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Everyone liked to blow soap bubbles, right? And everyone was sad but excited when these bubbles burst! Now here comes the science which describes what exactly happens ;)

How the bubble bursts

Popping bubbles create offspring, scientists find.

Not all cutting-edge physics requires a particle accelerator. Using a straw and some soap, researchers have shown how a popping bubble can produce more bubbles. The work is published in this week's issue of Nature1.

news.2010.bubble.Figure1a_d.jpg


James Bird, now a postdoc at Massachusetts Institute of Technology in Cambridge, first noticed the effect while working on another experiment for his PhD at nearby Harvard University. When a bubble on a fluid's surface popped, Bird noticed that a ring of small bubbles formed where the bubble's edge had once stood.

"We saw this effect and couldn't really explain it," he recalls. So he and his colleagues decided to investigate. They began blowing bubbles through a straw and filming them with a high-speed camera as they popped.

Previous work had suggested that a ruptured bubble might vanish or break up and fall to the surface, but Bird saw something different. Rather than exploding, the walls of the bubble actually fold back on themselves. As they do so, they trap a small doughnut-shaped ring of air that breaks up when it hits the surface of the fluid. The result is a ring of smaller bubbles (see movie 1).

http://www.nature.com/nature/newsvideo/nature09069-s2.mov

Bird and his co-workers spent the next three years developing the perfect theory of bubble bursting. They determined that only three factors affect bubble break-up: the surface tension of the bubble, the inertia of the fluid and the pressure of the gas trapped inside. Depending on these factors, a collapsing bubble might fold into two pockets of air instead of one — generating even more bubbles — or it might not form any offspring bubbles at all.

Party trick

The work is impressive in its scope, says Jens Egger, a mathematician at the University of Bristol, UK. "What's nice about this paper is that it's taken a small problem and found this beautiful structure," he says. Even daughter bubbles can burst and create more, even smaller bubbles, notes Eggers. "Self-similar structures just seem to be nature's way of making small things."

"Bubbles can be really useful in certain contexts and detrimental in others," Bird says. For example, bubbles are a constant worry in glass manufacturing because they can weaken material. In the oceans, however, bubbles can have a useful role by helping to convert salt into an aerosol, a crucial step in creating clouds. Small bubbles in particular seem able to project tiny particles into the air (see movie 2).

http://www.nature.com/nature/newsvideo/nature09069-s3.mov

Bird says the group's calculations might improve climate models and industrial processes. "Other than that, it's a cool party trick," he says, admitting that more than once he has rolled up a paper straw to demonstrate his PhD work to friends over a beer.

Meanwhile, Bird's work with bubbles is not yet done. He has just been awarded a one-year fellowship from the US National Science Foundation to continue his research. "I thought I was going to be done with bubbles, but no, it keeps going," he says.

References
Bird, J., de Ruiter, R., Courbin, L. & Stone, H. A. Nature 465, 759-762 (2010). | Article
 
PARIS: A planet named after ancient Egypt's Lord of the Dead is a place where human beings would be simultaneously boiled, poisoned and ripped apart by superstorms, astronomers reported on Wednesday.

The distant world, orbiting a bright star in the constellation of Pegasus 150 light years from Earth, is known officially as HD 209458b, but has been nicknamed Osiris, the god of the Egyptian underworld.

The label is especially fitting, given insights into the planet's climate system reported in the science journal Nature.

Osiris races around its yellow, Sun-like star at a distance of around seven million kilometres (4.37 million miles), less than a twentieth of the distance between Earth and the Sun, which means its “year” is just three and a half days.

On one side its surface is heated to a scorching 1,100 degrees Celsius (1,800 degrees Fahrenheit), although the other side is far cooler.

The planet's atmosphere is laced with poisonous carbon monoxide and prey to storm winds that blow from 5,000 to 10,000 kph (3,100-6,200 mph), says the paper.

“HD 209458b is definitely not a place for the faint-hearted,” quipped Ignas Snellen of Leiden Observatory, the Netherlands, who led a team of astronomers in the probe of the planet.

Snellen's team observed Osiris for five hours last August, using the European Southern Observatory's Very Large Telescope (VLT) in the desert of Chile.

The mission was to get a snapshot of the planet's atmosphere, using the VLT's infrared spectrograph, as the far-off world swung between its host star and Earth.

