Showing posts with label science. Show all posts
Showing posts with label science. Show all posts

Tuesday, March 3, 2015

A shiny spot on the dwarf planet Ceres

mariyam | 8:40 AM | Be the first to comment!

Even more impressive on the gif of planetary rotation.
The latest images from Nasa’s Dawn spacecraft reveal a pair of bright spots on Ceres, a 590-mile-wide dwarf planet, with the brightest of the two reflecting at least 40% of the sunlight that falls on it.

Scientists are unsure what the bright patches are, but given that frozen water makes up at least a quarter of the bulk of Ceres, the odds are high that they are patches of primordial ice.

There are other possibilities though. The bright spots might be the work of volcanic eruptions on Ceres that blast ice out from the body’s interior. Yet another explanation could be the materials that make up the object. Some asteroids shine brightly because of their mineral constituents. Known as enstatite asteroids, they are rich in magnesium silicates, which can reflect nearly half of the light they receive.
The Reddit thread discusses this phenomenon and the concept and calculation of albedo.  Also interesting that a 590-mile wide planet "holds enough frozen water to fill all the lakes on Earth."
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Monday, March 2, 2015

U.S. Senator Jim Inhofe tosses a snowball

mariyam | 10:21 AM | | | Be the first to comment!

The travesty is detailed at ABC News:
Sen. Jim Inhofe, a devoted climate change denier, tossed a snowball at someone on the Senate floor today as he tried to debunk climate change. 

“In case we had forgotten because we keep hearing that 2014 has been the warmest year on record, I ask the chair: You know what this is? It's a snowball and that just from outside here so it's very, very cold out. Very unseasonal,” he said. 

“So, Mr. President, catch this,” Inhofe, R-Okla., said on the Senate floor, tossing the snowball to someone off-screen as he tried to suppress a smile. 

We hear the perpetual headline that 2014 has been the warmest year on record but now the script has flipped and I think it's important since we hear it over and over and over,” Inhofe, 80, said. “As we can see with the snowball out there, this is today. This is reality.” 
That degree of ignorance in a person who helps make the laws for this country is virtually incomprehensible to me.  I can't even comment without resorting to offensive expletives.

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17th century wearable technology

mariyam | 9:10 AM | | | Be the first to comment!
This is a relic of the Chinese Qing Dynasty, and is made of pure silver. Inlaid in a ring like a decoration, the size of the abacus is 1 cm × 0.5 cm. It has seven rods and on each rod there are seven beads. With a diameter of less than 1mm, the little beads are not made of filamentary silver, because they have no seams even when being examined under a microscope. More surprisingly, the beads can be moved easily and smoothly along the silver rods. For operating this tiny abacus, fingertips are too big. It seems that the beads can only be moved by small tools such as pins. However, this is no problem for this abacus’s primary user—the ancient Chinese lady, for she only needs to pick one from her many hairpins.
More on the history of the abacus and examples of unusual ones at China Culture.
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Friday, February 20, 2015

Limpet teeth - nature's strongest natural material

mariyam | 7:41 AM | Be the first to comment!
"Spider silk is famous for its amazing toughness, and until recently a tensile strength of 1.3 gigapascals (GPa) was enough to earn it the title of strongest natural material. However, researchers report online today in the Journal of the Royal Society Interface that the record books need to be updated to properly recognize the incredible strength of the limpet teeth. Marine snails known as limpets (Patella vulgata) spend most of their lives scraping a set of small teeth along rocks in shallow ocean waters, looking for food. The constant grinding would be enough to quickly reduce most natural materials to nubs, but the limpets’ teeth boast a tensile strength of between 3 and 6.5 GPa..."
Microphotograph via the Washington Post, which offers these observations:
The teeth also bested several man-made materials, including Kevlar, a synthetic fiber used to make bulletproof vests and puncture-proof tires. The amount of weight it can withstand, Barber told the BBC, can be compared to a strand of spaghetti used to hold up more than 3,300 pounds, the weight of an adult female hippopotamus.

