Asteroid buzzes Earth, will be back

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In September, a large asteroid passed close by our planetThe asteroid, 2013 TV135, was discovered this monthNASA says there is very little chance of it posing a threat to EarthSomeday a massive asteroid will wreak havoc on Earth, but that is likely millions of years away

(CNN) -- One of the most dangerous asteroids on record zipped close by Earth last month.

It made headlines on Thursday, when reports said that there's a chance it could strike our planet in less than 20 years. Such a collision could unleash a force as powerful as a couple of thousand atomic bombs.

But NASA was quick to calm nerves and point out some very good news. The most dangerous known asteroids don't really pose much of a threat. And there are very few of them.

Also, the chances that this one, which the Ukrainian astronomers who discovered it named 2013 TV135, will collide with Earth are extremely slim, NASA said in a statement it called "a reality check."

The space agency is 99.998% certain that when it whooshes back around the planet in 2032, it will simply sail past us again.

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A diagram shows the orbit of an asteroid named 2013 TV135 (in blue), which made headlines in September 2013 when it passed closely by Earth. The probability of it striking Earth currently stands at 1 in 63,000, and even those odds are fading fast as scientists find out more about the asteroid. It will most likely swing past our planet again in 2032, according to NASA.cnnArticleGallery.currentImageList[cnnArticleGallery.currentImageList.length] = {"currentPicture":true,"x":6,"y":1,"pos":1,"title":"All about asteroids"}

Asteroid 1998 QE2 about 3.75 million miles from Earth. The white dot is the moon, or satellite, orbiting the asteroid.cnnArticleGallery.currentImageList[cnnArticleGallery.currentImageList.length] = {"currentPicture":false,"x":6,"y":1,"pos":2,"title":"All about asteroids"}

Asteroid 2012 DA14 made a record-close pass -- 17,100 miles -- by Earth on February 15. Most asteroids are made of rocks, but some are metal. They orbit mostly between Jupiter and Mars in the main asteroid belt. Scientists estimate there are tens of thousands of asteroids and when they get close to our planet, they are called near-Earth objects.cnnArticleGallery.currentImageList[cnnArticleGallery.currentImageList.length] = {"currentPicture":false,"x":6,"y":1,"pos":3,"title":"All about asteroids"}

Another asteroid, Apophis, got a lot of attention from space scientists and the media when initial calculations indicated a small chance it could hit Earth in 2029 or 2036. NASA scientists have since ruled out an impact, but on April 13, 2029, Apophis, which is about the size of 3½ football fields, will make a close visit -- flying about 19,400 miles (31,300 kilometers) above Earth's surface. The images above were taken by the European Space Agency's Herschel Space Observatory in January 2013.cnnArticleGallery.currentImageList[cnnArticleGallery.currentImageList.length] = {"currentPicture":false,"x":6,"y":1,"pos":4,"title":"All about asteroids"}

If you really want to know about asteroids, you need to see one up close. NASA did just that. A spacecraft called NEAR-Shoemaker, named in honor of planetary scientist Gene Shoemaker, was the first probe to touch down on an asteroid, landing on the asteroid Eros on February 12, 2001. This image was taken on February 14, 2000, just after the probe began orbiting Eros.cnnArticleGallery.currentImageList[cnnArticleGallery.currentImageList.length] = {"currentPicture":false,"x":6,"y":1,"pos":5,"title":"All about asteroids"}

The first asteroid to be identified, 1 Ceres, was discovered January 1, 1801, by Giuseppe Piazzi in Palermo, Sicily. But is Ceres just another asteroid? Observations by NASA's Hubble Space Telescope show that Ceres has a lot in common with planets like Earth. It's almost round and it may have a lot of pure water ice beneath its surface. Ceres is about 606 by 565 miles (975 by 909 kilometers) in size and scientists say it may be more accurate to call it a mini-planet. NASA's Dawn spacecraft is on its way to Ceres to investigate. The spacecraft is 35 million miles (57 million kilometers) from Ceres and 179 million miles (288 million kilometers) from Earth. The photo on the left was taken by Keck Observatory, Mauna Kea, Hawaii. The image on the right was taken by the Hubble Space Telescope.cnnArticleGallery.currentImageList[cnnArticleGallery.currentImageList.length] = {"currentPicture":false,"x":6,"y":1,"pos":6,"title":"All about asteroids"}

