Phil Plait is an astronomer, author, and science advocate. His blog, Bad Astronomy, is hosted by Discover Magazine, and he writes about news and current issues facing science. A common topic is astronomical doomsday: ways mythical and real the world can end. He’s fascinated by asteroid and comet impacts, and is a big supporter of finding, tracking, and ultimately deflecting any dangerous rocks heading our way. He spoke on this topic in Boulder on 11 October 2011.
Apophis is of concern, and the inimitable astrophycist Neil deGrasse Tyson has already spoken about this celestial body with great verve, conviction, and humour. On 19 February 2008, he expounded on Apophis, while visiting California.
NASA’s Near Earth Object Program optimistically proclaims that the ‘future for Apophis on Friday, April 13 of 2029 includes an approach to Earth no closer than 29,470 km (18,300 miles, or 5.6 Earth radii from the center, or 4.6 Earth-radii from the surface) over the mid-Atlantic, appearing to the naked eye as a moderately bright point of light moving rapidly across the sky. Depending on its mechanical nature, it could experience shape or spin-state alteration due to tidal forces caused by Earth’s gravity field. This is within the distance of Earth’s geosynchronous satellites. However, because Apophis will pass interior to the positions of these satellites at closest approach, in a plane inclined at 40 degrees to the Earth’s equator and passing outside the equatorial geosynchronous zone when crossing the equatorial plane, it does not threaten the satellites in that heavily populated region. Using criteria developed in this research, new measurements possible in 2013 (if not 2011) will likely confirm that in 2036 Apophis will quietly pass more than 49 million km (30.5 million miles; 0.32 AU) from Earth on Easter Sunday of that year (April 13)’.