Their secret is in the size of their fibers, which are 1/100th the diameter of a human hair. The ultra-thin filaments avoid the holes and defects that plague larger strands — including man-made carbon fibers — meaning any structure they compose is also flawless, regardless of how big it gets.
The original publication is here.
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Sunday, February 15, 2015

The craters of Siberia - updated

mariyam | 8:50 AM | | Be the first to comment!

In July 2014, news reports appeared of a giant crater appearing in the Siberian tundra.  Salon offered a summary of possible etiologies:
A 250-foot crater of unknown depth mysteriously appeared in Siberia’s Yamal peninsula, the Siberian Times reports, and scientists today are headed over to investigate. Researchers have already ruled out a meteorite as a potential cause. Same goes, presumably, for UFOs, as some suggested. A more likely explanation, according to Anna Kurchatova, with the Sub-Arctic Scientific Research Centre, could have to do with the thawing of Siberia’s permafrost, a consequence of global warming. The rapid release of gas previously trapped in the ice, she said, could have combined with sand beneath the surface to form an underground explosion...

University of New South Wales polar scientist Chris Fogwill agrees that global warming is the likely cause. In his opinion, provided by the Sydney Morning Herald, he explained that what we’re looking at might be a collapsed “pingo,” a natural geological phenomenon associated with the melting permafrost.
As additional craters developed (or were discovered), the Washington post provided a map of their locations [top].  Since both of those articles cited The Siberian Times, I headed there for followup reports.

The first comprehensive report from The Siberian Times included several dozen ground-level and aerial photos and a video -


 - which, if not explanatory at least offered a perspective on the size of this crater.

In November, Russian scientists rappelled down into the crater.
Leader of the new mission, Vladimir Pushkarev, director of the Russian Centre of Arctic Exploration, told The Siberian Times: 'We managed to go down into the funnel, all was successful. We used climbing equipment, and it is easier to do this in winter, than in summer, with the ground now hard.

'We took all the probes we planned, and made measurements. Now scientists need time to process all the data and only then can they draw conclusions.'

The funnel of the crater is about 16.5 metres deep, not including an earthen rampart on the surface, formed in the blowout, of several metres in height.
Photos and a video at the link.
The main element - and this is our working theory to explain the Yamal crater - was a release of gas hydrates. It turned out that there are gas hydrates both in the deep layer which on peninsula is several hundred metres down, and on the layer close to the surface', said scientist Vladimir Potapov before the latest expedition. 'There might be another factor, or factors, that could have provoked the air clap. Each of the factors added up and gas exploded, leading to appearance of the crater.'

He stressed: 'The crater is located on the intersection of two tectonic faults. Yamal peninsula is seismically quiet, yet the area of the crater we looked into has quite an active tectonic life. That means that the temperature there was higher than usual.'
They drew comparisons to the Bermuda Triangle:
The name Yamal means 'the end of the world', which ironically is also a description applied to the Bermuda Triangle for those lost on boats and planes. The areas stretches from the British Overseas Territory in the North Atlantic Ocean to the Florida coast, to Puerto Rico.

Professor Yeltsov said: 'There is a version that the Bermuda Triangle is a consequence of gas hydrates reactions. They start to actively decompose with methane ice turning into gas. It happens in an avalanche-like way, like a nuclear reaction, producing huge amounts of gas. That makes ocean to heat up and ships sink in its waters mixed with a huge proportion of gas.
And these notes from a December article:
About a third of the crater is filled with water because of its melting walls and rain, and it is thought that within three years it will be almost full. Initially it was thought that by 2024 it will be difficult to see the 40 metres wide and 50 metres deep crater at all as it will be completely submerged by a lake.

But Dr Leibman told the Siberian Times that the crater may already be under water from the melting ice by next year. She said: 'Judging by the pace, by the end of next summer it may turn into a lake.

