Instantly, I wished it had occurred to me to have looked up as well as down. I looked up now, and sure enough I spotted the chunk of celestial ice hurtling toward me. It was the size of a bowling ball, and the ice was spiritual in nature, so not only did I have to apply my strength to catch it, I had to focus my soul barrier to prevent it from hurting me even after I broke its momentum. After that, I had to throw it clear of the city.
It took effort, but I wasn't tiring yet. A good thing, because apparently I needed to do it 8 more times. The second comet was twice the size of the first, and the third twice the size of the second. Each comet was bigger than the last, and by the time I'd finished straining to throw the 5th one clear of the city, I was definitely feeling the effects of the exertion.