NEO Watch: Two Asteroids Zipping Past Earth Today
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September 08, 2010

NEO Watch: Two Asteroids Zipping Past Earth Today

Two-Asteroids-To-Swing-Past-Earth-Today-2 Experts at a NASA lab have announced that two asteroids discovered on Sunday will pass close to Earth today, September 8. The two space rocks are in unrelated orbits, the team says, and pose no danger to Earth. What's unusual is that they will both zip past the planet the same day, even if they come from very different orbits. Astronomers estimate that the undiscovered population of near earth objects (NEOs) orbiting the solar system in our vicinity could number as much as 50 million members.

The image shows the paths that the two asteroids will take as they swing past Earth. When they are nearest, they should become visible to amateur astronomers with moderate-sized telescopes. 


Objects of this class, 10-meter-sized near-Earth asteroids, have asmall chance of hitting the planet, but a high chance of passing within lunar distance. This occurs once per day on average. 

“Near-Earth asteroid 2010 RX30 is estimated to be 32 to 65 feet (10 to 20 meters) in size and will pass within 0.6 lunar distances of Earth (about 154,000 miles, or 248,000 kilometers) at 2:51 am PDT (5:51 a.m. EDT) Wednesday,” according to the JPL team.

“The second object, 2010 RF12, estimated to be 20 to 46 feet (6 to 14 meters) in size, will pass within 0.2 lunar distances (about 49,088 miles or 79,000 kilometers) a few hours later at 2:12 pm PDT (5:12 pm EDT),” they add. 

Keeping an eye on NEO is extremely important, given the large number of unknown space rocks that lurk in outer space. On top of that, our solar system features two asteroid belts. 

NASA's Spitzer and WISE have already been conducting intensive NEO research for some time, but the sheer volume of work to be done is massive. 

Stephen Hawking believes that one of the major factors in the possible scarcity of intelligent life in our galaxy is the high probability of an asteroid or comet colliding with inhabited planets. We have observed, Hawking points out in Life in the Universe, the collision of a comet, Schumacher-Levi, with Jupite, which produced a series of enormous fireballs, plumes many thousands of kilometers high, hot "bubbles" of gas in the atmosphere, and large dark "scars" on the atmosphere which had lifetimes on the order of weeks. 

It is thought the collision of a rather smaller body with the Earth, about 70 million years ago, was responsible for the extinction of the dinosaurs. A few small early mammals survived, but anything as large as a human, would have almost certainly been wiped out.

Through Earth's history such collisions occur, on the average every one million year. If this figure is correct, it would mean that intelligent life on Earth has developed only because of the lucky chance that there have been no major collisions in the last 70 million years. Other planets in the galaxy, Hawking believes, on which life has developed, may not have had a long enough collision free period to evolve intelligent beings.

“The threat of the Earth being hit by an asteroid is increasingly being accepted as the single greatest natural disaster hazard faced by humanity,” according to Nick Bailey of the University of Southampton's School of Engineering Sciences team, who has developed a threat identifying program.

The team used raw data from multiple impact simulations to rank each country based on the number of times and how severely they would be affected by each impact. The software, called NEOimpactor (from NASA's "NEO" or Near Earth Object program), has been specifically developed for measuring the impact of 'small' asteroids under one kilometer in diameter.

Early results indicate that in terms of population lost, China, Indonesia, India, Japan and the United States face the greatest overall threat; while the United States, China, Sweden, Canada and Japan face the most severe economic effects due to the infrastructure destroyed.

The top ten countries most at risk are China, Indonesia, India, Japan, the United States, the Philippines, Italy, the United Kingdom, Brazil and Nigeria.

“The consequences for human populations and infrastructure as a result of an impact are enormous,” says Bailey. “Nearly one hundred years ago a remote region near the Tunguska River witnessed the largest asteroid impact event in living memory when a relatively small object (approximately 50 meters in diameter) exploded in mid-air. While it only flattened unpopulated forest, had it exploded over London it could have devastated everything within the M25. Our results highlight those countries that face the greatest risk from this most global of natural hazards and thus indicate which nations need to be involved in mitigating the threat.”

