This came out recently, although
this asteroid has been known about for several years. It really comes astonishingly close to the
Earth and is a very plausible impactor since it generally shares our own orbit.
This close encounter will perhaps
remove from the at risk window although my own intuition is that it will likely
converge on a tighter and tighter orbit over many such orbits.
The Russians have decided to go
out on a limb and declare that this asteroid could well be as dangerous as it
looks on its second pass in 2036.
How anyone could predict that it
will likely break up, without knowing its constitution escapes me.
It is as dangerous as it looks if
we have converging orbits and we do not have enough information to know if this
may be true. As reported their models
become rather fussy far too quickly.
I also do not think that the Russian
models 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, Russian
astronomers have predicted that an asteroid may impact Earth on Friday, April
13, 2036.
But first, the asteroid named "Apophis" will transit within
37,000 to 38,000 kilometers (about 23,000 miles) on April 13, 2029. During that
time there is a very small possibility that Apophis could possibly pass through
a gravitational keyhole that would generate specific effects which could result
in an actual collision with Earth's surface in 2036. At present, the National Aeronautics and Space Admin. evaluates this
possibility at 1 in 250,000 (4 in a million) and that is a probability of zero
on the Torino
Scale.
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 that
the 2029 transit by Apophis could be as close as 18,300 miles and that this
would alter the subsequent orbit enough to vastly increase the possibility of
an impact trajectory with Earth in 2036. As a result, the Russians and the
European Space Agency may look into the need for and the possibility of
manufacturing some space device to divert this asteroid.
In 2013, Apophis will pass within 14,400,000 million km (about 8.9
million miles) and astronomers will be able to get more precise measurements to
predict the 2029 and 2036 transits, according to "USA Today."
The overall accuracy of identifying these near Earth objects and
predicting their orbits contains large margins of error. On Jan. 13, 2011,
"RIA Novosti" reported an object passed within 130,000 km (80,796
miles) of Earth. Named "2010 AL30 . . . 'The asteroid posed no danger
anyway,' said astronomer Leonid Yelenin from the Moscow-based Keldysh Institute
of Applied Mathematics. He classified asteroids of over 100 meters in diameter
as being dangerous." The article goes on, "Yelenin also said the
calculations were not quite exact: the asteroid that was expected to come
closest to Earth at about 12:48 GMT did so at 06:45 GMT."
For Apophis, there are two functions that may affect its position and
potential danger, and both processes can be applied to all near Earth objects.
The first is "orbital resonance"; the second is the "Yarkovsky
effect."
Orbital resonance is the result of two bodies in space that exert
gravitational forces on each other in a certain ratio. This can generate an
unstable orbit where they shift positions to eliminate the resonance. The Wikipedia
explanation is useful in this context. Whether this may apply to Apophis has
not been determined and it has been identified as worth studying by NASA.
The Yarkovsky effect is caused by differences in temperatures on the
sunny side and the dark side of objects in space. The Jet
Propulsion Laboratories explanation is an easy-to-read article that
demonstrates how this could change the orbit of Apophis.
Because of these various effects, Apophis will be the subject of close
observation in 2013 as NASA, the European Space Agency and Russian astronomers
keep track of it and other potentially dangerous near Earth objects.
Russian astronomers have predicted that asteroid Apophis may strike
Earth on April 13, 2036.
"Apophis will approach Earth at a distance of 37,000-38,000
kilometers on April 13, 2029. Its likely collision with Earth may occur on
April 13, 2036," Professor Leonid Sokolov of the St. Petersburg State
University
The scientist said, however, the chance of a collision in 2036 was
extremely slim saying that the asteroid would likely disintegrate into smaller
parts and smaller collisions with Earth could occur in the following years.
"Our task is to consider various alternatives and develop
scenarios and plans of action depending on the results of further observations
of Apophis," Sokolov said.
The asteroid, discovered in 2004, is considered the largest threat to
our planet, although NASA scientists reduced the likelihood of a hazardous
strike 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 bad
news.
But maybe it's not so bad. Consider this: On April 13th--Friday the
13th--2029, millions of people are going to go outside, look up and marvel at
their good luck. A point of light will be gliding across the sky, faster than
many satellites, brighter than most stars.
What's so lucky about that? It's asteroid 2004 MN4 ... not hitting
Earth.
For
a while astronomers thought it might. On Christmas Eve 2004, Paul Chodas, Steve
Chesley and Don Yeomans at NASA's Near Earth Object Program office calculated a
1-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 punch
through 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. So
much for holiday cheer.
Asteroid 2004 MN4 had been discovered in June 2004, lost, then
discovered again six months later. With such sparse tracking data it was
difficult to say, precisely, where the asteroid would go. A collision with
Earth was theoretically possible. "We weren't too worried," Chodas
says, "but the odds were disturbing."
This is typical, by the way, of newly-discovered asteroids. Step 1: An
asteroid is discovered. Step 2: Uncertain orbits are calculated from spotty
tracking data. Step 3: Possible Earth impacts are noted. Step 4: Astronomers
watch the asteroid for a while, then realize that it's going to miss our
planet.
Killer Asteroid! headlines generally appear between steps 3 and 4,
but that's another
story.
Astronomers knew 2004 MN4 would miss Earth when they found pictures of
the asteroid taken, unwittingly, in March 2004, three months before its
official 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 18,600
miles (30,000 km) above the ground. For comparison, geosynchronous satellites
orbit at 22,300 miles (36,000 km). "At closest approach, the asteroid will
shine like a 3rd magnitude star, visible to the unaided eye from Africa, Europe
and Asia --even through city lights," says
Jon Giorgini of JPL. This is rare. "Close approaches by objects as large
as 2004 MN4 are currently thought to occur at 1000-year intervals, on
average."
Above: The trajectory (blue) of asteroid 2004 MN4 past Earth on
April 13, 2029. Uncertainty in the asteroid's close-approach distance is
represented by the short white bar. [More]
The asteroid's trajectory will bend approximately 28 degrees during the
encounter, "a result of Earth's gravitational pull," explains
Giorgini. What happens next is uncertain. Some newspapers have stated that the
asteroid might swing around and hit Earth after all in 2035 or so, but Giorgini
discounts that: "Our ability to 'see' where 2004 MN4 will go (by
extrapolating its orbit) is so blurred out by the 2029 Earth encounter, it
can't even be said for certain what side of the sun 2004 MN4 will be on in
2035. Talk of Earth encounters in 2035 is premature."
In January 2004, a team of astronomers led by Lance Benner of JPL
pinged 2004 MN4 using the giant Arecibo radar in
Puerto 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, invisible
to the naked eye, but close enough for radar studies. "If we get radar
ranging in 2013, we should be able to predict the location of 2004 MN4 out to
at least 2070."
The closest encounter of all, Friday the 13th, 2029, will be a
spectacular opportunity to explore this asteroid via radar. During this
encounter, says Giorgini, "radar could detect the distortion of 2004 MN4's
shape and spin as it passes through Earth's gravity field. How the asteroid
changes (or not) would provide information about its internal structure and
material composition." Beautifully-detailed surface maps are possible,
too.
The view through an optical telescope won't be so impressive. The
asteroid's maximum angular diameter is only 2 to 4 arcseconds, which means it
will 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 an
asteroid in space so bright.
Friday the 13th might not be so bad after all.
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