Solar Partial Eclipse

Just testing :)

HTML

<div id="sky">
  <div id="sun"></div>
  <div id="moon"><b/></div>
</div>

CSS

html,
body,
#world {
  width: 100%;
  height: 100%;
  overflow: hidden;
  margin: 0;
  padding: 0;
}

#sky {
  width: 100%;
  height: 100%;
  background: #87ceeb;
}

#sun {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 150px;
  height: 150px;
  border-radius: 75px;
  background: yellow;
}

#moon {
  position: absolute;
  width: 150px;
  height: 150px;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -45%);
}

#moon b {
  display: block;
  position: relative;
  transform: rotate(25deg);
  width: 150px;
  height: 150px;
  border-radius: 75px;
  background-color: rgb(135, 206, 235);
  transform-origin: 50% 300%;
}

#sky:hover b  {
  animation: transit 5s linear infinite,
             darknes 5s linear infinite;
}
#sky:before {
    background-image: radial-gradient(circle farthest-corner, black, #87ceeb 400px);
    content: '';
    display: block;
    height: 100%;
    width: 100%;
    position: absolute;
    opacity: 0;
}
#sky:hover:before {
  animation: eclipse 5s linear infinite;
}

@keyframes eclipse {
  0%   { opacity: 0; }
  5%  { opacity: 0; }
  40%  { opacity: 0.99; }
  50%  { opacity: 1; }
  60%  { opacity: 0.99; }
  95%  { opacity: 0; }
  100% { opacity: 0; }
}

@keyframes transit {
  0%   { transform: rotate(25deg); }
  40%  { transform: rotate(1deg); }
  50%  { transform: rotate(0deg); }
  60%  { transform: rotate(-1deg); }
  100% { transform: rotate(-25deg); }
}

@keyframes darknes {
  0%   { background-color: rgb(135, 206, 235); }
  5%   { background-color: rgb(135, 206, 235); }
  40%  { background-color: rgb(13, 20, 23); }
  50%  { background-color: rgb(0, 0, 0); }
  60%  { background-color: rgb(13, 20, 23); }
  95%  { background-color: rgb(135, 206, 235); }
  100% { background-color: rgb(135, 206, 235); }
}