Complex sentence: The primary scientific arguments against ETH were summarized by astronomer and UFO researcher J. Allen Hynek during a presentation at the 1983 MUFON Symposium, where he outlined seven key reasons why he could not accept the ETH.
Split into simpler sentences: The primary scientific arguments against ETH were summarized by astronomer and UFO researcher J. Allen Hynek during a presentation at the 1983 MUFON Symposium. During which time he outlined seven key reasons why he could not accept the ETH.