Comets are seen by reflected sunlight. They may be too small, too distant or a combination of both
Because there aren't always comets!
Comets
The real question is What is ahead of you but you cant see it and the answer is The future.
Comets contain ice.
Yes, but you cant always see them.
TELESCOPE
See related link for a list of periodic and non periodic comets.
when your balls drop
A! i cant see
because they are noarmally near grass
Comets travel in highly elliptical orbits. See link for more.
Yes, because comets are so tiny and dim.