Colin Humphreys and W. G. Waddington of Oxford University considered the possibility that a lunar, rather than solar, eclipse might have taken place. They concluded that such an eclipse would have been visible, for thirty minutes, from Jerusalem and suggested the gospel reference to a solar eclipse was the result of a scribe wrongly amending a text. Historian David Henige dismisses this explanation as 'indefensible' and astronomer Bradley Schaefer points out that the lunar eclipse would not have been visible during daylight hours.