Science & Technology
Jules Verne is about to become a fireball. On Sept. 29th, with NASA airplanes looking on, the 22-ton European spacecraft will plunge into Earth's atmosphere over the south Pacific Ocean. Jules Verne recently spent five months docked to the space station where it delivered supplies, used its engines help the station avoid a piece of space junk, and served as an impromptu bedroom for the ISS crew. Mission accomplished, the doomed spacecraft is now making its final orbits around Earth. If you'd like to see it, check the Simple Satellite Tracker for viewing times.
Astronomers have identified the least luminous galaxy known, but it's surprisingly massive. The reason: It is loaded with invisible matter.
Dark matter is mysterious, unseen stuff that permeates the universe. Astronomers know it's there because of the gravity it creates. Without invoking dark matter, theories can't explain how galaxies stay together.
The galaxy, called Segue 1, is one of about two dozen small satellite galaxies orbiting our own Milky Way galaxy. A separate study last month, reported in the journal Science, found that all the known satellite galaxies are loaded with dark matter.
But among them, Segue 1 is special. It is a billion times less bright than the Milky Way. Yet it's nearly a thousand times more massive than its star light would suggest.
Dark matter is mysterious, unseen stuff that permeates the universe. Astronomers know it's there because of the gravity it creates. Without invoking dark matter, theories can't explain how galaxies stay together.
The galaxy, called Segue 1, is one of about two dozen small satellite galaxies orbiting our own Milky Way galaxy. A separate study last month, reported in the journal Science, found that all the known satellite galaxies are loaded with dark matter.
But among them, Segue 1 is special. It is a billion times less bright than the Milky Way. Yet it's nearly a thousand times more massive than its star light would suggest.
The skeleton of a man discovered by archaeologists in a shallow grave on the site of the University of York's campus expansion could be that of one of Britain's earliest victims of tuberculosis.
Radiocarbon dating suggests that the man died in the fourth century. He was interred in a shallow scoop in a flexed position, on his left side.
The man, aged 26 - 35 years, suffered from iron deficiency anaemia during childhood and at 162 centimetres (5ft 4in), was a shorter height than average for Roman males.
The first known case of TB in Britain is from the Iron Age (300 BC) but cases in the Roman period are fairly rare, and largely confined to the southern half of England. TB is most frequent from the 12th century AD in England when people were living in urban environments. So the skeleton may provide crucial evidence for the origin and development of the disease in this country.
The remains were discovered during archaeological investigations on the site of the University's £500 million expansion at Heslington East. Archaeologists unearthed the skeleton close to the perimeter of the remains of a late - Roman masonry building discovered on the site, close to the route of an old Roman road between York and Barton - on - Humber.
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| ©University of York |
| A recently discovered skeleton could be that of one of Britain's earliest victims of tuberculosis. The man suffered from iron deficiency anaemia during childhood and was a shorter height than average for Roman males. |
Radiocarbon dating suggests that the man died in the fourth century. He was interred in a shallow scoop in a flexed position, on his left side.
The man, aged 26 - 35 years, suffered from iron deficiency anaemia during childhood and at 162 centimetres (5ft 4in), was a shorter height than average for Roman males.
The first known case of TB in Britain is from the Iron Age (300 BC) but cases in the Roman period are fairly rare, and largely confined to the southern half of England. TB is most frequent from the 12th century AD in England when people were living in urban environments. So the skeleton may provide crucial evidence for the origin and development of the disease in this country.
The remains were discovered during archaeological investigations on the site of the University's £500 million expansion at Heslington East. Archaeologists unearthed the skeleton close to the perimeter of the remains of a late - Roman masonry building discovered on the site, close to the route of an old Roman road between York and Barton - on - Humber.
Materials deep inside Earth have unexpected atomic properties that might force earth scientists to revise their models of Earth's internal processes, a team of researchers has discovered.
The researchers recreated in the lab the materials, crushing pressures and infernal temperatures they believe exist in the lowermost mantle, nearly 2,900 kilometers (1,800 miles) below Earth's surface. They report in the journal Nature Geoscience the materials exhibit rare and unexpected atomic properties that might influence how heat is transferred within Earth's mantle, how columns of hot rock called superplumes form, and how the magnetic field and heat generated in Earth's core travel to the planet's surface.
