Zenith, the point in the heavens that is directly above the head of the observer. The opposite point, that directly below the observer's feet, is the nadir. Zenith also applies to the highest point a heavenly body appears to reach above the horizon. The sun reaches its zenith at noon.
The man who had some theories about relativity was also an eccentric who gleefully eschewed socks, dodged German military service and spurned social conventions.
Folks in Montana usually expect snow or rain to fall from the sky, not ash. But the 1980 eruption of Mount St. Helens in Washington flung ash across state lines. What is this gritty, gray stuff?