Original: Friday , April 13 -- The asteroid 99942 Apophis ( previously better known by its provisional designation 2004 MN4 ) will pass within 30,000 km ( 18,600 mi ) of the Earth , very briefly appearing as bright as 3rd magnitude .
Simplified: Friday , April 13 -- The asteroid 99942 Apophis ( previously better known by its provisional designation 2004 MN4 ) will pass within 30,000 km ( 18,600 mi ) of the Earth .