hi i need help with this script idk how to trigger it when the meteors hit land how do i do it?

howhi = 100 
howfst = 4
while true do
	local nmbr = 0
	while nmbr < howhi do
		script.Parent.CFrame=CFrame.new(script.Parent.Position + Vector3.new(0, howfst/4 , 0)) * CFrame.fromAxisAngle(Vector3.new(0,1,0), 0)
		wait(0.25)
		nmbr = nmbr + (howfst/4)
	end
	script.Parent.CFrame=CFrame.new(script.Parent.Position + Vector3.new(0, -(howhi), 0)) * CFrame.fromAxisAngle(Vector3.new(0,1,0), 0)
	wait(0.25)
	nmbr = 0
end