Science & TechnologyS


Blackbox

Flashback Small Stony Asteroids Will Explode and Not Hit Earth, Study Shows

Robert Roy Britt
Space
Wed, 16 Jul 2003 18:39 UTC
Image
© ISAS
When asteroids fall through Earth's atmosphere, a variety of things can happen. Large iron-heavy space rocks are almost sure to slam into the planet. Their stony cousins, however, can't take the pressure and are more likely to explode above the surface.

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.
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Calculator

Flashback Catastrophe Calculator: Estimate Asteroid Impact Effects Online

Robert Roy Britt
SPACE.com
Fri, 29 Dec 2006 12:00 UTC
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.
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Sun

Scientists discover two newborn stars


United Press International
Thu, 11 Jun 2009 00:17 UTC
Image
© UPI Photo/NASAThis undated NASA image taken by the Hubble Space Telescope shows spiral galaxy Messier 101
Pasedena, Calif.,-- Astronomers using the infrared capability of the U.S. space agency's Spitzer Space Telescope have found two newborn stars at the center of our galaxy.

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.
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Magnify

Thinnest superconducting metal created


United Press International
Thu, 11 Jun 2009 00:10 UTC
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.
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Star

One-fifth of us have lost sight of Milky Way

Heather Catchpole
Cosmos
Thu, 11 Jun 2009 00:00 UTC
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© Jeremy Stanley/WikimediaComparison 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)
Sydney -- Light pollution has caused one-fifth of the world's population - mostly in mainland Europe, Britain and the U.S. - to lose their ability to see the Milky Way in the night sky.

"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."
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Magnify

Russia: Lake Baikal exploration team to focus on science, not artifacts


RIA Novosti
Wed, 10 Jun 2009 19:38 UTC
Lake Baikal
© Wikimedia CommonsLake Baikal
An expedition to explore the depths of East Siberia's Lake Baikal, resuming on June 15, is not aimed at finding artifacts, but learning more about the world's largest freshwater body, the lake preservation fund said on Wednesday.

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."
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Sun

Betelgeuse: The incredible shrinking star?

Rachel Courtland
New Scientist
Wed, 10 Jun 2009 18:34 UTC
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© A. Dupree/CFA/R. Gilliland/STScI/NASA/ESAThe 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
Pinned prominently on Orion's shoulder, the bright red star Betelgeuse hardly seems like a wallflower. But a new study suggests the giant star has been shrinking for more than a decade.

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).
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Blackbox

Broken dwarf planet may have scarred the moon


New Scientist
Wed, 10 Jun 2009 18:30 UTC
Image
© Johnson Space Center / NASASome large impact scars on the moon appear to be around 3.9 billion years old
The shattered remnants of a dwarf planet may have bombarded the inner planets in the early solar system, suggests a new analysis of craters on the moon.

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.
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Saturn

Solar system's planets could spin out of control

Stephen Battersby
New Scientist
Wed, 10 Jun 2009 18:15 UTC
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?

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Sherlock

6,000-Year-Old Tombs Found Next to Stonehenge

Hannah Devlin
Times Online
Wed, 10 Jun 2009 14:20 UTC
A prehistoric complex, including two 6,000-year-old tombs, has been discovered by archaeologists in Hampshire.

The Neolithic tombs, which until now had gone unnoticed under farmland despite being just 15 miles from Stonehenge, are some of the oldest monuments to have been found in Britain.

Archaeologists say they will hold valuable clues about how people lived at the time and what their environment was like.

The discovery is also close to Cranborne Chase, one of the most well researched prehistoric areas in Europe.
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