This came out recently, althoughthis asteroid has been known about for several years. It really comes astonishingly close to theEarth and is a very plausible impactor since it generally shares our own orbit.
This close encounter will perhapsremove from the at risk window although my own intuition is that it will likelyconverge on a tighter and tighter orbit over many such orbits.
The Russians have decided to goout on a limb and declare that this asteroid could well be as dangerous as itlooks on its second pass in 2036.
How anyone could predict that itwill likely break up, without knowing its constitution escapes me.
It is as dangerous as it looks ifwe have converging orbits and we do not have enough information to know if thismay be true. As reported their modelsbecome rather fussy far too quickly.
I also do not think that the Russianmodels are any better than we have.
Astronomers now predict killer asteroid will hit Earth in 2036
According to "Ria Novosti" in a Jan. 26, 2011 story, Russianastronomers have predicted that an asteroid may impact Earth on Friday, April13, 2036.
But first, the asteroid named "Apophis" will transit within37,000 to 38,000 kilometers (about 23,000 miles) on April 13, 2029. During thattime there is a very small possibility that Apophis could possibly pass througha gravitational keyhole that would generate specific effects which could resultin an actual collision with Earth's surface in 2036. At present, the National Aeronautics and Space Admin. evaluates thispossibility at 1 in 250,000 (4 in a million) and that is a probability of zeroon the TorinoScale.
The operative term for this report is "may." The astronomer,Professor Leonid Sokolov of the St. Petersburg State University
There are some astronomers and observers who consider it possible thatthe 2029 transit by Apophis could be as close as 18,300 miles and that thiswould alter the subsequent orbit enough to vastly increase the possibility ofan impact trajectory with Earth in 2036. As a result, the Russians and theEuropean Space Agency may look into the need for and the possibility ofmanufacturing some space device to divert this asteroid.
In 2013, Apophis will pass within 14,400,000 million km (about 8.9million miles) and astronomers will be able to get more precise measurements topredict the 2029 and 2036 transits, according to "USA Today."
The overall accuracy of identifying these near Earth objects andpredicting their orbits contains large margins of error. On Jan. 13, 2011,"RIA Novosti" reported an object passed within 130,000 km (80,796miles) of Earth. Named "2010 AL30 . . . 'The asteroid posed no dangeranyway,' said astronomer Leonid Yelenin from the Moscow-based Keldysh Instituteof Applied Mathematics. He classified asteroids of over 100 meters in diameteras being dangerous." The article goes on, "Yelenin also said thecalculations were not quite exact: the asteroid that was expected to comeclosest to Earth at about 12:48 GMT did so at 06:45 GMT."
For Apophis, there are two functions that may affect its position andpotential danger, and both processes can be applied to all near Earth objects.The first is "orbital resonance"; the second is the "Yarkovskyeffect."
Orbital resonance is the result of two bodies in space that exertgravitational forces on each other in a certain ratio. This can generate anunstable orbit where they shift positions to eliminate the resonance. The Wikipediaexplanation is useful in this context. Whether this may apply to Apophis hasnot been determined and it has been identified as worth studying by NASA.
The Yarkovsky effect is caused by differences in temperatures on thesunny side and the dark side of objects in space. The JetPropulsion Laboratories explanation is an easy-to-read article thatdemonstrates how this could change the orbit of Apophis.
Because of these various effects, Apophis will be the subject of closeobservation in 2013 as NASA, the European Space Agency and Russian astronomerskeep track of it and other potentially dangerous near Earth objects.
Russian astronomers have predicted that asteroid Apophis may strikeEarth on April 13, 2036.
"Apophis will approach Earth at a distance of 37,000-38,000kilometers on April 13, 2029. Its likely collision with Earth may occur onApril 13, 2036," Professor Leonid Sokolov of the St. Petersburg State University
The scientist said, however, the chance of a collision in 2036 wasextremely slim saying that the asteroid would likely disintegrate into smallerparts and smaller collisions with Earth could occur in the following years.
"Our task is to consider various alternatives and developscenarios and plans of action depending on the results of further observationsof Apophis," Sokolov said.
The asteroid, discovered in 2004, is considered the largest threat toour planet, although NASA scientists reduced the likelihood of a hazardousstrike with Earth in 2036.
Friday the 13th, 2029
Asteroid 2004 MN4 will come scarily close to Earth on April 13, 2029,but it will not hit.