'I once heard a theory that deep Yamal lakes were mostly the result of emissions of gas. Then I just laughed at it. Now I take back my laughter: I think that a lot of deep lakes on Yamal were formed in this way.'
There is still disagreement among the Russian scientists as to whether the heat necessary to intiate this process came from above, via global warming, or from below because of tectonic activity.

Addenda March 2015:

Dozens of new craters have been reported.  These may be previously-existing craters that have been discovered, rather than newly-created ones.  Story also covered by the Washington Post.
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Friday, January 30, 2015

How the American public views science

mariyam | 4:41 PM | Be the first to comment!

As reported in the StarTribune:
The American public and U.S. scientists are light-years apart on science issues. And 98 percent of surveyed scientists say it's a problem that we don't know what they're talking about...

In eight of 13 science-oriented issues, there was a 20-percentage-point or higher gap separating the opinions of the public and members of the American Association for the Advancement of Science, according to survey work by the Pew Research Center. The gaps didn't correlate to any liberal-conservative split; the scientists at times take more traditionally conservative views and at times more liberal.

"These are big and notable gaps," said Lee Rainie, director of Pew's internet, science and technology research. He said they are "pretty powerful indicators of the public and the scientific community seeing the world differently."

In the most dramatic split, 88 percent of the scientists surveyed said it is safe to eat genetically modified foods, while only 37 percent of the public say it is safe and 57 percent say it is unsafe. And 68 percent of scientists said it is safe to eat foods grown with pesticides, compared with only 28 percent of the general public.

Ninety-eight percent of scientists say humans evolved over time, compared with 65 percent of the public. The gap wasn't quite as large for vaccines, with 86 percent of the scientists favoring mandatory childhood shots while 68 percent of the public did.
More discussion at the link. 

For a detailed analysis (and lots of charts), go to the Pew Research Center.
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Wednesday, January 28, 2015

Trees dead for 500 years - but not decayed

mariyam | 9:29 AM | | | Be the first to comment!

“We were gathering samples of dead trees to reconstruct summer temperatures in western Norway, when our dendrochronological dating showed the wood to be much older than expected”, says Terje Thun, an associate professor at the Norwegian University of Science and Technology’s (NTNU) Museum of Natural History and Archaeology...

Thun says that when a pine tree dies, it secretes a great deal of resin, which deters the microorganisms needed for decomposition. “Nevertheless, preventing the natural breakdown of the wood for centuries is quite a feat”, he says...
Resin was one of the ingredients used in Ancient Egypt for mummification, so its conservation abilities have been known for millennia. However, that trees could “self-mummify” in such a humid climate for centuries was new to the NTNU scientists.
“Many of the trunks we dated turned out to have seeded in the early 1200s, and had lived for more than 100 years at the time of the Black Death around 1350”, Thun says. “That means that the dead wood has ‘survived’ in nature for more than 800 years without breaking down.”
More at the link. The tree in the photo grew began growing in 1334, and died in 1513!  
Reposted from 2009.  Photo credit: Terje Thun, NTNU.
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Saturday, January 24, 2015

The complicated tail of Comet Lovejoy

mariyam | 8:51 AM | Be the first to comment!

From APOD:
Comet C/2014 Q2 (Lovejoy), which is currently at naked-eye brightness and near its brightest, has been showing an exquisitely detailed ion tail. As the name implies, the ion tail is made of ionized gas -- gas energized by ultraviolet light from the Sun and pushed outward by the solar wind. The solar wind is quite structured and sculpted by the Sun's complex and ever changing magnetic field. The effect of the variable solar wind combined with different gas jets venting from the comet's nucleus accounts for the tail's complex structure...

The blue color of the ion tail is dominated by recombining carbon monoxide molecules, while the green color of the coma surrounding the head of the comet is created mostly by a slight amount of recombining diatomic carbon molecules...

Comet Lovejoy made its closest pass to the Earth two weeks ago and will be at its closest to the Sun in about ten days. After that, the comet will fade as it heads back into the outer Solar System, to return only in about 8,000 years.
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