For three precious hours, the planet's transit in front of its sun caused telltale changes in starlight received by the Earth-bound telescope. These tiny alterations were then transcribed as signatures of atmospheric physics and chemistry.

A total of 462 exoplanets, worlds in solar systems other than our own, have been logged since the first was detected in 1995. None, though, is even remotely similar to our own planet, which is rocky and has water existing in liquid form.

HD 209458b is one of the most-studied exoplanets. It has previously been measured at 60 per cent the mass of Jupiter, the gas giant that is the biggest planet of our own star system.

But it is far hotter, given its searing proximity to its own sun. The very precise measurements of carbon monoxide shows that the gas flows at extraordinary speed from the hot side to the cool side of the planet.

“On Earth, big temperature differences inevitably lead to fierce winds and, as our new measurements reveal, the situation is no different on HD 209458b,”said team member Simon Albrecht. -AFP
 
Blood test can predict menopause: study

BEIJING, June 28 (Xinhuanet) -- Blood-testing could be used to predict early symptoms of menopause, according to news reports on Monday.

Experts from Iran said that their preliminary study could be a first step towards developing a method to help women when they want to have babies, according to the Associated Press.

Iranian scientists made blood test for 266 women in the 20-40 age group. Measuring the amount of anti-Mullerian Hormone, the doctors could tell how many eggs could be found in the ovaries.

The researchers used a mathematical model to calculate the time that women would go into menopause. Of the 63 females involved in the research, the experts predicted that was accurate to within four months.

Dr. Ramezani Tehrani, the leading expert at Shahid Beheshti University of Medical Sciences in Tehran said if their model was validated, then women in their 20s could provide a blood test to them and they could estimate the age of menopause.

(Agencies)

Editor: Xiong Tong
Blood test can predict menopause: study
 
universe.gif


The picture is the first full-sky image from Europe's Planck telescope which was sent into space last year to survey the "oldest light" in the cosmos.

It took the 600m-euro observatory just over six months to assemble the map.

It shows what is visible beyond the Earth to instruments that are sensitive to light at very long wavelengths - much longer than what we can sense with our eyes.

Researchers say it is a remarkable dataset that will help them understand better how the Universe came to look the way it does now.

"It's a spectacular picture; it's a thing of beauty," Dr Jan Tauber, the European Space Agency's (Esa) Planck project scientist, told BBC News.

Dominating the foreground are large segments of our Milky Way Galaxy.

The bright horizontal line running the full length of the image is the galaxy's main disc - the plane in which the Sun and the Earth also reside.

BBC News - Planck telescope reveals ancient cosmic light
 
Neck size could help ID childhood obesity

Measuring children's neck circumference could provide a quick, simple way to screen them for weight problems, a new study suggests.

Such screening is recommended by the U.S. Preventive Services Task Force, an influential panel sponsored by the government's Agency for Healthcare Research and Quality, starting at the age of 6. Right now, doctors usually use body mass index, or BMI, to gauge whether a child (or adult) is overweight or obese. But BMI, which is a ratio of weight to height, is not a good indicator of how much body fat a person has.

Because pounds due to excess body fat -- rather than larger bones or greater muscle mass -- are the health concern, researchers have been looking for more precise ways to gauge fat levels. One way is to measure waist circumference, which studies suggest is better than BMI alone in assessing abdominal fat and health risks, such as high blood pressure, diabetes and heart disease, in adults.

Another tactic is to measure neck circumference -- which, although less studied, seems to be a potential marker of obesity and health risks in adults.

The new study, published in the journal Pediatrics, looked at whether measuring neck circumference has any value in screening children for excess pounds and obesity.

Since BMI is not a precise indicator of body fat, adding a neck circumference measurement could improve childhood obesity screening, lead researcher Dr. Olubukola Nafiu, of the University of Michigan in Ann Arbor, told Reuters Health.

And compared with waistline measurements, measuring the neck would also be quicker and more comfortable for children, Nafiu said, since they can keep all their clothes on for the latter.

Neck circumference is also more consistent in comparison to waist size -- which can swell after a big lunch, for instance.

For their study, Nafiu and his colleagues measured weight, height, waist circumference and neck circumference in 1,102 children and teenagers ages 6 to 18 who were undergoing surgery at their center.

They found that neck circumference correlated well with both BMI and waist size in boys and girls, as well as younger children and teenagers.

