How big would an asteroid have to be to wipe out all life on Earth?
By Marsha Lewis, Contributing Producer, Inside ScienceUpdated
Artist's concept of a catastrophic asteroid impact with the early Earth.NASA/Don Davis
GALLERY: Asteroids and meteors we have known
In this photo provided by Chelyabinsk.ru a meteorite contrail is seen over Chelyabinsk on Friday, Feb. 15, 2013. A meteor streaked across the sky of Russia's Ural Mountains on Friday morning, causing sharp explosions and reportedly injuring around 100 people, including many hurt by broken glass.Photo/Chelyabinsk.ru
This photo provided by The Field Museum in Chicago, taken April 9, 2013, shows pieces of a meteor that exploded over Russia's Ural Mountains in February after they were catalogued on their arrival at the Chicago museum. The museum received nearly two pounds of small meteorite pieces donated by a collector. After a surprise meteor hit Earth at 42,000 mph and exploded over a Russian city in February, smashing windows and causing minor injuries, scientists studying the aftermath say the threat of space rocks hurtling toward our planet is bigger than they had thought. Meteors like the one that exploded over Chelyabinsk _ and those that are even bigger and more dangerous _ are probably four to five times more likely to hit Earth than scientists thought before the February mid-air explosion, according to three studies released Wednesday in the journals Nature and Science.Karen Bean/ASSOCIATED PRESS
The is an up-to-date map of the solar system displaying the orbits of the terrestrial planets and the estimated position of thousands of known asteroids. This diagram is missing comets, space probes and, of course, the undiscovered asteroids. Even conservative estimates would suggest that for every asteroid on a dangerous Earth-Approaching orbit there are hundreds more which have yet to be discovered. There are over 300 known objects on Earth-crossing orbits, the majority of which are potentially capable of causing death and destruction on a scale unheard of in human history. Computer-generated image via Scott Manley at Armagh Observatory
In this frame grab made from a video done with a dashboard camera a meteor streaks through the sky over Chelyabinsk, about 1500 kilometers (930 miles) east of Moscow, Friday, Feb. 15, 2013. A meteor that scientists estimate weighed 10 tons (11 tons) streaked at supersonic speed over Russia's Ural Mountains on Friday, setting off blasts that injured some 500 people and frightened countless more. (AP Photo/AP Video)
A circular hole in the ice of Chebarkul Lake where a meteor reportedly struck the lake near Chelyabinsk, about 1500 kilometers (930 miles) east of Moscow, Russia, Friday, Feb. 15, 2013. A meteor streaked across the sky and exploded over Russia's Ural Mountains with the power of an atomic bomb Friday, its sonic blasts shattering countless windows and injuring nearly 1,000 people.Associated Press
Men look in Moscow on October 16, 2013, at a computer screen displaying a team of divers pulling out a 1.5-metre-long (five-foot-long) suspected meteorite wrapped it in a special casing from the lake Chebarkul in the Chelyabinsk region. Russian divers pulled today from a murky lake in the Urals a half-tonne suspected meteorite said to have been part of a meteor whose ground-shaking shockwave hurt 1,200 people in February.AFP PHOTO / STR/Getty Images
Meteor Crater is one of the youngest and best-preserved impact craters on Earth. The crater formed roughly 50,000 years ago when a 30-meter-wide, iron-rich meteor weighing 100,000 tons struck the Arizona desert at an estimated 20 kilometers per second. The resulting explosion exceeded the combined force of today's nuclear arsenals and created a 1.1-kilometer-wide, 200-meter-deep crater. Meteor Crater is a simple crater since it has no central peak or rim terraces. The crater formed in layered Paleozoic age sedimentary rocks, some of which are exposed in the nearby Grand Canyon. These rocks have been uplifted and in some cases overturned at the crater's raised rim. Debris sliding and subsequent erosion have partially filled the bottom of the crater with minor amounts of rim material and sediment. The heavily cratered history of the Moon indicates that Earth also experienced many impact events early in its history. The processes of erosion and plate tectonics have combined to erase nearly all Earth's craters. To date, only about 150 impact craters have been identified on Earth, and most of those are severely eroded or buried by later rock units. The origin of this classic, simple meteorite impact crater was long the subject of controversy. The discovery of fragments of the Canyon Diablo meteorite, including fragments within the breccia deposits that partially fill the structure, and a range of shock metamorphic features in the target sandstone proved its impact origin. Target rocks include Paleozoic carbonates and sandstones; these rocks were overturned just outside the rim during ejection. The hummocky deposits just beyond the rim are remnants of the ejecta blanket. This aerial view shows the dramatic expression of the crater in the arid landscape. The crater is named for Daniel Moreau Barringer, a mining...NASA/SSPL/Getty Images
In this 1953 file photo, trees lie strewn across the Siberian countryside 45 years after a meteorite struck the Earth near Tunguska, Russia. The 1908 explosion is generally estimated to have been about 10 megatons; it leveled some 80 million trees for miles near the impact site. The meteor that streaked across the Russian sky Friday, Feb. 15, 2013, is estimated to be about 10 tons. It exploded with the power of an atomic bomb over the Ural Mountains, about 5,000 kilometers (3,000 miles) west of Tunguska.Associated Press
Rim of the Barringer Meteor Crater near Winslow, Arizona.Independent Picture Service/UIG via Getty Images
Manicouagan Crater, The Manicouagan Reservoir Crater In Quebec, Canada, Is One Of The Largest Meteorite Craters In The World, It Was Formed When The Earth Was Blasted By A Giant Meteorite At The End Of The Triassic Period Some 210 Million Years Ago.
