Oort cloud

Q1. What Is Oort Cloud?

The Oort Cloud is a theoretical spherical cloud of predominantly icy planetesimals that is believed to surround the sun at a large distance of up to around 100,000 AU which is approximately 2 light years. This places it in interstellar space, beyond the sun's Heliosphere where it defines the cosmological boundary between the solar system and the region of the sun's gravitational dominance.

The Oort Cloud is through to extend from between 2,000 and 5,000 AU  (0.03 and 0.08 light years) to as far as 50,000 AU (0.79 light years) from the sun, though some estimates place the outer edge as far as 100,000 and 200,000 AU (1.58 and 3.16 light years). The Cloud is thought to be comprised of two regions 1. a spherical outer Oort Cloud of 20,000 – 50,000 AU (0.32 – 0.79 light years), and disc-shaped inner Oort Cloud of 2,000 – 20,000 AU (0.03 – 0.32 light years).

The outer Oort cloud may have trillions of objects larger than 1 km and billions of objects is about 20 kilometers in diameter. Its total mass is not known.