O is for Oort Cloud

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I thought I'd continue the theme we began with the J is for Jupiter and K is for Kuiper Belt posts.

The Oort Cloud is an immense spherical cloud surrounding the planetary system and extending approximately 1 to 3 light years (depending on who you listen to), about 30 trillion kilometers from the Sun. This vast distance is considered the edge of the Sun's orb of physical, gravitational, or dynamical influence.

Within the cloud, comets are typically tens of millions of kilometers apart. They are...