The planetary building blocks magnesium, silicon, oxygen and iron are the most abundant minerals in the lowermost mantle. A team of scientists led by Jung-Fu Lin at The University of Texas at Austin's Jackson School of Geosciences synthesized materials from these building blocks in a diamond anvil cell, a device containing two interlocking diamond pieces that squeeze the sample like a vice. They subjected the sample to more than 1.3 million times standard atmospheric pressure. Shining a laser through the transparent diamonds, they then heated the sample to almost 3,000 degrees Celsius (5,400 degrees Fahrenheit) for several days.
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| ©University of Texas at Austin |
| Jung-Fu Lin and colleagues used a diamond anvil cell to recreate materials and conditions in Earth's lowermost mantle. |
The researchers recreated in the lab the materials, crushing pressures and infernal temperatures they believe exist in the lowermost mantle, nearly 2,900 kilometers (1,800 miles) below Earth's surface. They report in the journal Nature Geoscience the materials exhibit rare and unexpected atomic properties that might influence how heat is transferred within Earth's mantle, how columns of hot rock called superplumes form, and how the magnetic field and heat generated in Earth's core travel to the planet's surface.
The planetary building blocks magnesium, silicon, oxygen and iron are the most abundant minerals in the lowermost mantle. A team of scientists led by Jung-Fu Lin at The University of Texas at Austin's Jackson School of Geosciences synthesized materials from these building blocks in a diamond anvil cell, a device containing two interlocking diamond pieces that squeeze the sample like a vice. They subjected the sample to more than 1.3 million times standard atmospheric pressure. Shining a laser through the transparent diamonds, they then heated the sample to almost 3,000 degrees Celsius (5,400 degrees Fahrenheit) for several days.
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| ©NASA |
This is exactly why we send astronauts to risk their life to service Hubble: in a paper published last week in the Astrophysical Journal, scientists detail the discovery of a new unidentified object in the middle of nowhere. I don't know about you, but when a research paper conclusion says "We suggest that the transient may be one of a new class" I get a chill of oooh-aaahness down my spine. Especially when after a hundred days of observation, it disappeared from the sky with no explanation. Get your tinfoil hats out, because it gets even weirder.
The BBC and the National Geographic Channel are making a documentary based on the controversial theories of a Wollongong academic, who claims that meteorites hit the earth every 1000 years.
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| ©Sylvia Liber |
| Professor Ted Bryant with the US film crew at Jones Beach. |
A long-standing scientific belief holds that stars tend to hang out in the same general part of a galaxy where they originally formed. Some astrophysicists have recently questioned whether that is true, and now new simulations show that, at least in galaxies similar to our own Milky Way, stars such as the sun can migrate great distances.
What's more, if our sun has moved far from where it was formed more than 4 billion years ago, that could change the entire notion that there are parts of galaxies - so-called habitable zones - that are more conducive to supporting life than other areas are.
"Our view of the extent of the habitable zone is based in part on the idea that certain chemical elements necessary for life are available in some parts of a galaxy's disk but not others," said Rok Roškar, a doctoral student in astronomy at the University of Washington.
"If stars migrate, then that zone can't be a stationary place."
If the idea of habitable zone doesn't hold up, it would change scientists' understanding of just where, and how, life could evolve in a galaxy, he said.
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| ©Rok Roškar |
| This image is from a computer simulation showing the development and evolution of the disk of a galaxy such as the Milky Way. |
What's more, if our sun has moved far from where it was formed more than 4 billion years ago, that could change the entire notion that there are parts of galaxies - so-called habitable zones - that are more conducive to supporting life than other areas are.
"Our view of the extent of the habitable zone is based in part on the idea that certain chemical elements necessary for life are available in some parts of a galaxy's disk but not others," said Rok Roškar, a doctoral student in astronomy at the University of Washington.
"If stars migrate, then that zone can't be a stationary place."
If the idea of habitable zone doesn't hold up, it would change scientists' understanding of just where, and how, life could evolve in a galaxy, he said.
