billions of icy planetesimals are presumed to spin,
trillions of fragments of ices, amonia, and methane
are presumed to mill about
within a light-year in all directions from
the Sun.
Butterfly effect
Small galactic perturbations
send members of the Oort cloud
sailing toward the Sun
except for which
one may claim no water or life
would exist on Earth.
Other examples exist,
although many are fictional.
We people just live our lives.
In addition to predicting the Oort cloud, Jan Oort
discovered the galactic halo, calculated the center of the Milky
Way, and was the first to find evidence for dark matter. Although
Jan Oort predicted the existence of the Oort cloud in 1950, it has
not yet been directly observed. Nevertheless, you should search
the news this fall for Comet ISON, assumed to be a one-time
visitor from the Oort Cloud.
In addition to predicting the Oort cloud, Jan Oort discovered the galactic halo, calculated the center of the Milky Way, and was the first to find evidence for dark matter. Although Jan Oort predicted the existence of the Oort cloud in 1950, it has not yet been directly observed. Nevertheless, you should search the news this fall for Comet ISON, assumed to be a one-time visitor from the Oort Cloud.
See also in The book of science:
Readings on wikipedia:
Other readings: