The history of planet Earth is a fascinating story, involving catastrophic collisions with other small planets and a veritable plethora of asteroid impacts. The prevailing theory about the formation of the moon is called the giant impact hypothesis: the theory goes that a Mars-sized object, known as Theia, crashed in to the young Earth. What was left was Earth, and its moon.A new computer model suggests, however, that the Moon may not have been the only reminder of that big collision. Jack J. Lissauera of the Space Science and Astrobiology Division, NASA Ames Research Center, and John E. Chambers of the Department of Terrestrial Magnetism, Carnegie Institution ofWashington, have suggested that moonlets called Trojans may have been left behind in the collision."The giant impact that likely led to the formation of the Moon launched a lot of material into Earth orbit, and some could well have been caught in the Langrangian points," -points in space where the gravity between two objects cancels the other out, said says study team member Lissauer.   Their theory places small moonlets, or Trojans, in Earth’s orbit, for up to 100 million years. Over time, gravitational tugs from other planets would have eventually altered Earth’s orbit, even if it was only slightly.

Thus, the Langrangian points would have altered, leaving the Trojans once again susceptible to gravity. From there, they could be anywhere by now, or destroyed entirely. "The perturbations from the other planets arevery, very tiny," said Lissauer. But they change the shape of Earth's orbit, which subsequently changes the effect that the Sun's gravity has on the moons, that "...is what ultimately destabilizes the Trojans." A separate yet similar model created by Matija Cuk, an astrophysicist at the University of British Columbia in Canada has suggested that smaller, asteroid sized objects, only a few tens of kilometers in width, could have lasted longest in those stationary positions. She believes that they could have lasted a lot longer too, up to a billion years or more. However she noted that “they would have looked more like Jupiter or Venus in the sky than a satellite. They would have resembled very bright stars.”

Copyright: TheDaily Galaxy

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Articles Topic Group: Space

Articles Catagory: Mysteries of Moon

On the morning of June 30, 1908, the sky exploded over a remote region of central Siberia. A fireball as powerful as hundreds of Hiroshima atomic blasts scorched through the upper atmosphere "as if there was a second sun," according to one eyewitness. Scientists today think a small fragment of a comet or asteroid caused the "Tunguska event," so named for the Tunguska river nearby.No one knows for certain, however, because no fragment of the meteoroid has ever been found. The explosion was so vast—flattening and incinerating over an 800 square-mile swath of trees—that generations of amateur sleuths have put forward scenarios as strange as stray black holesor UFO attacks to explain the tremendous explosion.Now, a controversial scientific study suggests that a chunk of a comet caused the 5 to 10 megaton fireball—what amounts to the largest non-nuclear explosion in modern history.

Crucially, according to the new hypothesis, most of the comet bounced off the atmosphere and back into orbit around the sun. The scientists have even identified a candidate Tunguska object—now more than 100 million miles away—that was somewhere near Earth on June 30, 1908 and will be passing close to Earth again in 2045. But just how could a comet—basically a ball of water ice and cosmic dust—create such a massive explosion and leave no trace? The answer, the scientists believe, can be found in basic chemistry rather than complicated physics or evidence yet to be found. One of the mostpeculiar leftovers from the Tunguska event is the pattern of scorched earth it left behind. No mere circular blast, Tunguska’s trail of charred trees fan out like a butterfly, with outer "wings" that spread both in a north-northeast direction and a south-southeast direction. When presented with this unusual pattern, top scientists, including Giuseppe Longo of the University of Bologna in Italy and Yuri Medvedev of the Russian Institute of Applied Astronomy, have circled around two main theories—that either two separate objects exploded in the skies over the region or one object skipped over the atmosphere, circled the earth and then re-entered over the Tunguska region on its second pass. Edward Drobyshevski, a research physicist at the Russian Academy of Sciences in St. Petersburg, thinks instead that the comet fragment packed its own explosives—in the form ofhydrogen, ......

