The "Vomit Comet" refers to a NASA program that introduces astronauts to the feeling of zero-gravity spaceflight.
Recruits climb aboard a specially fitted aircraft that dips and climbs through the air to simulate the feeling of weightlessness in 20- to 25-second intervals.
A class can be declared with modifier public.when the class is visible to all classes everywhere and there is no modifier,it can be visible at its own package.