Meteorite fragments of the first asteroid ever spotted in space before it slammed into Earth's atmosphere last year were recovered by scientists from the deserts of Sudan.
These precious pieces of space rock, described in a study detailed in the March 26 issue of the journal Nature, could be an important key to classifying meteorites and asteroids and determining exactly how they formed.
The asteroid was detected by the automated Catalina Sky Survey telescope at Mount Lemmon , Ariz., on Oct. 6, 2008. Just 19 hours after it was spotted, it collided with Earth's atmosphere and exploded 23 miles (37 kilometers) above the Nubian Desert of northern Sudan.
Because it exploded so high over Earth's surface, no chunks of it were expected to have made it to the ground. Witnesses in Sudan described seeing a fireball, which ended abruptly.
But Peter Jenniskens, a meteor astronomer with the SETI Institute's Carl Sagan Center, thought it would be possible to find some fragments of the bolide. Along with Muawia Shaddad of the University of Khartoum and students and staff, Jenniskens followed the asteroid's approach trajectory and found 47 meteorites strewn across an 18-mile (29-km) stretch of the Nubian Desert.
Science & Technology
© ISAS
Either outcome can be dismal. But the consequences vary.
So scientists who study the potential threat of asteroids would like to know more about which types and sizes of asteroids break apart and which hold together. A new computer model helps to quantify whether an asteroid composed mostly of stone will survive to create a crater or not.
A stony space rock must be about the size of two football fields, or 720 feet (220 meters) in diameter, to endure the thickening atmosphere and slam into the planet, according to the study, led by Philip Bland of the Department of Earth Science and Engineering at Imperial College London.
"Stones of that size are just at the border where they're going to reach the surface -- a bit lower density and strength and it'll be a low-level air burst, a bit higher and it'll hit as a load of fragments and you'll get a crater," said Bland, who is also a Royal Society Research Fellow.
The history of Earth's encounters with asteroids remains largely mysterious to scientists. They can't even agree whether a huge space rock that hit Mexico's Yucatan Penninsula 65 million years ago killed off the dinosaurs or not.
Nor can astronomers say when the next catastrophic impact will occur. They only know that it will happen, sooner or later.
However, now anyone with a passing interest in the fate of the planet can remove some of the mystery regarding the effects of the next collision. A new University of Arizona web page allows visitors to plug in a hypothetical space rock's size, the visitor's distance from the impact site, and other parameters to generate an outline of devastation.
But be warned: Removing the mystery invites a bit of terror over the hypothetical slams, bangs, fireballs, falling skies and rushing winds generated by a giant impact.
Nor can astronomers say when the next catastrophic impact will occur. They only know that it will happen, sooner or later.
However, now anyone with a passing interest in the fate of the planet can remove some of the mystery regarding the effects of the next collision. A new University of Arizona web page allows visitors to plug in a hypothetical space rock's size, the visitor's distance from the impact site, and other parameters to generate an outline of devastation.
But be warned: Removing the mystery invites a bit of terror over the hypothetical slams, bangs, fireballs, falling skies and rushing winds generated by a giant impact.
© UPI Photo/NASA
This undated NASA image taken by the Hubble Space Telescope shows spiral galaxy Messier 101
This undated NASA image taken by the Hubble Space Telescope shows spiral galaxy Messier 101
The heart of the Milky Way spiral galaxy is cluttered with stars, dust and gas, and at its center, a supermassive black hole, National Aeronautics and Space Administration scientists said. Conditions there are harsh, but astronomers have known stars can form in such chaotic space, however, until now nobody had been able to definitively locate any such baby stars.
Austin Texas, -- University of Texas at Austin physicists have created a superconducting lead sheet only two atoms thick, the thinnest such metal layer ever created.
Professor Ken Shih and colleagues said the achievement lays the groundwork for future superconductor technologies.
Professor Ken Shih and colleagues said the achievement lays the groundwork for future superconductor technologies.
