Science & Technology
Astronomers have long stated that a large number of meteoroids frequently impact the Earth. Such incidents are rarely reported despite the enormous amount of energy released. However, newly-declassified documents show that secret military surveillance systems have been detecting such events.
Meteorites provide information about the formation of the Solar System. They are pieces of very old material that have fallen from space to the Earth. Most result from asteroid collisions in the Asteroid Belt between Mars and Jupiter, but over a dozen from the Moon and another 12 from Mars have also been identified. The three main types of meteorite are stone, iron, and stony-iron. Stony-iron meteorites are the rarest and are often quite beautiful. Antarctica is the best place to find meteorites because there the ice and aridity preserve them, sometimes for as long as a million years.
Each year approximately 40,000 tonnes of extraterrestrial material, most of it dust, bombards the earth. But where does it come from, and why does it land here?
Visitors from space arrive on the Earth with amazing frequency, not as alien monsters or little green people in flying saucers, but as meteorites, extraterrestrial material ranging from the tiniest of dust grains to enormous impact crater-forming bodies. Meteorites were formed at the birth of the Solar System, about 4,560 million years ago. We have no material on Earth this old, so it is only by studying meteorites that we can learn about the processes that shaped our Solar System and our planet.
Each year approximately 40,000 tonnes of extraterrestrial material, most of it dust, bombards the earth. But where does it come from, and why does it land here?
Visitors from space arrive on the Earth with amazing frequency, not as alien monsters or little green people in flying saucers, but as meteorites, extraterrestrial material ranging from the tiniest of dust grains to enormous impact crater-forming bodies. Meteorites were formed at the birth of the Solar System, about 4,560 million years ago. We have no material on Earth this old, so it is only by studying meteorites that we can learn about the processes that shaped our Solar System and our planet.
Secret data from military satellites in orbit thousands of miles above Earth show that the planet is continually bombarded by big meteoroids that explode in blasts the size of atomic detonations. The data, from spacecraft meant to watch for rocket firings and nuclear explosions, were declassified recently by the Defense Department and are to appear later this year in a book.
From 1975 to 1992, the satellites detected 136 explosions high in the atmosphere, an average of eight a year. The blasts are calculated to have intensities roughly equal to 500 to 15,000 tons of high explosive, or the power of small atomic bombs. Experts who have analyzed the data are publishing it in the book, Hazards Due to Comets and Asteroids, say that the detection rate is probably low and that the actual bombardment rate might be 10 times higher, with 80 or so blasts occurring each year.
From 1975 to 1992, the satellites detected 136 explosions high in the atmosphere, an average of eight a year. The blasts are calculated to have intensities roughly equal to 500 to 15,000 tons of high explosive, or the power of small atomic bombs. Experts who have analyzed the data are publishing it in the book, Hazards Due to Comets and Asteroids, say that the detection rate is probably low and that the actual bombardment rate might be 10 times higher, with 80 or so blasts occurring each year.
An international project to make the world's most productive ground-based telescope 10 times more capable has reached its halfway mark and is on schedule to provide astronomers with an extremely powerful new tool for exploring the Universe. The National Science Foundation's Very Large Array (VLA) radio telescope now has half of its giant, 230-ton dish antennas converted to use new, state-of-the-art digital electronics to replace analog equipment that has served since the facility's construction during the 1970s.
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| ©NRAO/AUI/NSF |
| VLA antennas getting modern electronics to meet new scientific challenges. |
Very young brains process memories of fear differently than more mature ones, new research indicates. The work significantly advances scientific understanding of when and how fear is stored and unlearned, and introduces new thinking on the implications of fear experience early in life.
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| ©iStockphoto |
| Very young brains process memories of fear differently than more mature ones, new research indicates. The work significantly advances scientific understanding of when and how fear is stored and unlearned, and introduces new thinking on the implications of fear experience early in life. |
A next-generation atomic clock that tops previous records for accuracy in clocks based on neutral atoms has been demonstrated by physicists at JILA, a joint institute of the Commerce Department's National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder. The new clock, based on thousands of strontium atoms trapped in grids of laser light, surpasses the accuracy of the current U.S. time standard based on a "fountain" of cesium atoms.
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| ©Greg Kuebler/JILA |
| JILA's strontium atomic clock is now the world's most accurate clock based on neutral atoms. |
At the forefront of the brain or buried near its stem is the glue of civility. It is here, science believes, that nature first raises its hand in discipline.
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| ©Signs of the Times |
Certain Russian politicians and businessmen could be elected members of the Russian Academy of Sciences (RAS), a leading Russian business daily said Monday.
Kommersant said that Audit Chamber head Sergei Stepashin, leading banker Garegin Tosunyan, Khabarovsk Region governor Viktor Ishayev and senator Gleb Fetisov would be likely to seek election to the RAS.
"I believe if a person occupies a public position and is a good academic, he should not be banned from becoming an RAS member," academician Alexander Chubaryan said.
Kommersant said that Audit Chamber head Sergei Stepashin, leading banker Garegin Tosunyan, Khabarovsk Region governor Viktor Ishayev and senator Gleb Fetisov would be likely to seek election to the RAS.
"I believe if a person occupies a public position and is a good academic, he should not be banned from becoming an RAS member," academician Alexander Chubaryan said.
If you could hold a giant magnifying glass in space and focus all the sunlight shining toward Earth onto one grain of sand, that concentrated ray would approach the intensity of a new laser beam made in a University of Michigan laboratory.
Have you ever arrived somewhere and wondered how you got there? Scientists at the University of Leeds believe they may have found the answer, with research that shows that humans flock like sheep and birds, subconsciously following a minority of individuals.
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