The researchers also pinpointed "optimal" cutoff points for neck circumference that identified a majority of kids with a high BMI. For example, a 6-year-old boy with a neck circumference of greater than 28.5 centimeters - about 11.2 inches -- was nearly four times more likely to be overweight or obese, based on BMI, as a 6-year-old boy with a smaller neck circumference.

In addition to helping screen for obesity, the researchers note, neck measurements might also be useful for spotting kids at risk of sleep apnea, a disorder in which tissues at the back the throat temporarily collapse during sleep to create repeated stops and starts in breathing. Obesity, particularly excess weight in the upper body, is a risk factor.

Nafiu said that in earlier studies, he and his colleagues found that children with a high BMI were at relatively greater risk of certain post-surgery problems; they tend, for instance, to take longer to wake up from anesthesia because the drugs concentrate in body fat.

In the future, Nafiu said, the researchers want to look at whether measuring neck circumference before surgery can identify children at greater risk of such problems.

SOURCE: Neck Circumference as a Screening Measure for Identifying Children With High Body Mass Index -- Nafiu et al., 10.1542/peds.2010-0242 -- Pediatrics

Pediatrics, August 2010.
 
If the Earth Stood Still

Ever thought what would happen if the Earth stood still? here what the experts predict would happen!

Modeling the absence of centrifugal force
By Witold Fraczek, Esri

The following is not a futuristic scenario. It is not science fiction. It is a demonstration of the capabilities of GIS to model the results of an extremely unlikely, yet intellectually fascinating query: What would happen if the earth stopped spinning? ArcGIS was used to perform complex raster analysis and volumetric computations and generate maps that visualize these results.

The most significant feature on any map that depicts even a portion of the earth's ocean is the spatial extent of that water body. Typically, we do not pay much attention to the delineation of the sea because it seems so obvious and constant that we do not realize it is a foundation of geography and the basis for our perception of the physical world.

The line separating oceans from continents outlining the spatial extent of both land and water is the most fundamental contour. It is zero elevation because it signifies the sea level. Why is the sea level where we currently observe it? What controls the sea level? How stable are the forces that determine the sea level? This article does not refer to the climate change and the potential increase of the water level in the global ocean but rather to the geometry of the globe and the powerful geophysical energies that determine where oceans lie.

Sea level is—and has always been—in equilibrium with the planet's gravity, which pulls the water toward the earth's center of mass, and the outward centrifugal force, which results from the earth's rotation. After a few billion years of spinning, the earth has taken on the shape of an ellipsoid (which can be thought of as a flattened sphere). Consequently, the distance to the earth's center of mass is the longest around the equator and shortest beyond the polar circles. The current difference between the average sea level as observed along the equator and the distance to the earth's center of mass from the sea level at the poles is about 21.4 kilometers (km).
nospin_3.jpg
The gravity of the still earth is the strongest at the polar regions (shown in green). It is intermediate in the middle latitudes and weakest at the high altitudes of the Andes, close to the equator.
nospin_4.jpg
When global rotation stops, the massive oceanic water migration would cease and sea level would be at different locations, completely changing world geography.

What would happen if the earth's rotation slowed down and finally stopped spinning over a period of a few decades? ArcGIS lets us model the effects of this scenario, performing calculations and estimations and creating a series of maps showing the effects the absence of centrifugal force would have on sea level.

If earth ceased rotating about its axis but continued revolving around the sun and its axis of rotation maintained the same inclination, the length of a year would remain the same, but a day would last as long as a year. In this fictitious scenario, the sequential disappearance of centrifugal force would cause a catastrophic change in climate and disastrous geologic adjustments (expressed as devastating earthquakes) to the transforming equipotential gravitational state.

The lack of the centrifugal effect would result in the gravity of the earth being the only significant force controlling the extent of the oceans. Prominent celestial bodies such as the moon and sun would also play a role, but because of their distance from the earth, their impact on the extent of global oceans would be negligible.

If the earth's gravity alone was responsible for creating a new geography, the huge bulge of oceanic water—which is now about 8 km high at the equator—would migrate to where a stationary earth's gravity would be the strongest. This bulge is attributed to the centrifugal effect of earth's spinning with a linear speed of 1,667 km/hour at the equator. The existing equatorial water bulge also inflates the ellipsoidal shape of the globe itself.

nospin_5.jpg

The extent of a hypothetical northern circumpolar ocean over the territory of North America is shown. The orange color indicates areas with elevation higher than 3,000 meters above the level of the northern ocean. Red dots represent some of the biggest cities of the continent.