© Jeremy Stanley/Wikimedia
Comparison showing the effects of light pollution on viewing the sky at night. The southern sky, featuring Sagittarius and Scorpius. Top image shows the sky from Leamington, Utah (population 217). Bottom image shows Orem, Utah (metropolitan area with a population of around 400,000)
Comparison showing the effects of light pollution on viewing the sky at night. The southern sky, featuring Sagittarius and Scorpius. Top image shows the sky from Leamington, Utah (population 217). Bottom image shows Orem, Utah (metropolitan area with a population of around 400,000)
"The arc of the Milky Way seen from a truly dark location is part of our planet's natural heritage," said Connie Walker, and astronomer from the U.S. National Optical Astronomy Observatory in Tucson, Arizona.
Yet "more than one fifth of the world population, two thirds of the U.S. population and one half of the European Union population have already lost naked eye visibility of the Milky Way."
© Wikimedia Commons
Lake Baikal
Lake Baikal
Two mini-subs conducted 52 dives last summer, also searching for gold taken by the White Army's Admiral Alexander Kolchak before he fled from the Bolsheviks across the lake in the winter of 1919-1920. No artifacts except for boxes of ammunition dating back to the 1920s have been discovered.
"The expedition does not aim to find the maximum depth of the lake or search for archaeological artifacts," the fund said in a statement. "But if new data on the issues is discovered during the planned dives, it will undoubtedly be made public."
© A. Dupree/CFA/R. Gilliland/STScI/NASA/ESA
The red supergiant Betelgeuse would extend to Jupiter if it were put in the sun's place in the solar system. A new study suggests it has shrunk by more than 15 per cent since 1993
The red supergiant Betelgeuse would extend to Jupiter if it were put in the sun's place in the solar system. A new study suggests it has shrunk by more than 15 per cent since 1993
Betelgeuse is nearing the end of its life as a red supergiant. The bright, bloated star is 15 to 20 times more massive than the sun. If it were placed at the centre of the solar system, the star would extend out to the orbit of Jupiter.
But the star's reach seems to be waning. New observations indicate the giant star has shrunk by more than 15 per cent since 1993. This could be a sign of a long-term oscillation in its size or the star's first death knells. Or it may just be an artefact of the star's bumpy surface, which may appear to change in size as the star rotates.
Betelgeuse is enshrouded by vast clouds of gas and dust, so measuring its size is difficult. To cut through this cocoon, Charles Townes of the University of California, Berkeley, and colleagues used a set of telescopes that are sensitive to a particular wavelength of the star's infrared light.
The team used these instruments to measure the size of Betelgeuse's disc on the sky. Over a span of 15 years, the star's diameter seems to have declined from 11.2 to 9.6 AU (1 AU, or astronomical unit, is the distance from the Earth to the sun).
© Johnson Space Center / NASA
Some large impact scars on the moon appear to be around 3.9 billion years old
Some large impact scars on the moon appear to be around 3.9 billion years old
Several large impact scars on the moon appear to be around 3.9 billion years old, suggesting that the Earth and other objects of the inner solar system were heavily pounded at that time. Most astronomers believe that the bombardment was caused by shifts in the orbits of the giant planets, which destabilised the asteroid belt, hurling giant rocks our way.
But the distribution of small and large lunar craters does not match the numbers of small and large objects in the asteroid belt today, says a team led by Matija Cuk of Harvard University, who spoke at a meeting of the American Geophysical Union in Toronto, Canada, last week.
The solar system's clockwork motion is by no means guaranteed: one day the Earth could collide with Venus or tear Mars apart in a close encounter, a new simulation has shown.
We know that the apparently reliable orbits of the planets are unstable in the long run, because their weak gravitational effects on one another can add up in unpredictable ways. Technically, the system is chaotic. Could this very mild chaos lead to disaster?
We know that the apparently reliable orbits of the planets are unstable in the long run, because their weak gravitational effects on one another can add up in unpredictable ways. Technically, the system is chaotic. Could this very mild chaos lead to disaster?