One big space rock got upgraded recently. This image of Vesta was taken by the Dawn spacecraft, which is on its way to Ceres. In 2012, scientists said data from the spacecraft show Vesta is more like a planet than an asteroid and so Vesta is now considered a protoplanet.cnnArticleGallery.currentImageList[cnnArticleGallery.currentImageList.length] = {"currentPicture":false,"x":6,"y":1,"pos":7,"title":"All about asteroids"}

The three-mile long (4.8-kilometer) asteroid Toutatis flew about 4.3 million miles (6.9 million kilometers) from Earth on December 12, 2012. NASA scientists used radar images to make a short movie.cnnArticleGallery.currentImageList[cnnArticleGallery.currentImageList.length] = {"currentPicture":false,"x":6,"y":1,"pos":8,"title":"All about asteroids"}

Asteroids have hit Earth many times. It's hard to get an exact count because erosion has wiped away much of the evidence. The mile-wide Meteor Crater in Arizona, seen above, was created by a small asteroid that hit about 50,000 years ago, NASA says. Other famous impact craters on Earth include Manicouagan in Quebec, Canada; Sudbury in Ontario, Canada; Ries Crater in Germany, and Chicxulub on the Yucatan coast in Mexico. cnnArticleGallery.currentImageList[cnnArticleGallery.currentImageList.length] = {"currentPicture":false,"x":6,"y":1,"pos":9,"title":"All about asteroids"}

NASA scientists say the impact of an asteroid or comet several hundred million years ago created the Aorounga crater in the Sahara Desert of northern Chad. The crater has a diameter of about 10.5 miles (17 kilometers). This image was taken by the Space Shuttle Endeavour in 1994.cnnArticleGallery.currentImageList[cnnArticleGallery.currentImageList.length] = {"currentPicture":false,"x":6,"y":1,"pos":10,"title":"All about asteroids"}

In 1908 in Tunguska, Siberia, scientists theorize an asteroid flattened about 750 square miles (1,200 square kilometers) of forest in and around the Podkamennaya Tunguska River in what is now Krasnoyarsk Krai, Russia.cnnArticleGallery.currentImageList[cnnArticleGallery.currentImageList.length] = {"currentPicture":false,"x":6,"y":1,"pos":11,"title":"All about asteroids"}

What else is up there? Is anyone watching? NASA's Near-Earth Object Program is trying to track down all asteroids and comets that could threaten Earth. NASA says 9,672 near-Earth objects have been discovered as of February 5, 2013. Of these, 1,374 have been classified as Potentially Hazardous Asteroids, or objects that could one day threaten Earth.cnnArticleGallery.currentImageList[cnnArticleGallery.currentImageList.length] = {"currentPicture":false,"x":6,"y":1,"pos":12,"title":"All about asteroids"}

One of the top asteroid-tracking scientists is Don Yeomans at the Jet Propulsion Laboratory, which is managed by the California Institute of Technology. Yeomans says every day, "Earth is pummeled by more than 100 tons of material that spewed off asteroids and comets." Fortunately, most of the asteroid trash is tiny and it burns up when it hits the atmosphere, creating meteors, or shooting stars. Yeomans says it's very rare for big chunks of space litter to hit Earth's surface. Those chunks are called meteorites. cnnArticleGallery.currentImageList[cnnArticleGallery.currentImageList.length] = {"currentPicture":false,"x":6,"y":1,"pos":13,"title":"All about asteroids"}

