Animate[
def=Rectangle[{-20,-12},{0,30}];
chi=Rectangle[{-20,-50},{x+1000,-8}];
sora=Rectangle[{-40,-40},{x+1000,y+1000}];
kumo={
Disk[{75,200},20],Disk[{100,200},20],Disk[{125,200},20],
Disk[{275,200},20],Disk[{300,200},20],Disk[{325,200},20],
Disk[{475,200},20],Disk[{500,200},20],Disk[{525,200},20],
Disk[{675,200},20],Disk[{700,200},20],Disk[{725,200},20],
Disk[{875,200},20],Disk[{900,200},20],Disk[{925,200},20]
};
yami=Rectangle[{-40,300},{x+1000,3000}];
UFO={{Gray,Disk[{x,550},20]},
{Black,Rectangle[{x-25,520},{x+25,550}]},
{Yellow,{Disk[{x-15,550},8],Disk[{x,550},8],Disk[{x+15,550},8]}}
};
yama={
Disk[{150,-12},{30,40}],
Disk[{400,-12},{30,40}],
Disk[{650,-12},{30,40}],
Disk[{900,-12},{30,40}],
};
moon={Yellow,Disk[{500,700},100]};
en={Disk[{x,y+6},c],
Rectangle[{x-0.1,y+6},{x+0.1,y+3-c}]};
car=Rectangle[{x-3.5,y+1-c},{x+3.5,y+4.5-c}];
taiya={Disk[{x-2,y+1-c},1],
Disk[{x+2,y+1-c},1]
};
x=a*t-12;
y1=30+500+(-0.01+d)*(t-t0)*(t-t0);
t0=(12+c/2)/a;
t1=(1/(-3.` (a^2)+(a^2) c))0.5` (-72.` a+21.` a c+a (c^2)-34.64101615137754` (Sqrt[126.` (a^4)-39.` (a^4) c-1.` (a^4) (c^2)]));
y=30+c;
If[x≥c/2,y=30+c+(-0.01+d)*(t-t0)*(t-t0)];If[y≤-12,{y=-12+c,x=a*t1-12}];
If[y≥550,y=550-c];
d=c/300;

Graphics[{{LightBlue,sora},{Black,yami},moon,{White,kumo},{Green,yama},{Orange,en},{Red,car},{Gray,taiya},UFO,{Brown,def},{Blue,chi}},PlotRange->{{-18,x+y/2+40},{-20,y+x/3.1+40}}],{{t,0},0,1200},{{c,1,"フウセン"},1,5},{{a,0.1,"初速度"},0.1,1.0},AnimationRunning->False]