Science blog
Orbital mechanics affect methane levels
Antarctic lake keeps its secrets for now
How snakes lost their legs
Researchers ponder cancer origins
Forming social networks a no-brainer
'Niceness' partly genetic, say scientists
Omega-3 may keep blindness at bay
Coral shines light on rainfall records
Old bone proves Lucy was no swinger
Scientists unlock cosmic ice riddle
Study links pesticides to Parkinson's
Digital world growing faster every year
Energy drinks put kids at risk: report
Robotics speed up cancer drug development
Zinc cuts short the common cold
Counting kicks in at 18 months
NASA spacecraft unravels comet mystery
Astronomers dig up cannibalised galaxy
Study links extreme weather to climate change
Turkey quake gives warning clues
US scientists build first 'antilaser'
Website meltdown leaves scientists fuming
Earth 'unrecognisable' by 2050: experts
Canola fungus genome unravelled
Читать: | Читаем здесь: | Тут: |
Tiny grains record solar system's infancy
Tiny grains of dust are providing the earliest glimpse of the primordial solar system before Earth was born.

The particles, called calcium-aluminium rich inclusions or CAIs, are found inside meteorites. Scientists believe these 4.57 billion-year-old particles acted as tiny travel diaries, tracing their journey through the early solar nebula.

The discovery by a team of researchers including Dr Justin Simon, an astromaterials specialist with NASA's Johnson Space Center in Houston, is shedding new light on the processes that created the protoplanetary disk of matter around the early Sun.

Simon chose a pea-size CAI from the Allende meteorite, the largest carbonaceous chondrite ever found on Earth.

Estimated to have been the size of a car, it broke up as it fell through the atmosphere in 1969, showering the ground in Chihuahua, Mexico, with hundreds of pieces.

After cross-sectioning, they found distinct mineral layers had formed along the rim of the core, like layers of an onion.
Oxygen isotopes were the key

Simon used an ion microprobe called NanoSIMS (secondary ion mass spectrometer) to sample oxygen isotopes in micrometre-scale layers inside the CAI with resolutions of just 2-microns.

Because the relative abundance of oxygen isotopes varied in the protoplanetary disk, Simon and colleagues were able to pinpoint where a mineral formed.

Reporting in the journal Science, the researchers found the CAIs probably first condensed out of molecular gas into a solid, in an oxygen-16 rich environment near the Sun.

"It then encountered an oxygen poor environment, losing oxygen-16, possibly by being thrown out of the plane of the solar system, before falling into a planet-forming environment around where the asteroid belt is now," says Simon.

"I was surprised to find that it eventually recirculated back to the inner solar system."

But the findings, according to Simon, are consistent with some theories about the early protoplanetary nebula.
The X-wind theory

According to one theory the Sun's magnetic fields churned the gas and dust inside the early protoplanetary disk, tossing out grains formed near the Sun .

Once expelled, the grains fell like rain into the outer solar system and eventually incorporated into asteroids and planets.

According to Simon, the work follows on from decades of cosmochemistry and astrophysics research.

"Genesis defined the Sun's composition in terms of oxygen isotopes. That's where the oxygen-16 comes from," he says. "Stardust collected comet dust finding what looked like CAI's and providing the first evidence for a transfer of material from the inner to the outer solar system."

Brain efficiency comes from parents
Backward bending light key to stealth
Signs of 'alien life' found in meteorites
Accurate blood test for Down's
Disaster volunteers at risk: study
Elephants smart as chimps, dolphins
Gadgets ruining people's sleep
Why skin doesn't dissolve in the bath
Astronomers find old heads in a young crowd
Paper leads to perfect beer head
Researchers locate brain's loudness map
Jamming may leave GPS in the wilderness
Pain washes guilt away
Quake could alter Tokyo risk: experts
Japan meltdown not like Chernobyl: expert
Dreamtime astronomers understood meteors
CERN restarts search for cosmic origins
Nuclear Contamination: What to Do
Bet-hedging 'key to natural selection'
Humans age same as other primates
US overdue, under-prepared for huge quake
Sperm's egg-seeking secrets revealed
Lasers to nudge space junk out harm's way
Researchers uncover gastro's sugary secret
Kepler probes inside swollen red giant
Randomness could 'improve democracy'
Moonageddon: Apocalypse not
Museum unveils Columbian mammoth
Ink-jet inspire scientists to make skin
Seaweed offers clues against malaria
Christchurch quakes may be connected
Solar storms pose risk to technology
Study finds fences thwart cane toad
Mobile phone alters brain activity
Sticky dots approved for clinical trial
Humans stink worse than other animals
Putting the bounce in carbon balls
Sulphur secrets uncovered
Cool laser makes atoms march in time
Hot flashes may be a sign of good heart
Scientists see the birth of a new planet
X-ray expectations change search methods
Eucalypt-harming fungus here to stay
Life elements came from outer space
Cricket wimps use perfume to find mates
Orphan planets could support life
Speech lights up visual cortex in blind
How the Sun loses its spots
Cancer resistance mechanism found
Fungus turns Amazonian ants into zombies
Tiny grains record solar system's infancy
Antarctic ice forming beneath glaciers
Visit Statistics