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Articles Topic Group: History

Articles Catagory: The Unexplained

Israeli authorities say they have recovered a papyrus document which appears to be nearly 2,000 years old. The document measures 15cm by 15cm (6in by 6in), and contains 15 lines of ancient Hebrew script. It appears to be a legal instruction, transferring a widow's property to her late husband's brother.It was seized from two Palestinian men in a sting operation at a Jerusalem hotel, police said. The two could face several years in jail. The Israel Antiquities Authority (IAA) said on Wednesday that the scroll was an "exceptional archeological document, of the like but a few exist," reported Israeli newspaper Haaretz. Itsaid similar scrolls had been sold worldwide for sums as high as $5-10m (£3.3-6.6m).According to the Israel Antiquities Authority (IAA), the document is written in a style of ancient Hebrew primarily associated with the Dead Sea Scrolls.

These are scriptures and apocalyptic treatises thought to have been collected by an ascetic Jewish community which lived in the desert near the Dead Sea, and preserved by the dry climate. But it remains unclear exactly where this document was obtained, said police and archaeologists. Unusually, the first line of the document indicates a precise date, the IAA said - "Year 4 [AD] to the destruction of Israel", which could indicate either AD74, when Jerusalem's Second Temple was destroyed, or AD139, the date of a Jewish revolt violently put down by Rome. The document appears to concern the transfer of property belonging to a widowcalled Miriam.

State property The IAA's Amir Ganor cautioned that the document would have to undergo laboratory analysis to authenticate it. But he expressed excitement about the discovery, suggesting that the "very important" document could "shed light on how the people of the period managed their affairs and supplement our knowledge about their way of life". The two suspects were reportedly apprehended while trying to sell the document, by police and Israeli intelligence officers who had planned the operation for weeks. According to Israeli antiquities law all archaeological artefacts are state property. The arrested men could be charged with illegally possessing and trafficking the artefacts, and could face years in jail if convicted.

Copyright: BBCNews

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Articles Topic Group: Ancients...

Articles Catagory: Archeology

A military garrison of mud-brick and seashells unearthed in Egypt's Sinai desert may be key to finding a web of pharaonic-era defenses at the northeast gateway to ancient Egypt, archaeologists said on Thursday.Archaeologists who discovered the 3,500-year-old garrison, where up to 50,000 soldiers could be posted in times of heightened tensions, say they hope inscriptions at Luxor's Karnak temple may serve as a guide to finding other outposts. But knowing the location of the garrison at the ancient city of Tharu, in aformerly fertile area of Egypt where a branch of the Nile river once met the Mediterranean Sea, is key to understanding where to start looking."As we understand from the inscription at Karnak temple, the city of Tharu had two fortifications with the Nile in the middle," said Mohamad Abdul Maqsoud, who heads archaeological exploration in Egypt's Nile Delta and Sinai regions. In their 3,000-year history, Egypt's Pharaohs often ventured across Sinai to fight Hittites and other civilizations in the area now covered by Israel, the occupied Palestinian territories, Lebanon, Jordan, Syria and Iraq. "This city was used to protect Egypt and as a gate to the Delta.

It was a post of control. If you wanted to cross the Nile, you asked for permission before you crossed the bridge," Abdul Maqsoudsaid. Most Egyptian fortifications at the time were made of stone, not easily available in the Sinai. So Egyptians used seashells to strengthen the mud brick used to build the garrison, with a 15 meter thick and 12 meter high wall to discourage attack.

Garrison used to expel Hyksos Abdul Maqsoud said a full exploration and excavation of possible pharaonic military installations in Sinai could take 15 years to complete, but he expected to find more outposts. The garrison, called Tell Heboua, is now some 15 km (9 miles) from the coast and the Nile branch is no longer there. The fortress was first used as a base from which to expel the occupying Hyksos, who occupied Egypt for some 120 years between 1620 and 1534 BC and whose capital, Avaris, was located nearby in the Delta, AbdulMaqsoud said......

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Articles Topic Group: Civilizations

Articles Catagory: Ancient Egypt