The human mind may find it difficult to conceptualize a cosmic cloud so colossal it surrounds the Sun and eight planets as it extends trillions of miles into deep space.
The spherical shell known as the Oort Cloud is, for all practical purposes, invisible. Its constituent particles are spread so thinly and so far from the light of any star, including the Sun, that astronomers simply cannot see the cloud, even though it envelops us like a blanket.
It is also theoretical. Astronomers infer the Oort Cloud is there because it’s the only logical explanation for the arrival of a certain class of comets that sporadically visit our solar system. The cloud, it turns out, is basically a gigantic reservoir that may hold billions of icy celestial bodies.
Two of those bodies will pass by Earth in the days leading up to Halloween. Tsuchinshan-ATLAS, also known as Comet C/2023 A3, will be at its brightest and likely visible to the naked eye for a week or two after Oct. 12, the day it’s closest to Earth – just look to the western sky shortly after sunset. As the days pass, the comet will get fainter and move to a higher part of the sky.
