Three years ago Cemex would tell customers it would try to make deliveries of ready-mix concrete (the kind that comes in the trucks with rotating barrels) within three hours of agreed delivery times.
Matija Cuk, from the Seti Institute, and colleagues ran new simulations in which the early Earth was rotating on its axis in just a few hours prior to the impact - compared to the present 24 hours.
Egyptian officials have been keen to note that Mr Morsi would stay only for the few hours needed formally to pass the rotating chairmanship of the Non-Aligned Movement on from Egypt to Iran: a summit meeting, held every three years, was declared open on August 30th.
Consumers and businesses are asked to reduce their electricity use during peak electricity hours from 3 to 7 p.m. today to avert the need for rotating outages.