The bulge defines the final shape of the globe by establishing the uniform sea level in gravitational equilibrium, which is used as the standard reference for describing the shape of the earth. It is the geometry of this very shape that geodesists were trying to calculate for more than a century. Their efforts were finalized by the acceptance of the ellipsoid referred to as World Geodetic System 1984 (WGS84) by the international community in Washington, D.C., in 1984. The ellipsoid WGS84 approximates the shape of the earth more accurately than many other ellipsoids that were previously proposed.

If the earth stood still, the oceans would gradually migrate toward the poles and cause land in the equatorial region to emerge. This would eventually result in a huge equatorial megacontinent and two large polar oceans. The line that delineates the areas that hydrologically contribute to one or the other ocean would follow the equator if the earth was a perfect ellipsoid. However, due to the significant relief of both the continents and the ocean floor, the hypothetical global divide between the areas that hydrologically contribute to one or another ocean deviates from the equator significantly. Analogous to the well-known U.S. Continental Divide, this would be the border separating two giant hemispherical watersheds of the new circumpolar oceans. Interestingly, the highest point on this global divide would not be the highest altitude on the entire globe. The highest elevation of the global divide in the Colombian Andes would be about 12,280 meters, whereas the altitudes of the famous equatorial volcanoes of Chimborazo (Ecuador) and Kilimanjaro (Tanzania) would be 13,615 and 12,786 meters, respectively. Both volcanoes happen not to be located on the global divide line. The lowest point on the new global dividing line, with an elevation of 2,760 meters, would be situated southwest of Kiribati Island in the western Pacific.

Due to the unique relief of the earth's surface at the beginning of the slowdown, the most significant changes to the outline of land versus water would occur at the high latitudes of the northern hemisphere where the swell ocean would quickly expand over the flat and vast territories of northern Siberia and northern Canada. At the same time, changes to the continental outlines at low latitudes would be barely perceptible because (with a few exceptions) equatorial waters are deep, and a decrease in water level by a few dozen meters would not cause large areas of land to emerge. Toward the end of the slowdown period, when the main geographic features of oceans and land would have already adjusted to the ellipsoidal shape of the globe and the new distribution of gravity, relatively small changes would occur. This can be attributed to the ellipsoidal shape of the globe, which overwhelms the effect of the diversity of the earth's geographic relief.

Today, all three world oceans are connected. This creates a global ocean with basically one sea level. As a consequence of rotational slowdown, the outline of the global ocean would continuously undergo dramatic changes. Equatorial waters would move toward polar areas, initially causing a significant reduction in depth while filling the polar basins that have much less capacity. As regions at high latitude in the northern hemisphere become submerged, the areal extent of the northern circumpolar ocean would rapidly expand, covering the vast lowlands of Siberia and northern portions of North America. The global ocean would remain one unit until the rotation of the earth decreased to the speed at which ocean separation would occur. The interaction between the inertia of huge water bodies and decreasing centrifugal force would be very complicated. As the consequence of steady slowdown of earth's rotation, the global ocean would be gradually separated into two oceans. Obviously, the last connection will be broken at the lowest point of the global divide line, located southwest of the Kiribati Islands. Since the current western Pacific Ocean is a plane, land would emerge quickly because there would be no chance that water would be exchanged between the two circumpolar oceans after the initial split. The area of final separation between the two oceans would be the simultaneous emerging and drying of territory extending for hundreds of kilometers.

nospin_6.jpg
While gravity pulls more water toward the Arctic Ocean, the lowlands of Siberia and northern Canada would become submerged. The corresponding movement of water away from the equatorial region combined with the shallow continental shelf waters southeast of Asia and north of Australia will cause land to emerge.
nospin_7.jpg
A deepening Arctic Ocean would lead to the further expansion of water over the northern plains of Asia, Europe, and North America. Greenland and Antarctica, despite their high elevations, would become significantly smaller in size. New archipelagos emerge from the southern seas. The Great American Lakes, the biggest freshwater reservoirs in the world, dissolve into the ocean.

The slowdown would continue after the separation of the two oceans and cause further migration of the ocean water toward the poles. Surprisingly (despite Antarctica's elevation), the southern polar basin has a larger capacity than the northern one. Given the fixed volume of water in both hemispheres, the more capacious basin of the southern pole would result in an overall lower sea level than the northern ocean. According to volumetric calculation performed with the ArcGIS 3D Analyst extension, the difference between the sea level of the two oceans should be 1,407 meters. However, the data accuracy does not warrant this level of precision, so the elevation difference between the sea level of the two oceans used was 1,400 meters.