May 13, 2005: Friday the 13th is supposed to be an unlucky day,the sort of day you trip on your shoe laces or lose your wallet or get badnews.
But maybe it's not so bad. Consider this: On April 13th--Friday the13th--2029, millions of people are going to go outside, look up and marvel attheir good luck. A point of light will be gliding across the sky, faster thanmany satellites, brighter than most stars.
What's so lucky about that? It's asteroid 2004 MN4 ... not hittingEarth.
Fora while astronomers thought it might. On Christmas Eve 2004, Paul Chodas, SteveChesley and Don Yeomans at NASA's Near Earth Object Program office calculated a1-in-60 chance that 2004 MN4 would collide with Earth. Impact date: April 13,2029.
Right: The orbits of Earth and asteroid 2004 MN4. [More]
The asteroid is about 320 meters wide. "That's big enough to punchthrough Earth's atmosphere," devastating a region the size of, say, Texas,if it hit land, or causing widespread tsunamis if it hit ocean, says Chodas. Somuch for holiday cheer.
Asteroid 2004 MN4 had been discovered in June 2004, lost, thendiscovered again six months later. With such sparse tracking data it wasdifficult to say, precisely, where the asteroid would go. A collision withEarth was theoretically possible. "We weren't too worried," Chodassays, "but the odds were disturbing."
This is typical, by the way, of newly-discovered asteroids. Step 1: Anasteroid is discovered. Step 2: Uncertain orbits are calculated from spottytracking data. Step 3: Possible Earth impacts are noted. Step 4: Astronomerswatch the asteroid for a while, then realize that it's going to miss ourplanet.
Killer Asteroid! headlines generally appear between steps 3 and 4,but that's anotherstory.
Astronomers knew 2004 MN4 would miss Earth when they found pictures ofthe asteroid taken, unwittingly, in March 2004, three months before itsofficial discovery. The extra data ruled out a collision in 2029.
Instead, what we're going to have is an eye-popping close encounter:
On April 13, 2029, asteroid 2004 MN4 will fly past Earth only 18,600miles (30,000 km) above the ground. For comparison, geosynchronous satellitesorbit at 22,300 miles (36,000 km). "At closest approach, the asteroid willshine like a 3rd magnitude star, visible to the unaided eye from Africa, Europeand Asia --even through city lights," saysJon Giorgini of JPL. This is rare. "Close approaches by objects as largeas 2004 MN4 are currently thought to occur at 1000-year intervals, onaverage."
Above: The trajectory (blue) of asteroid 2004 MN4 past Earth onApril 13, 2029. Uncertainty in the asteroid's close-approach distance isrepresented by the short white bar. [More]
The asteroid's trajectory will bend approximately 28 degrees during theencounter, "a result of Earth's gravitational pull," explainsGiorgini. What happens next is uncertain. Some newspapers have stated that theasteroid might swing around and hit Earth after all in 2035 or so, but Giorginidiscounts that: "Our ability to 'see' where 2004 MN4 will go (byextrapolating its orbit) is so blurred out by the 2029 Earth encounter, itcan't even be said for certain what side of the sun 2004 MN4 will be on in2035. Talk of Earth encounters in 2035 is premature."
In January 2004, a team of astronomers led by Lance Benner of JPLpinged 2004 MN4 using the giant Arecibo radar inPuerto Rico . (Coincidentally, the Arecibo
More data are needed to forecast 2004 MN4's motion beyond 2029."The next good opportunities are in 2013 and 2021," Giorgini says.The asteroid will be about 9 million miles (14 million km) from Earth, invisibleto the naked eye, but close enough for radar studies. "If we get radarranging in 2013, we should be able to predict the location of 2004 MN4 out toat least 2070."
The closest encounter of all, Friday the 13th, 2029, will be aspectacular opportunity to explore this asteroid via radar. During thisencounter, says Giorgini, "radar could detect the distortion of 2004 MN4'sshape and spin as it passes through Earth's gravity field. How the asteroidchanges (or not) would provide information about its internal structure andmaterial composition." Beautifully-detailed surface maps are possible,too.
The view through an optical telescope won't be so impressive. Theasteroid's maximum angular diameter is only 2 to 4 arcseconds, which means itwill be a starlike point of light in all but the very largest telescopes.
But to the naked eye--wow! No one in recorded history has ever seen anasteroid in space so bright.
Friday the 13th might not be so bad after all.
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