**Analyzing OrbitControls**

I'm currently checking if `OrbitControls` is bundled within `three.min.js`. If not, I'll explore custom implementation or robust alternative camera controls.


**Exploring Custom Controls**

I've confirmed `OrbitControls` isn't core. Developing custom orbit-drag controls seems straightforward and avoids external dependencies. I'm focusing on features: azimuth/altitude rotation via mouse drag, scrolling for zoom, and right-click or shift-drag for panning. This approach should be reliable, even without add-ons.

I am also considering all the features an amazing solar system can include. The Sun could be glowing emissive material, and maybe a point light emanating from it. The Planets would include Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune (and maybe Pluto!). Varied sizes, realistic relative distance/scaling (or stylized for good visuals), varied orbital speeds, tilt, textures/colors (procedurally generated canvas textures or colored materials with bump/specular simulation or nice gradients/rings). Rings will be for Saturn (and maybe Uranus). Moons will be added for Earth (Moon), Jupiter (Io, Europa, Ganymede, Callisto), etc. and last, a Starfield (Particle System)


**Expanding System's Features**

I am now focusing on features that will be critical for user experience and engagement. I'm finalizing orbit lines, UI controls, and an information panel. The UI will have speed controls, info displays, and focus modes. I'm prioritizing intuitive orbit-drag controls: left-drag for orbit, right-drag/shift-drag for pan, and scroll for zoom, with mobile touch controls. Procedural textures, Saturn's ring, and interactive raycasting will be included in the `index.html`.

**Designing the App Structure**

I've decided to start the application's design in `index.html`, utilizing Three.js revision 128. My primary focus is establishing the structural components. I'm thinking of creating a full-screen canvas with an overlay HUD for UI elements like a top bar displaying the title, menus, and perhaps a side panel with more detailed user controls. I also want to separate other UI elements like the bottom and left panels.


**Defining UI Elements**

Now, I'm focusing on defining UI element functionality. The left panel will become the planet directory with quick-select options. I envision a bottom info card displaying detailed planet data when selected. Floating toggles will control orbits, labels, the starfield, and the camera reset. A crosshair will aid in target selection.


**Listing Celestial Bodies**

I'm now cataloging the celestial bodies to include: Mercury through Pluto. For each, I'm noting essential properties: name, radius, distance, speed, color/texture, tilt, moons, and detailed info. I'm considering using procedural canvas textures to uniquely represent each planet. Also, I'm working to create orbit lines, and I'm planning to use `THREE.LineLoop` with `THREE.EllipseCurve`.