y = Math.sin(time) * 0.1;
                this.mesh.rotation.y += 0.01;

                // Update glow mesh
                this.mesh.matrix.decompose(this.glowMesh.position, this.glowMesh.quaternion, this.glowMesh.scale);
            };

            ready = () => this.initMesh();
        }

        class DarkPlanet extends Group {
            constructor() {
                super();

                this.position.x = -2.5;

                // 25 degree tilt like Mars
                this.rotation.z = Math