Asteroids and comets are popular fodder for Earth-ending science fiction movies. Two of the biggest blockbusters came out in 1998: "Deep Impact" and "Armageddon." (Walt Disney Studios) Others include "Meteorites!" (1998), "Doomsday Rock" (1997), "Asteroid" (1997), "Meteor" (1979), and "A Fire in the Sky" (1978). Can you name others?cnnArticleGallery.currentImageList[cnnArticleGallery.currentImageList.length] = {"currentPicture":false,"x":6,"y":1,"pos":14,"title":"All about asteroids"}

Photos: All about asteroids var currExpandable="expand26";if(typeof CNN.expandableMap==='object'){CNN.expandableMap.push(currExpandable);}var mObj={};mObj.type='video';mObj.contentId='';mObj.network='cnnintl';mObj.source='international/2013/06/29/exp-nasas-asteroid-grand-challenge.cnn';mObj.videoSource='CNN';mObj.videoSourceUrl='';mObj.lgImage="http://i2.cdn.turner.com/cnn/dam/assets/130630145030-exp-nasas-asteroid-grand-challenge-00011013-story-body.jpg";mObj.lgImageX=300;mObj.lgImageY=169;mObj.origImageX="214";mObj.origImageY="120";mObj.contentType='video';CNN.expElements.expand26Store=mObj;var currExpandable="expand36";if(typeof CNN.expandableMap==='object'){CNN.expandableMap.push(currExpandable);}var mObj={};mObj.type='video';mObj.contentId='';mObj.network='cnnintl';mObj.source='bestoftv/2013/06/19/exp-erin-the-number-nasa-launches-grand-asteroid-challenge.cnn';mObj.videoSource='CNN';mObj.videoSourceUrl='http://outfront.blogs.cnn.com/ ';mObj.lgImage="http://i2.cdn.turner.com/cnn/dam/assets/130531100431-asteroid-story-body.jpg";mObj.lgImageX=300;mObj.lgImageY=169;mObj.origImageX="214";mObj.origImageY="120";mObj.contentType='video';CNN.expElements.expand36Store=mObj;var currExpandable="expand46";if(typeof CNN.expandableMap==='object'){CNN.expandableMap.push(currExpandable);}var mObj={};mObj.type='video';mObj.contentId='';mObj.network='cnnintl';mObj.source='bestoftv/2013/10/16/pkg-russia-meteorite.cnn';mObj.videoSource='CNN';mObj.videoSourceUrl='';mObj.lgImage="http://i2.cdn.turner.com/cnn/dam/assets/131016190019-pkg-russia-meteorite-00000902-story-body.jpg";mObj.lgImageX=300;mObj.lgImageY=169;mObj.origImageX="214";mObj.origImageY="120";mObj.contentType='video';CNN.expElements.expand46Store=mObj;The probability of it striking Earth currently stands at 1:63,000, and even those odds are fading fast, as scientists find out more about the asteroid.

"This is a relatively new discovery," said Don Yeomans, manager of NASA's NEO Program. "With more observations, I fully expect we will be able to significantly reduce, or rule out entirely, any impact probability for the foreseeable future."

2013 TV135 was discovered on October 8, while NASA was closed during the government shutdown. And already it looks to soon be joining the ranks of the more than 10,000 known near-Earth objects that are virtually certain to cause us no harm.

But until then, it has the distinction of having a danger rating of 1 out of a possible 10 on the Torino Impact Hazard Scale, the system that gauges the danger of impact destruction by asteroids.

The 1 rating means that it poses "no unusual level of danger." There is "no cause for public attention or concern."

Almost all other asteroids that scientists have discovered rank a 0 on the scale. There is another asteroid with a danger rating of 1. And it, too, is no cause for alarm, NASA says.

September's close pass

The close pass 2013 TV135 made on September 16 was not a near miss. At a distance of 4.2 million miles as it flew by, it was more than 15 times as far away from Earth as the moon.

That pales by compare to the closest shave the Earth got from an asteroid of considerable size in recorded history.

