We really don't know the full answer to that. We can only answer that we know that within their funerary religion the sky plays a major role where events will take place for eternity. I think the one thing anyone learns studying ancient Egypt is that they had a notion of the cosmos as a cycle. Everything continues and the mummification process is part of that. Death is not the end.
Death is a transition.
The same is true in watching the sky. The Egyptians were well aware that throughout the year, the stars that were visible in the heavens were not in the same exact place from day to day. And yet, they also knew that the same sets of stars were going to reappear next year at the same time. And very early on, they developed very intricate sky maps that would indicate which groups of stars were visible in Egypt at different times of the year and they used them to make their calendar with. I mean time in a true sense, but also a really eternal sense that the Egyptians were taken with.