CSS Animation: A circle with smaller circles orbiting it.

#gratitude

Here is what we will be making

Starting with the HTML

We create a container .container which centers all other content
Another container .hero-circle that contains the content
Add img inside .hero-circle
Created another container .hero-rotate inside .hero-circle
Lastly we add 4 divs .planet inside .hero-rotate each container an img

HTML

<div class="container">
  <div class="hero-circle">
    <img class="inner-img"
      src="https://images.unsplash.com/photo-1465414829459-d228b58caf6e?ixlib=rb-0.3.5&q=80&auto=format&crop=entropy&cs=tinysrgb&w=600&h=338&fit=crop&s=7ab1744fe016fb39feb2972244246359"
      alt="" />
    <div class="hero-rotate" id="circle">
      <div class="planet">
        <img
          src="https://images.unsplash.com/photo-1465414829459-d228b58caf6e?ixlib=rb-0.3.5&q=80&auto=format&crop=entropy&cs=tinysrgb&w=600&h=338&fit=crop&s=7ab1744fe016fb39feb2972244246359"
          alt="" />
      </div>
      <div class="planet">
        <img
          src="https://images.unsplash.com/uploads/1413142095961484763cf/d141726c?ixlib=rb-0.3.5&q=80&auto=format&crop=entropy&cs=tinysrgb&w=600&h=338&fit=crop&s=86dc2dcb74588b338dfbb15d959c5037"
          } alt="" />
      </div>
      <div class="planet">
        <img
          src="https://images.unsplash.com/photo-1484402628941-0bb40fc029e7?ixlib=rb-0.3.5&q=80&auto=format&crop=entropy&cs=tinysrgb&w=600&h=338&fit=crop&s=6237e62a10fa079d99b088b0db0144ac"
          alt="" />
      </div>
      <div class="planet">
        <img
          src="https://images.unsplash.com/uploads/141310026617203b5980d/c86b8baa?ixlib=rb-0.3.5&q=80&auto=format&crop=entropy&cs=tinysrgb&w=600&h=338&fit=crop&s=882e851a008e83b7a80d05bdc96aa817"
          alt="" />
      </div>
    </div>
  </div>
</div>

Now The CSS

Our outermost div (.container) is covers the entire screen and centers .hero-circle. We'll also add custom properties for the diameter(width and height) of the .hero-circle and the diameter of .planet. This way all we need to do is change the value of those custom properties to make it responsive on small screens

.container {
    display: grid;
    width
    height:100vh;
    place-items: center;
    overflow: hidden;
    background-color: black;
    --circleDiameter: 300px;
    --planets: calc(var(--circleDiameter) / 5)
}

Now we set the width and height of our content container .hero-circle to the --circleDiameter custom property

.hero-circle {
    position:relative;
    width: var(--circleDiameter);
    height: var(--circleDiameter)
}

What's next is to place the center image at the center of .hero-circle

.inner-img {
  position:absolute;
  top:50%;
  left:50%;
  transform: translate(-50%,-50%);
  border-radius:10px;
  width:90px;
  height:90px;
}

that's one way to center a div 😉

We then create the big circle .hero-rotate

.hero-rotate {
    position: relative;
    top: -7px;
    left:-7px;
    width: 100%;
    height: 100%;
    border: 7px solid white;
    border-radius: 100%;
    animation: rotate 30s linear infinite;
}

We'll add the animation later

Add styles to .planets and the image inside each planet

.planet {
    position: absolute;
    width: var(--planets);
    height: var(--planets);
    border-radius: 100%;
    animation: maintain 30s linear infinite;
}

.planet>img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border: 5px solid white;
    box-shadow: 0 0 5px 0 rgba(0, 0, 0, 0.3);
    border-radius: 50%;
    animation: scale 1s linear infinite alternate; 
}

At this point we haven't added the animations yet and we should have something like this.

You only see one image on the circle because they are stacked on each other.

To place the .planets evenly around the bigger circle .hero-rotate, we'll be using the --planets custom property to calculate where to place each circle for responsiveness.
Since there are four .planets we would place them top-center, left-center, bottom-center and right-center

place .planets

.planet:nth-child(1) {
    top: calc(-1 * var(--planets) / 2);
    left: calc(var(--circleDiameter)/ 2 - var(--planets) / 2)
}

.planet:nth-child(2) {
    top: calc(var(--circleDiameter)/ 2 - var(--planets) / 2);
    right: calc(-1 * var(--planets) / 2);
}

.planet:nth-child(3) {
    top: calc(var(--circleDiameter)/ 2 - var(--planets) / 2);
    left: calc(-1 * var(--planets) / 2);
}

.planet:nth-child(4) {
    left: calc(var(--circleDiameter)/ 2 - var(--planets) / 2 );
    bottom: calc(-1 * var(--planets) / 2);
}

You can adjust the position as you like

Animations

Animations are simple.
First we rotate the outer circle .hero-rotate which will make it seem like it's the .planets that are moving
the rotate animation

@keyframes rotate {
    0% {
        transform: rotate(0)
    }
    100% {
        transform: rotate(360deg);
    }
}

From the above preview we could see that the images are turning over because of the rotatoin and we don't that.
To solve that we simply make .planet rotate in the opposite direction and also add scale animation to the images

@keyframes maintain {
    0% {
        transform: rotate(0);
    }

    100% {
        transform: rotate(-360deg);
    }
}

@keyframes scale {
    0% {
        transform: scale(1.2);
    }

    100% {
        transform: scale(1);
    }
}