The series of maps illustationg this article depict the intermittent stages during this migration of the earth's oceans and changes in land extents, topographic elevation, and bathymetric depth caused by the decreasing speed of the earth's rotation. These maps demonstrate the intermediate stages of transitional geography from a rotating to a stationary world. They show the effects of the gradual reduction of centrifugal force from its current level to none, leaving gravity as the only force controlling the ocean's extent.

The actual slowdown of the earth's rotation has been observed, measured, calculated, and theoretically explained. As newer methodologies are developed and more precise instruments are constructed, the exact rate of the slowdown may vary between some sources. Reflecting this very gradual slowing, atomic clocks must be adjusted to solar time by adding a leap second every so often. The first leap second was added in 1956.

nospin_8.jpg
All Antarctica would be under water at this point. The north polar waters and the water over the vast, recently submerged territories in Siberia and Canada would be getting deeper. At the same time, equatorial waters would be getting more shallow.
nospin_9.jpg
Large land areas near the equator continue growing and join with each other. By now, nearly all of Canada, Europe, and Russia are covered by a northern circumpolar ocean.

Most scientists agree that the solar day (related to the speed of rotation) is continuously getting longer. This minimal increase of the day length is due mainly to the oceanic tidal friction. When the estimated rate of the slowdown was projected back to past geologic eons, it showed that the length of a day was several hours shorter than today.

Consequently, during the Devonian period (400 million years ago), the earth rotated about 40 more times during one revolution around the sun than it does now. Because the continents have drifted significantly since that time, it is difficult to make estimates of the land versus ocean outlines for that era. However, we can be certain that—with a faster spinning speed in the past—the equatorial bulge of oceanic water was much larger then than it is today. Similarly, the ellipsoidal flattening of the earth was also more significant.

nospin_10.jpg

As the last water connection between the two large neo-oceans is broken, an equatorial megacontinent is formed. Ocean areas in proximity to the continent are becoming more shallow while the waters of the polar areas are getting deeper and deeper. Former abyssal plains and oceanic trenches become inland seas within the new continent.

The influence of the rate of the earth's rotation has a dominant effect on the geometry of the globe, in terms of the globe's overall shape as well as the outline of the global ocean. The earth's physical relief is only a secondary factor controlling the delineation of oceans. The slowdown of earth's rotation will continue for 4 billion years—as long as we can imagine. The slowdown infinitesimally—but steadily—changes the globe's geometry and makes it dynamic. The net result of these dynamic adjustments is that the earth is slowly becoming more and more like a sphere. However, it will take billions of years before the earth stops spinning, and the gravitational equipotential creates a mean sea level that is a perfect sphere.

About the Author
Witold Fraczek is a longtime employee of Esri who currently works in the Application Prototype Lab. He received his doctorate in the application of GIS in forestry from Agricultural University and master's degrees in hydrology from the University of Warsaw, Poland, and remote sensing from the University of Wisconsin, Madison.
 
Seeking a Better Living Laboratory, Researchers Create the First "Artificial" Ovary

While trying to create a better synthetic environment in which to study how ovarian cells develop and interact, a Brown University researcher and her colleagues have created the first working artificial ovary. Using special “3-D Petri dishes” and samples of donor cells, the team has already created an artificial organ that has carried human eggs through to maturity.
To do so, they had to coax the three main cell types found in the human ovary into particular three-dimensional structures. The means for doing so were found in a special moldable agarose gel, dubbed 3-D Petri dishes, that encourage cells to grow into certain shapes and structures.
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Science, Clay Dillow, fertility, health, medicine, ovaries, reproductive health, synthetic biologyThe researchers first created honeycomb-like structures out of donated theca cells, one of the main cell types found in the ovary. Once in a honeycomb arrangement, the voids in the structures were filled in with granulosa cells along with human oocytes (those are the eggs, you’ll recall from biology class). In just a few days, the artificial cellular structures had enveloped the egg cells, essentially becoming a functioning ovary.
The eggs then matured from a young state to full maturity, demonstrating that the structures aren’t only good for experimenting with ovarian cells but also for clinical use. So while the artificial organ can be used as a living laboratory for research on egg development and ovarian function, it could also be used clinically to bring immature eggs to term outside the bodies of women facing cancer treatments or other fertility-hindering treatments.

