Judgment Day - Apophis the Destroyer
Keith Hazelton
April 12, 2007
As if we didn't have anything else to worry about, here comes some dandy news from outer space. Asteroid 99942 Apophis, a thousand-foot diameter chunk of rock discovered in 2004, will rendezvous with Earth again on April 13, 2029 (a Friday, of course), hopefully slipping by us at a near-miss distance of about 18,000 miles.
That's closer than many satellites and well-within the Moon's orbit, and Apophis, the Greek name for an Egyptian god of darkness and chaos – naturally – will be visible to the naked eye in parts of Europe North Africa and western Asia as it whizzes by. Talk about close encounters of the worst kind, but wait, it gets better.
In 2004, when discovered, Apophis and Earth came within cosmic waving distance at 9 million miles. In 2029, it will sweep above us by less than 20,000 miles, close enough to our planet for its gravity to possibly alter Apophis's trajectory for a really close encounter a few years later.
Early on scientists estimated a 1-in-10,000 chance Apophis could hit Earth on Sunday, April 13, 2036. And you thought we only had to worry about global warming, overpopulation, peak oil, nuclear war, religious intolerance, AIDS, terrorist attacks, avian flu, earthquakes, tsunamis, supervolcanoes, rising sea levels, death and taxes.
David Morrison, a space scientist and asteroid specialist at NASA’s Ames Research Center, situated in Silicon Valley, California, says the possibility of Apophis hitting Earth on April 13, 2036 is real, even if the once-slight probability now seems to be even smaller (a 1-in-45,000 chance as of the most recent calculation in October 2006).
These probabilities represent uncertainties in our knowledge of the orbit, not a failure of the science,” Morrison said. But whether the asteroid will strike Earth or not, Morrison concluded, the challenge is to resolve which case is correct. “With more observations over a longer time span, we will be able to tie this down.”
The last major near-Earth-object (NEO) to strike the planet was near the Tunguska region of Siberia in 1908, an estimated 200-foot-diameter object which likely exploded above ground, producing a shock wave that rearranged more than 800 square miles of remote landscape and kicking up dust that altered evening sunsets for several days.
The Tunguska blast event corresponded to an estimated at 10-20 megatons of TNT, equivalent to the most powerful nuclear bomb detonated by the United States. By comparison, the atomic bomb detonated over Hiroshima on August 6, 1945 produced an explosion of roughly 13 kilotons of TNT, at least a thousand times less destructive than Tunguska.
Apophis, however, could generate 1,000 – 1,200 megatons of destructive energy, five or six times that of the volcanic eruption of Krakatoa in 1883.
That explosive eruption ejected into the atmosphere more than 25 cubic kilometers of rock, dust and ash and its sound was heard more than 3,000 miles away. As ash and dust circumnavigated the globe, average temperatures declined in many areas for several years and it created optical atmospheric effects such as spectacular, deeply colorful sunsets and “blue” moons.
(Some suggest the blood-red sky shown in Edvard Munch's famous 1893 painting “The Scream” is an accurate depiction of the sky over Norway after the eruption. Munch said: "suddenly the sky turned blood red ... I stood there shaking with fear and felt an endless scream passing through nature.")
An Apophis-sized asteroid impact would be exponentially more devastating than Krakatoa, not only because of the possibility of a dry-land impact in a populated area, but more so due to the massive quantities of dust and dirt which would be lifted into the atmosphere and the resultant “nuclear winter” as the clouds blocked sunlight for months. An ocean impact would create massive tsunamis with destructive forces unlike anything mankind can imagine.
(To more fully imagine the consequences of nuclear winter, read Cormac McCarthy's 2006 novel The Road, which offers a chilling glimpse of post-apocalyptic life on Earth for the survivors of an undefined catastrophe.)
We'll get a couple more shots at refining our calculations. Apophis and Earth get together again observationally in 2013 and 2021, which scientists hope will give them enough data to conclude with even more accuracy than the current 99.9978 percent likelihood a 2036 impact scenario can be ruled out. That 0.0022 percent chance – one in 45,000 – of collision cannot be eliminated until after the gravitational effects of the 2029 close encounter are more reliably defined.
Perhaps more fittingly than can be comprehended by human minds, April 13, 2036 will be Easter Sunday, the day hundreds of millions of Christians celebrate the believed resurrection of Jesus of Nazareth that is the basis of their faith.