NASA imagines the asteroid that killed the dinosaurs as it breaks up in the asteroid belt and heads for Earth.
A view of the wall of a local zinc plant which was damaged by a shockwave from a meteor in the Urals city of Chelyabinsk, on February 15, 2013. A meteor strike in central Russia that left today hundreds of people injured is the biggest known human toll from a space rock, a British expert said.AFP PHOTO / 74.RU/ OLEG KARGOPOLOV
In this photo provided by E1.ru a meteorite contrail is seen over a vilage of Bolshoe Sidelnikovo 50 km of Chelyabinsk on Friday, Feb. 15, 2013. A meteor streaked across the sky of Russia's Ural Mountains on Friday morning, causing sharp explosions and reportedly injuring around 100 people, including many hurt by broken glass.AP Photo/ Nadezhda Luchinina, E1.ru
In this photo taken with a mobile phone camera, a meteorite contrail is seen in Chelyabinsk region on Friday, Feb. 15, 2013. A meteor streaked across the sky of Russia's Ural Mountains on Friday morning, causing sharp explosions and reportedly injuring around 100 people, including many hurt by broken glass.AP Photo/Sergey Hametov
A meteorite trail is seen above a residential apartment block in the Urals city of Chelyabinsk, on February 15, 2013. A heavy meteor shower rained down today on central Russia, sowing panic as the hurtling space debris smashed windows and injured dozens of stunned locals, officials said.AFP PHOTO / 74.RU/ OLEG KARGOPOLOV Photo: AFP, Getty Images
People stand in front of the facade of a local shop which was damaged by a shockwave from a meteor in the Urals city of Chelyabinsk, on February 15, 2013. A meteor strike in central Russia that left today hundreds of people injured is the biggest known human toll from a space rock, a British expert said.AFP, Getty Images
A view of the facade of a local paint and varnish plant which was damaged by a shockwave from a meteor in the Urals city of Chelyabinsk, on February 15, 2013. A meteor strike in central Russia that left today hundreds of people injured is the biggest known human toll from a space rock, a British expert said.AFP, Getty Images
Graphic depicts the trajectory of asteroid 2012 DA14 on Feb 15, 2013. In this view, we are looking down from above Earth's north pole. NASA/JPL-Caltech
Graphic depicts the trajectory of asteroid 2012 DA14 during its close approach, as seen edge-on to Earth's equatorial plane. The graphic demonstrates why the asteroid is invisible to northern hemisphere observers until just before close approach: it is approaching from underneath our planet. On the other hand, after close approach it will be favorably placed for observers in the northern hemisphere.NASA/JPL-Caltech
Dawn mission data has revealed the rugged topography and complex textures of the asteroid Vesta's surface. Soon other pieces of data such as the chemical composition, interior structure, and geologic age will help scientists understand the history of this remnant protoplanet and its place in the early solar system. After a year orbiting Vesta, the Dawn spacecraft will depart in July 2012 for the dwarf planet Ceres, where it will arrive in 2015.NASA
The south pole of the giant asteroid Vesta, as imaged by the framing camera on NASA's Dawn spacecraft in September 2011.NASA
Artist rendition of asteroid Vesta.NASA
Just another streak in the sky.
Artist's concept of a catastrophic asteroid impact with the early Earth.NASA/Don Davis
(Inside Science TV) -- Ever wonder how big an asteroid would have to be to wipe out life on the planet?
Turns out about 60 miles wide.
Scientists have been looking at potential asteroid impacts for years.
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University of Colorado Boulder, geoscientist Brian Toon figures one rock about a half a mile wide can do a lot of damage and cause widespread Earthquakes, releasing the energy equal to 100 billion tons of TNT.
But even that wouldn't be completely catastrophic. Scientists think the object that may have hastened the death of the dinosaurs was about seven to eight miles wide, sending a dust plume so big it engulfed the planet, igniting fires and basically broiling the dinosaurs.
A similar collision today would likely kill billions of people ... most of the animals and all the vegetation. It's possible a few people could survive but they would have a hard time finding food.
Richard Binzel, a professor of planetary sciences at MIT says even though it's possible this could happen someday, there are no asteroids big enough in any orbit that can completely destroy Earth.
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What would happen if a smaller asteroid, one the size of a house, crashed into Earth at 30,000 miles per hour? Experts say it would flatten concrete buildings up to a half mile from where it hit.
What if the asteroid was the size of a 20-story building? It would flatten all the buildings within five miles.
The next near Earth asteroid will make its closest approach on October 26th, 2028. The asteroid's path is predicted to pass beyond the Moon's distance from the Earth. In fact, it will still be about two and half times farther away from the Earth than the Moon. It measures a mile-wide and is traveling at a speed of 30-thousand miles per hour. If it did strike New York City, the force would flatten everything from D.C. to Boston.
But not to worry – NASA says it will have zero impact on Earth.
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To help keep us all safe from any possible future asteroids – NASA is developing an asteroid re-direct mission. It's a first-of-its-kind mission for a spacecraft to land on a large asteroid, grab a huge boulder from its surface for further study and then re-direct the asteroid into a stable orbit around the Moon. This mission is set to launch by 2020.
Marsha Lewis is a freelance producer based in California. She has won 11 National Telly Awards and nine Regional Emmy Awards for her work in local and national syndicated news.
Reprinted with permission from Inside Science, an editorially independent news product of the American Institute of Physics, a nonprofit organization dedicated to advancing, promoting and serving the physical sciences.
