Why are the 7 MCU Celestials so Different in Size and design, I mean look at the ones seen in the movies. They are cosmic beings of immense power and capabilities but as a race of creatures, they look so different from one another and at the same time their sizes differ not just in slight manner but in magnitudes.
The first celestial seen was Knowhere, seen in Guardians of the galaxy vol. 1 it was a severed head of a celestial. The Tivian group set up mining operations inside of it to collect valuable brain & spinal tissue of the dead god. As we can see, the mining colony was huge as it encompasses the entire inside of the skull. This also shows the celestial was of organic origin. The Size of knowhere would have been 1-2km from neck to the top of the head. And this was just a fraction of the body size. This would have put the entire being at around 5-10 km tall or 3-6 miles in height.
Now lets see the second celestial that was shown in the MCU, and it was in the same movie when the guardians met up with taneleer tivan or otherwise known as the collector and he showed them the power stone and its previous owner, a celestial known as Eson the searcher. This being was gigantic in size but nowhere as big as even Knowhere, he would have been at least 2000 ft tall. This conflicts with the concept art of the celestials as was seen from last year, the one where Arishem, Nezzar, Jemiah and Hargen were seen walking towering above the clouds standing at maybe 6km tall or 3.7mi.
Now that’s that, we can clearly say that maybe Knowhere and the others in the concept design were of comparable size except for eson the searcher who was like a mouse as compared to the others. So here we get really freaky in both design and size difference, here we come to Ego the living Planet. This guy right here is of a different stock, he has a human extension of himself, a normal size human but the true form was that of a dwarf planet around 3000km or 1850 miles in diameter, around the size of Earth’s moon. Totally different from the other robotic looking humanoid celestials. So whats the deal right? Why are Celestials so different from each other in the MCU.
Lastly now we see two others in the trailer of MCU’s latest movie, the eternals. Arishem the Judge was first seen as a humanoid robotic being in the center of a meeting between the eternals. Even though he was just a holographic projection, he was tall and lean. Then the second time we see him, he was in space and what seems to be space debris or meteors orbiting around him. This would have put him easily in the hundreds of kilometers or miles in height. Then finally we see another celestial known as Jemiah the analyser and he was the biggest yet, analyzing the birth of a planet or a star between his hands. This is cosmic scale to say the least.
So, What the hell is with these difference in scales? From a 2000 foot eson to a planet sized Ego to a cosmic being the size of stars. Well, the answer might be in the movie and since its not out yet, we can only speculate. I would say that these celestials can alter their size over the years with their age and understanding of cosmic powers, they can alter themselves to interact with normal sized people as in the case of Ego and at the same time having a true self that is thousands of miles in size. In the case of the others which are considerably older than the living planet, they can consciously be as big as stars or titans walking on a planet, depending on the need and the circumstances.