Christians expectantly have been waiting through the ages for Jesus to return, the “second coming” prophesied to usher in a thousand-year kingdom of God on Earth. If Jesus arrives with Apophis in fewer than 30 years, he may find little left over which to reign.
That's closer than many satellites and well-within the Moon's orbit, and Apophis, the Greek name for an Egyptian god of darkness and chaos – naturally – will be visible to the naked eye in parts of Europe North Africa and western Asia as it whizzes by. Talk about close encounters of the worst kind, but wait, it gets better.
In 2004, when discovered, Apophis and Earth came within cosmic waving distance at 9 million miles. In 2029, it will sweep above us by less than 20,000 miles, close enough to our planet for its gravity to possibly alter Apophis's trajectory for a really close encounter a few years later.
Early on scientists estimated a 1-in-10,000 chance Apophis could hit Earth on Sunday, April 13, 2036. And you thought we only had to worry about global warming, overpopulation, peak oil, nuclear war, religious intolerance, AIDS, terrorist attacks, avian flu, earthquakes, tsunamis, supervolcanoes, rising sea levels, death and taxes.
David Morrison, a space scientist and asteroid specialist at NASA’s Ames Research Center, situated in Silicon Valley, California, says the possibility of Apophis hitting Earth on April 13, 2036 is real, even if the once-slight probability now seems to be even smaller (a 1-in-45,000 chance as of the most recent calculation in October 2006).
These probabilities represent uncertainties in our knowledge of the orbit, not a failure of the science,” Morrison said. But whether the asteroid will strike Earth or not, Morrison concluded, the challenge is to resolve which case is correct. “With more observations over a longer time span, we will be able to tie this down.”
The last major near-Earth-object (NEO) to strike the planet was near the Tunguska region of Siberia in 1908, an estimated 200-foot-diameter object which likely exploded above ground, producing a shock wave that rearranged more than 800 square miles of remote landscape and kicking up dust that altered evening sunsets for several days.
The Tunguska blast event corresponded to an estimated at 10-20 megatons of TNT, equivalent to the most powerful nuclear bomb detonated by the United States. By comparison, the atomic bomb detonated over Hiroshima on August 6, 1945 produced an explosion of roughly 13 kilotons of TNT, at least a thousand times less destructive than Tunguska.
Apophis, however, could generate 1,000 – 1,200 megatons of destructive energy, five or six times that of the volcanic eruption of Krakatoa in 1883.
That explosive eruption ejected into the atmosphere more than 25 cubic kilometers of rock, dust and ash and its sound was heard more than 3,000 miles away. As ash and dust circumnavigated the globe, average temperatures declined in many areas for several years and it created optical atmospheric effects such as spectacular, deeply colorful sunsets and “blue” moons.
(Some suggest the blood-red sky shown in Edvard Munch's famous 1893 painting “The Scream” is an accurate depiction of the sky over Norway after the eruption. Munch said: "suddenly the sky turned blood red ... I stood there shaking with fear and felt an endless scream passing through nature.")
An Apophis-sized asteroid impact would be exponentially more devastating than Krakatoa, not only because of the possibility of a dry-land impact in a populated area, but more so due to the massive quantities of dust and dirt which would be lifted into the atmosphere and the resultant “nuclear winter” as the clouds blocked sunlight for months. An ocean impact would create massive tsunamis with destructive forces unlike anything mankind can imagine.
(To more fully imagine the consequences of nuclear winter, read Cormac McCarthy's 2006 novel The Road, which offers a chilling glimpse of post-apocalyptic life on Earth for the survivors of an undefined catastrophe.)
We'll get a couple more shots at refining our calculations. Apophis and Earth get together again observationally in 2013 and 2021, which scientists hope will give them enough data to conclude with even more accuracy than the current 99.9978 percent likelihood a 2036 impact scenario can be ruled out. That 0.0022 percent chance – one in 45,000 – of collision cannot be eliminated until after the gravitational effects of the 2029 close encounter are more reliably defined.
Perhaps more fittingly than can be comprehended by human minds, April 13, 2036 will be Easter Sunday, the day hundreds of millions of Christians celebrate the believed resurrection of Jesus of Nazareth that is the basis of their faith.
Christians expectantly have been waiting through the ages for Jesus to return, the “second coming” prophesied to usher in a thousand-year kingdom of God on Earth. If Jesus arrives with Apophis in fewer than 30 years, he may find little left over which to reign.