Seeking a Better Living Laboratory, Researchers Create the First "Artificial" Ovary | Popular Science
 
NASA's Next-Gen Spacelaunch System Could Launch Scramjets from a Massive Railgun


With the Space Shuttle program winding down, both NASA and several commercial ventures are developing next-gen rocket technology that will hurl the next iteration of space vehicles into the sky. But NASA acknowledges that rockets aren’t the only – or even the best – way to get into space.
Engineers at the space agency’s Kennedy Space Center in Florida are exploring future space launch schemes that could see spacecraft flung into the heavens by a massive railgun or launched to the upper atmosphere aboard supersonic scramjets. Or, even cooler: both.
If space launches are anything, they’re expensive. As such, launch vehicles that are reusable (like the space shuttles) are key to keeping costs under control. One such scheme for reusable launch craft involves ferrying payloads to the upper limits of the atmosphere aboard scramjets, those air-compressing, high-speed jets with theoretical top speeds more than four times faster than the fastest air-breathing jet engines.
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Technology, Clay Dillow, aviation, nasa, railguns, scramjets, Space, spaceflightIn such a scheme, a payload vehicle (holding, say, a satellite) would piggyback to high altitude aboard the scramjet, which in theory could reach near-orbital speeds. From the upper atmosphere, the payload vehicle would launch from the scramjet propelled by something akin to the second stage of a booster rocket, putting the satellite or even a manned vehicle into orbital space without the incredible thrust needed to launch it from the ground.
But how does NASA plan to get the scramjet to the supersonic speeds necessary for sustained flight? Picture a huge railgun rising from the ground at Kennedy Space Center. Using an electrified track stretching for miles, the track would use a magnetic field (or perhaps gas propulsion, or even magnetic levitation – this stuff is all still very much on the drawing board) to accelerate scramjets to otherworldly speeds without expending the huge amounts of chemical energy needed to fire a rocket booster. Once a scramjet is moving fast enough, the jet engine would take over and propel it spaceward.
For now rockets are still NASA’s principle launch vehicles, so don’t expect any spacecraft-hurling railguns or regular hypersonic flights to the edge of space in the immediate future. But these technologies already exist in some nascent form or another. Both NASA and DARPA have been dabbling in scramjet technology for years, creating a vast body of knowledge and data for engineers to build upon. For their part, railguns have been around for nearly a century. All the technologies involved need further refinement, but none are out of reach.
Put another way: NASA is dreaming up massive railguns to launch hypersonic space vehicles into the atmosphere at blinding speeds. What's not to like?


NASA's Next-Gen Spacelaunch System Could Launch Scramjets from a Massive Railgun | Popular Science
 
second that.

We need subfolders like space, material, living science, Chmistry, electronic/electrical etc.

Third (or may be fourth) that. But until that happens, we'll have to do without it.

I'm an amateur astronomer and am glad that a lot of non-astronomers found the following useful when I shared it with them, because it was written for them. So here we go.

"Isn't That Crescent Too Fat?"

You bet it is not!

Unfortunately, almost every year many of our people are thrown into doubts about the lunar date when they first see the lunar crescent and find it "too thick" and staying above the horizon for "too long", even though both of these factors do not have a fixed relationship with the date of the lunar calendar. This is because of many factors. Without getting technical, I'll try to explain two of the more important aspects which determine how thin the Moon of the first can be.

* The tilt of the crescent (or put another way, the direction of the crescent's cusps)
* The speed of the Moon in its elliptical orbit

To avoid the discussion becoming uninteresting and too complex for the layperson, we'll not go into "why" these factors influence the appearance of the crescent. We'll just talk of the result they have.

Before we proceed, please bear in mind a simple rule: the mere presence of the crescent above the horizon is not what matters; being able to actually sight it does.

Aspect # 1:

1(a): When the crescent's cusps are pointed steeply to a side, a younger Moon is very low in the horizon and sets soon after the Sun does - while the evening sky is still light. Depending on your latitude (not elevation/altitude) and the atmospheric conditions (haze etc.), it can be difficult or even impossible to see such a crescent. When the crescent first becomes visible on the next evening, it will naturally be thicker. Thus, when the cusps are steeply inclined, the crescent of the first can be comparatively thicker. Example of a steeply inclined crescent: 1st Shawwal 1431 (10th September 2010)

Mohammad-Mehdi-Asgari-moon-2_1284141852_med.jpg


1(b): When the cusps point almost upwards, even a very young thin crescent can be much higher and set much later than the Sun. If the sky is not cloudy, we can easily see such a Moon. Thus, a "balanced" crescent on the first of a lunar month can be remarkably thin.