On February 15 this year, asteroid 2012 DA14, which measured 150 feet wide, slipped in below the moon's orbit and squeaked by our planet just 17,200 miles from its surface.

The one that passed by in September is big, with a diameter of 1,300 feet. That's the size of four football fields, but it does not quite make it an Earth crusher.

An asteroid needs to be at least twice as large to advance into that league.

"We believe anything larger than one to two kilometers (about 0.6 to 1.2 miles) could have worldwide effects," NASA said in a statement.

Russian divers find huge suspected meteorite chunk

Near passes daily

Two behemoths in that size range will pass by planet Earth in the next three months at similar distances as 2013 TV135. NASA says that neither will hit us.

Near asteroid passes are common. They pretty much occur daily, if not two or three times a day, NASA says.

They come, and they go, and they leave the Earth in peace.

In addition, particles from space bombard our planet every minute -- at a rate of 100 tons a day, NASA says.

You eat them; you drink them; you breathe them. Much of you and everything else on Earth contains them.

Distant catastrophe

Though it seems Earth is safe for now, there is such a thing as a doomsday asteroid.

Scientists say it is likely that the impact of an asteroid over six miles wide wiped out dinosaurs along with much of the life on Earth 65 million years ago.

More like it will come, NASA says.

But they only turn up once every "few million years."

That may give humanity some time to find a way of dealing with it.

Follow @CNNLightYears on Twitter for more science news updates

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October 18, 2013 -- Updated 2042 GMT (0442 HKT)

One of the most dangerous asteroids on record zipped close by Earth in September. June 2, 2013 -- Updated 1532 GMT (2332 HKT)

The world is OK -- at least this time -- and scientists are psyched.February 16, 2013 -- Updated 0425 GMT (1225 HKT)

It was hardly a doomsday event, but at 2:24 p.m. ET, an asteroid came pretty close to Earth. nasa asteroide

Dr. Bruce Betts of the Planetary Society, the world's largest space interest group, says this could be more common than most might think.

The meteorite in Russia and the asteroid approaching are "completely unrelated," according to NASA. The trajectory of the meteorite differs substantially from asteroid 2012 DA14.

Don Yeomans spends his days monitoring the thousands of asteroids and comets swirling around the solar system, making sure that none of the bigger ones are on a collision course with Earth.

In the future, scientists want to be able to send spacecraft to study asteroids such as the one that will approach the Earth on Friday. A concept for these landers may look familiar to anyone who grew up in the 1970s.February 8, 2013 -- Updated 1041 GMT (1841 HKT)

Don't consider this a count-down to doomsday, but on February 15 an asteroid is going to come pretty close to Earth.

The nonprofit B612 Foundation plans to raise money to build an infrared space telescope that would find and track asteroids with enough accuracy to see if they would collide with Earth.October 18, 2013 -- Updated 1733 GMT (0133 HKT)

Scientists estimate there are tens of thousands of asteroids. Click through our gallery of asteroids to learn more. February 13, 2013 -- Updated 1625 GMT (0025 HKT)

Former NASA astronaut Ed Lu is building a space telescope to detect asteroids that could hit earth in our lifetime.January 25, 2013 -- Updated 1126 GMT (1926 HKT)

Scoping out space rocks for mining metals just became a two-horse race. Hala Gorani reports.January 24, 2013 -- Updated 2256 GMT (0656 HKT)

Space, it has been said, is big. Really big. So how do we mine its potential?January 24, 2013 -- Updated 1346 GMT (2146 HKT)

Look up at our nearest neighbor, the moon, and you'll see stark evidence of the dangerous neighborhood we live in. The Man in the Moon was sculpted by large-scale events, including many meteor and asteroid impacts.December 24, 2012 -- Updated 1012 GMT (1812 HKT)

On a day when global doomsday predictions failed to pan out, NASA had more good news for the Earth: An asteroid feared to be on a collision course with our planet no longer poses a threat.