Diagram of a multilayered hollow (and potentially habitable) Sun. From a victorian 1877 popular science book called half Hours in Air and Sky.

The reason for this belief for the sun at that point seems to stem from the previous observations of Scottish astronomer Alexander Wilson's who focused in recording examining sunspots. Which he was fairly convinced were depressions on the Sun's surface (somewhat accurate and the effect that makes them appear so being known to this day as the Wilson effect), and holes that revealed a non luminous dark surface of "dark globe" underneath a luminous atmosphere. (well, that part a bit less accurate). Further more he was convinced he had observed additional dark shells through them, thus the multi-shell diagram. Although all this might sound a bit silly, in the end one must remember that one is talking about an era before nuclear physics was a thing. The mere fact that the sun was "glowing" was already a mystery with no other scientific explanation other than "Goddidit". So if one miraculous and designed thing exists in the sky, no reason it can't be further designed. And if you think that you have seen a structure clearly intented to insulate the interior from the exterior, then you might as well concluded it is likely so to as to protect someone. Tl;DR: There was a small period in cosmology where astronomy was doing as advanced a thing as figuring out the atmosphere of the gas giants with spectroscopy and yet people still weren't 100% sure the Sun wasn't hollow and inhabited!

And it is worth noting that even so, Ceres accounts for about 39% of the mass of it. If one were to exclude it, then you'd only get an 1102 km diameter object instead. Which drawn together would only look slightly larger than Ceres. (it would be heavier, but volume increases much faster than diameter, so a little bit of diameter nets you a lot more volume)

Keep in mind that despite the mass of the total material in the asteroid belt being so tiny, this is not necesserily the size the original protoplanet (or protoplanets) that may have once broken up to form it had. Since many fragments of it, likely either got ejectected from the solar system, or fallen into/merged with the rest of the existing planets and gas giants. This essentially is what remains of the fragments of it/them, that ended up in a stable enough orbit to be around for us to observe today.

Edmond Halley. Famous and forever immortalized astronomer for accurately mathematically predicting Halley's comet return. Probably a bit less famous and accurate about: His multi-shell hollow earth theory. royalsocietypublishing.org/d…

Back to Halley. He is of cource very much aware of other limitations, such as light. Albait at this point the argument not being anything more beyond "well, there may be other ways to produce light" and essentially later on "well, it would be a waste if the Creator didn't make something so cool".

Yes, that's extremely obviously bird poop/bug smear or similar a far as I am concerned. However I have noticed some interesting comments by people saying "oh yeah, then why does it sometimes move back and forth compared compared to the rest of the hud?" or "oh year, and how come something on top of the lens is in focus"? So here's actually the last mental lego piece of information needed to explain these, which to me as someone who also likes military tech was obvious but realize its probably worth explaining. For starters, check out the cool video attach of some rocket seekers moving. And notice that they move and at the same time, they are inside a plastic "dome". The same thing I can assure you pretty much is going on whatever targetting pod thingy this video is from. In other words, these camera lenses are not bare to the air. They will usually have inbetween another transparant cover, which is there either for aerodynamics, or because, simply put, if you hit a pigeon you'd rather ruin that rather than you expensive sensors/lenses.

A fun case of ancient "Microgravity manufacturing" I stumbled upon. "Shot Towers" were used in the past to manufacture round shot. (which for the longest time was what guns like muskets used). They work like this:

Incidentially a somewhat interesting side fact (in case you had that thought, since I had it as well) is that, no, raindrops dont actually have a "raindrop" shape during flight. Its a myth (possibly due to how they look when they are about to drip from a faucet)