For a given month, the direction of the cusps depends on the observer's location on the Earth, north or south of the equator.

Many of us saw how inclined the Shawwal 1431 crescent was, so its comparative thickness was only natural. The crescent of Safar 1432 (January 2011) will have cusps pointing almost upwards, and all of us who look towards the west at dusk will see how extraordinarily thin the Moon of the first will be. But it might be that very few Pakistanis will actually look at the sky because it won't be Ramazan or Shawwal or Zil'haj!

Example of a "balanced" crescent (Matt Bendaniel, Oct 15, 2001):

crescentmoon_bendaniel_m.jpg


Aspect # 2:

Did you know that the size of the lunar disk varies each month? It does so because the lunar orbit is elliptical (oval).

Anthony-Ayiomamitis1_strip.jpg


These are two real photos, and not simulations, shot at the same magnification by Anthony Ayiomamitis of Athens, Greece. Surprised to see the size difference?

Also, the Moon's orbital speed is not constant. When the lunar disk is at its smallest (apogee), the Moon is moving around Earth at is slowest. When the disk is at its biggest (perigee), the Moon is orbiting Earth the fastest. Now let us consider the effect of apogee and perigee on the crescent.

2(a): When New Moon Occurs At Apogee

The Moon is orbiting at its slowest due to which its phase is thickening at its slowest. If the crescent is not seen on a particular evening, it will still not be much thicker 24 hours later when it is first sighted on the next evening. Thus, near apogee, the crescent of the first is thinner.

2(b): When New Moon Occurs At Perigee

The Moon's phase is increasing at its fastest now. If on a particular evening the crescent is not seen, it will be comparatively much fatter just 24 hours later. Thus, near perigee, the crescent of the first is comparatively thicker.

The Moon of Shawwal 1431AH was not only steeply inclined but was also at perigee. So it was very low in the horizon on 9th September due to the first factor and just 24 hours later it had rapidly thickened due to the second factor.

Q: A layman wants to know about the next Moon's visibility prospects but does not know what the current Sun-Moon-Earth geometry is. What should he do?
A: He can choose to either become an astronomer or consult the experts. I've no affiliation with this site, but renowned experts, both Muslim and non-Muslim, trust and contribute to it: MoonSighting.com

I have tried to explain all this in the layman's terms. For instance, instead of using obscure (albeit quantifiable and technically much more useful) terms like ecliptic latitude, relative azimuth, elongation etc., we talked of the "tilt of the crescent". It might still be difficult for some to comprehend the concept. Nevertheless, I can only hope that, say, next Ramazan, at least those who have read this would be confident that the "fat crescent over there" indeed heralds the first day of fasting. The future rests in God's hands.
 
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Do you guys know that laser thing from which we can produce electricity??

Too lazy to find the name..
 
A small asteroid will likely pass very close to Earth this week Tuesday. Astronomers are still tracking the object, now designated as 2010 TD54, and various estimates say it could possibly come within anywhere from 52,000 km (33,000 miles) to 64,000 km (40,000 miles) on October 12, with closest approach at approximately 11:25 UT. Information on the IAU Minor Planet Center website lists the object as coming with 0.0003 AU. The size of the object has not been determined, but estimates say it is likely smaller than 10 meters. We’ll provide an update as soon as more information is available.

UPDATE: Don Yeomans, Manager of NASA’s Near-Earth Object Program Office replied to an inquiry about the object and said the newly discovered NEO 2010 TD54 is approximately 5-10 meters in size, and is now predicted to pass about 46,000 km from Earth’s surface at about 07:25 EDT (11:25 UT) on Tuesday, Oct 12, 2010. It was discovered by Catalina Sky Survey on Saturday morning.

“Only 1 in a million chance of an impact,” Yeomans said, “and even if it does impact, it is not large enough to make it through the Earth’s atmosphere to cause ground damage.”

The object may be visible to amateur telescopes as a 14th magnitude “star” — it will be traveling through the constellations Pisces and Aquarius.

Breaking News: Small NEO Could Pass Within 60,000 km of Earth on Tuesday | Universe Today
 

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