- In astronomy, the term "disk" may be applied to a flattened, circular region of gas, dust, and/or stars. It may refer
to material surrounding a newly-formed star, material accreting onto
a black hole or neutron star, or the large region of a spiral galaxy
containing the spiral arms.
- A disk is also the apparent circular shape of the Sun, a planet, or the Moon when
seen in the sky or through a telescope.