You have a few problems in your code… names, quotes, possible camera placements, lighting issues… First, I would change the names and quotes (not curly). Try this:
const ambientLight = new THREE.AmbientLight(0xffffff, 0.5);
scene.add(ambientLight);
//…
const earth = createCelestialBody(
5,
'https://i.ibb.co/your-earth-texture.jpg',
{ x: -10, y: 0, z: 0 }
);
const mars = createCelestialBody(
3,
'https://i.ibb.co/your-mars-texture.jpg',
{ x: 10, y: 0, z: 0 }
);
//…
window.addEventListener('resize', () => {
renderer.setSize(window.innerWidth, window.innerHeight);
camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();
});