t: [0.2, 0.5, 0.8, 1],  // blue-green
      u_colorMult:   [0.8, 0.5, 0.2, 1],
    },
    programInfo: programInfo,
    bufferInfo: sphereBufferInfo,
    vertexArray: sphereVAO,
  };

  var moonNode = new Node();
  moonNode.localMatrix = m4.translation(20, 0, 0);  // moon 20 units from the earth
  moonNode.drawInfo = {
    uniforms: {
      u_colorOffset: [0.6, 0.6, 0.6, 1],  // gray
      u_colorMult:   [0.1, 0.1, 0.1, 1],
    },
    programInfo: programInfo,
    bufferInfo: sphereBufferInfo,
    vertexArr