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On February 4, 2011, the asteroid 2011 CQ1 narrowly missed the earth, coming within 3,400 miles (5471 km). Five days later, a larger asteroid called 2011 GA7 passed within 65,000 miles—both astronomical near misses. On February 15, 2011, a silver streak appeared in the sky over Pennsylvania and was seen in New York, New Jersey, Connecticut and Maryland. Some astronomers are concerned that an astoroid named Apophis will strike the earth in 2036. Will this be earth's doom?
There are 347 objects listed on the National Aeronautics and Space Administration's (NASA) Near Earth Object Program list. A system called Sentry, an automated collision-monitoring system, continually scans an asteroid catalog for possible future impacts with the earth. At present, only two are listed with a Torino Impact Hazard Scale of 1, meaning "it merits careful monitoring." One is 2011 AG5 which is 140 meters in diameter, and the other is 2007 VK184 which is 130 meters in diameter. These are both large enough to be of concern.
Scientists say the meteor over Pennsylvania was probably the size of a car. It landed in the Atlantic Ocean. Most asteroids 50 meters or less in size are not thought to pose a significant threat to the earth. Small asteroids like 2011 CQ1, mentioned above, at only 4 feet in diameter, would likely break apart and incinerate before hitting the earth. But a collision with a larger asteroid is of enough concern that a significant effort is being made to detect and track them.
The asteroid named 99942 Apophis (2004 MN4) with an estimated diameter of 900 feet (270 meters) is large enough to cause very significant damage if it were to strike the earth. While NASA shows it as having six potential impacts between 2036 and 2103, its Torino scale of 0 means they do not calculate it will impact the earth. However, it is in the news since Russian scientists estimate it will collide with earth on April 13, 2036.
There are several phenomena that make the tracking of an asteroid less than certain. One is the effect of what is called a "gravitational keyhole," which could alter an asteroid's orbital path. Another is the gentle increase in speed from thermal radiation. And another is the unpredictable alteration in course due to colliding with other asteroids.
An even larger asteroid, 1999 RQ36, is 1,837 feet (560 meters) in diameter. Its impact could destroy the earth. It is estimated that it could hit the earth in 2182 when the asteroid's orbit comes closest to the earth. Of course, the hope is that efforts could be mounted in time to destroy or deflect the asteroid away from the earth.
Some effort has also been made to consider biblical predictions of "Armageddon" to include an impact event. The Bible mentions stars of heaven falling on the earth like a fig tree dropping figs due to a strong wind (Revelation 6:13). Called by futurists the "Wormwood Star Prophecy," they interpret the account in Revelation 8:10–11 as a comet, or asteroid, impacting the earth and chemically changing the atmosphere due to "heat shock," which would result in nitric acid rain. They believe this rain would produce "bitterness" in one-third of the potable waters of the earth.
Astronomers do consider the threat of cosmic bombardment to be real. They recognize that there are thousands of undiscovered "near earth objects," and that new comets enter our solar system regularly. Early detection is necessary so there will be time to mount measures to avert an impact with the earth, either by destroying, or deflecting the asteroid away from the earth.
For more perspective on this subject, search this website for vital articles and booklets, such as "Asteroids: Media Hype or Menacing Danger?"; "The End of the Universe?" and Armageddon and Beyond.
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