What would happen to the human species and life on Earth in general if an asteroid the size of the one that created the famous K/T Event of 65 million years ago at the end of the Mesozoic Era that resulted in the extinction of the dinosaurs impacted our planet.

As Stephen Hawking says, the general consensus is that any comet or asteroid greater than 20 kilometers in diameter that strikes the Earth will result in the complete annihilation of complex life - animals and higher plants. (The asteroid Vesta, for example, one of the destinations of the Dawn Mission, is the size of Arizona).

How many times in our galaxy alone has life finally evolved to the equivalent of our planets and animals on some far distant planet, only to be utterly destroyed by an impact? Galactic history suggests it might be a common occurrence.

Impact rates depend on how many comets and asteroids exist in a particular planetary system. In general there is one major impact every million years -a mere blink of the eye in geological time. It also depends on how often those objects are perturbed from safe orbits that parallel the Earth's orbit to new, Earth-crossing orbits that might, sooner or later, result in a catastrophic K/T or Permian-type mass extinction.

The asteroid that hit Vredefort located in the Free State Province of South Africa is one of the largest to ever impact Earth, estimated at over 10 km (6 miles) wide, although it is believed by many that the original size of the impact structure could have been 250 km in diameter, or possibly larger(though the Wilkes Land crater in Antarctica, if confirmed to have been the result of an impact event, is even larger at 500 kilometers across). The town of Vredefort is situated in the crater (image). 

Dating back 2,023 million years, it is the oldest astrobleme found on earth so far, with a radius of 190km, it is also the most deeply eroded. Vredefort Dome Vredefort bears witness to the world’s greatest known single energy release event, which caused devastating global change, including, according to many scientists, major evolutionary changes. 

What has kept the Earth "safe" at least the past 65 million years, other than blind luck is the massive gravitational field of Jupiter, our cosmic guardian, with its stable circular orbit far from the sun, which assures a low number of impacts resulting in mass extinctions by sweeping up and scatters away most of the dangerous Earth-orbit-crossing comets and asteroids.

Casey Kazan via JPL

Source: http://www.rationalvedanta.net/node/131

Comments

If a asteroid or comet the size of the one that took out the dinosaurs hit today, it definitely would not take out the human race. The dinosaurs did not have submarines, mines, and did not do cave exploring in their spare time. Furthermore they did not store vast amounts of food as we do, and they did not have radios that could be used to find surviving mates. Because of all our technology and equipment, man would survive a much larger impact than the one that drove the non-avian dinosaurs into extinction.

It is very unlikely that anything natural is going to drive humans into extinction. If we go extinct in the next few hundred years it is likely be because of something we did to ourselves.

The scary thing here is "...that two asteroids discovered on Sunday will pass..." how many days they left us to prepare if they where to hit Earth?

The scary thing here is "...that two asteroids discovered on Sunday will pass..." how many days they left us to prepare if they where to hit Earth?

I think time may be making us safer, as well. It seems to me that our solar system must have been much more cluttered earlier in its existence, but by now most of the objects that could have collided with the planet have done so. After all, although the number of asteroids is large, it is finite!

I agree with the last post, as time goes by the odds are getting better because many of the deadliest bodies have already impacted over the millennium. But we are never out of the woods, and the other benefit of time is technology. In the next few hundred years we will have better warning times and tested strategies to avoid a major impact. We'll be fine!

BTW, there is new evidence that argues the fact that he Chicxulub event may not have caused the last major extinction. The new argument points at a massive(planetary sized) explosion in our solar system, possibly caused by another collision? There is mounting evidence of many planets/moons(with new photo/telescopic technology)showing scars of this event - basically the half of the sphere facing the event and even soil samples from Mars and moon. This wave would caused some sever damage to our atmosphere.
Check out the URL I posted. (The Exploded Planet Hypothesis)


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