... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. February 7, 1998 . COBE Hotspots: The Oldest Structures Known . ... After computer processing to remove contributions from nearby objects and the effects of the earth's motion , the map shows temperature variations in the early Universe as red "spots". These spots are the oldest, most distant structures known. ... About APOD > . ...