Oxygen is the most abundant element on Earth, accounting for almost half the planet's mass. Of its three stable isotopes, oxygen 16 (16O, whose nucleus contains eight neutrons) makes up 99.762 percent of oxygen on Earth, while heavier oxygen 17 (17O, with nine neutrons) accounts for just 0.038 percent, and the heaviest isotope, oxygen 18 (18O, with 10 neutrons), makes up 0.2 percent.
Yet minerals in some of the most primitive objects in the solar system, including the meteorites called carbonaceous chondrites, have quite different ratios of oxygen isotopes than on Earth; presumably the rare heavy isotopes occurred in much greater abundances in the early solar system.
"For a chemist, the question of oxygen-isotope ratios is one that could help us understand the origins of the solar system," says Musahid (Musa) Ahmed of Berkeley Lab's Chemical Sciences Division, a beamline scientist at the Chemical Dynamics beamline, 9.0.2, at the Advanced Light Source (ALS). "Why meteoritic oxygen isotope ratios are significantly different from those on Earth has mystified scientists for years."
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| ©NASA |
| The sun in ultraviolet light. When the solar system was forming, the protosun was a potent source of vacuum ultraviolet. |
Yet minerals in some of the most primitive objects in the solar system, including the meteorites called carbonaceous chondrites, have quite different ratios of oxygen isotopes than on Earth; presumably the rare heavy isotopes occurred in much greater abundances in the early solar system.
"For a chemist, the question of oxygen-isotope ratios is one that could help us understand the origins of the solar system," says Musahid (Musa) Ahmed of Berkeley Lab's Chemical Sciences Division, a beamline scientist at the Chemical Dynamics beamline, 9.0.2, at the Advanced Light Source (ALS). "Why meteoritic oxygen isotope ratios are significantly different from those on Earth has mystified scientists for years."
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| ©University of Toronto |
| Young star 1RXS J160929.1-210524 and its faint, planetary mass candidate companion. Blue, green, and red represent images taken in J, H, and Ks, with intensities scaled such that they are proportional to the photon rates inferred from the 2MASS magnitudes of the primary |
University of Toronto astronomers have unveiled what is likely the first picture of a planet around a star similar to the sun.
An international team of scientists predict that our Galaxy, the Milky Way, contains a disk of 'dark matter'. Astronomers Dr Justin Read, Professor George Lake and Oscar Agertz of the University of Zurich, and Dr Victor Debattista of the University of Central Lancashire use the results of a supercomputer simulation to deduce the presence of this disk.
They explain how it could allow physicists to directly detect and identify the nature of dark matter for the first time.
Unlike the familiar 'normal' matter that makes up stars, gas and dust, 'dark' matter is invisible but its presence can be inferred through its gravitational influence on its surroundings. Physicists believe that it makes up 22% of the mass of the Universe (compared with the 4% of normal matter and 74% comprising the mysterious 'dark energy'). But, despite its pervasive influence, no-one is sure what dark matter consists of.
Prior to this work, it was thought that dark matter forms in roughly spherical lumps called 'halos', one of which envelopes the Milky Way. But this 'standard' theory is based on supercomputer simulations that model the gravitational influence of the dark matter alone. The new work includes the gravitational influence of the stars and gas that also make up our Galaxy.
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| ©. Read and O. Agertz |
| A composite image of the dark matter disk (red contours) and the Atlas image mosaic of the Milky Way obtained as part of the Two Micron All Sky Survey (2MASS). |
They explain how it could allow physicists to directly detect and identify the nature of dark matter for the first time.
Unlike the familiar 'normal' matter that makes up stars, gas and dust, 'dark' matter is invisible but its presence can be inferred through its gravitational influence on its surroundings. Physicists believe that it makes up 22% of the mass of the Universe (compared with the 4% of normal matter and 74% comprising the mysterious 'dark energy'). But, despite its pervasive influence, no-one is sure what dark matter consists of.
Prior to this work, it was thought that dark matter forms in roughly spherical lumps called 'halos', one of which envelopes the Milky Way. But this 'standard' theory is based on supercomputer simulations that model the gravitational influence of the dark matter alone. The new work includes the gravitational influence of the stars and gas that also make up our Galaxy.
