe is filled with galaxies.
Galaxies
-- huge conglomerations of stars,
gas,
dust -- and mysterious
dark matter
are the basic building blocks of the
large-scale universe.
Although distant galaxies move away from each other as the
universe expands, gravity attracts neighboring
galaxies to each other, forming
galaxy groups,
clusters of galaxies,
and even larger expansive filaments.
Some of these structures are visible on one of the most comprehensive maps
of the sky ever made in galaxies: the
APM
galaxy survey map completed in the early 1990s.
Over 2 million galaxies are depicted above in a region 100
degrees across centered toward our
Milky Way Galaxy's south pole.
Bright regions indicate more
galaxies,
while bluer colors denote larger average galaxies.
Dark ellipses have been cut away where
bright local stars
dominate the sky.
Many scientific discoveries resulted from analyses of the map data,
including that the
universe was
surprisingly complex on large scales.
