Solar Eclipse on July 22 May Be Most Viewed Ever

Rebecca Carroll, National Geographic News 20 Jul 09;

A total solar eclipse passing over some of Earth's most densely populated regions on Wednesday, July 22, 2009, may become the most viewed eclipse ever.

People across central India and in parts of Nepal, Bangladesh, Bhutan, and Myanmar will briefly find themselves in daytime darkness before the solar eclipse proceeds into China.

Most of the best viewing opportunities are in China, where some 30 million people will be able to witness the solar eclipse in the coastal cities of Shanghai and Hangzhou alone, according to veteran eclipse scientist Jay Pasachoff of Williams College in Massachusetts.

(Related pictures: "Solar Eclipse 'Ring' Seen Over Indonesia.")

The eclipse will then continue east, passing over Japan's Ryukyu Islands before reaching its maximum duration point over the Pacific Ocean, where the sun will be completely blocked by the moon for 6 minutes and 39 seconds, according to NASA scientist Fred Espenak.

Thousands of overseas tourists and potentially millions of Chinese are flocking to areas along the eclipse path, where hotels are charging higher rates, according to Chinese media reports.

The July 2009 total solar eclipse is expected to have the longest duration of totality in the 21st century, experts say, and should give Pasachoff plenty of data to keep him and his team busy for months.

Pasachoff will see only about five and half minutes of totality from a site in eastern China, but "once you have five minutes-plus of totality, the extra minute that we could have [seen] is not significant," he added.

Preparation

Pasachoff and his team will observe the solar eclipse from a remote hotel at an altitude of about 3,000 feet (900 meters) on Tianhuangping, a mountain outside the Chinese city of Hangzhou. The location sits above pollution that could obstruct a full view of the eclipse.

He chose the site years in advance so he could witness the longest totality from the Asian mainland. Teams of astronomers from around the world have already joined him at Tianhuangping.

Pasachoff, a National Geographic Society Committee for Research and Exploration grantee, will witness his 49th solar eclipse and 29th total eclipse since he began chasing the sun on October 2, 1959. (The National Geographic Society owns National Geographic News.)

"We brought about half a ton of equipment and picked up an equal amount borrowed here from our Chinese colleagues, so there is a lot to get ready," he added.

(Related: "Eclipse Expert Makes Hot Finds in Sun's Darkest Hour.")

Solar Mystery

Pasachoff wants to understand why the sun's corona—gas that extends millions of miles out from the sun—is millions of degrees hotter than the sun. The sun is just about 6,000 degrees Fahrenheit (3,300 degrees Celsius).

"Somehow energy has been put up into the corona from lower down, heating the gas, and we'd like to see how that happens," he said.

Scientists believe the coronal phenomenon has to do with the sun's magnetic field, and Pasachoff is looking to identify vibrating magnetic waves that move from the sun out into the corona.

(Related: "'Corkscrew' Waves Seen on Sun -- Keys to Solar Mystery?")

Scientists can't usually see the corona from Earth because its light is fainter than the blue sky created by our atmosphere.

Furthermore, instruments attached to space satellites can't isolate all areas of the corona because the sun and the light it scatters are too bright.

The only time certain observations are possible is when the moon blocks out the sun, creating a darker sky, which highlights the coronal light around the sun.

Although the sun is about 400 times bigger than the moon, it's also about 400 times more distant. So from the ground, the moon appears to be just a little bigger than the sun.

Shadow Chasers

The sun's disappearing act attracts so-called eclipse tourists, who travel the world to watch solar eclipses which happen between two and five times a year, though total solar eclipses are less frequent.

(See solar eclipse pictures.)

Rollie Anderson, a retired actuary from St. Louis, Missouri, is in China now to watch his 14th eclipse.

"The cosmic coincidence that the sun and moon both appear in the sky as the same size, and then, on top of that, they line up every now and again. … Just the very idea of that is pretty mind-blowing," he said.

"As you get to the last several minutes before totality, that's when your eyes actually start noticing things getting dark around you, and you can feel the air cooling," he said. "It gets really dark and totality appears, and that's when it gets most spectacular."

"You see a black hole in the sky where the sun used be, and if there are birds around, they may stop chirping, because they think it's night."

Chasing eclipses has also allowed Anderson and his wife to see the world.

"It's kind of an excuse to see whatever the part of the world the eclipse happens to be in."

Crowds flock to Bangladeshi town for solar eclipse
Yahoo News 20 Jul 09;

DHAKA (AFP) – A tiny town in northern Bangladesh is braced for a rare taste of mass tourism as thousands of people pour in to witness a full solar eclipse on Wednesday.

The event -- the longest total solar eclipse of the 21st century -- will be visible in a narrow corridor across north India, eastern Nepal, north Bangladesh, Bhutan and China.

Banamali Bhoumik, the district administrator of Panchagarh town, told AFP that 20,000 visitors were expected and he encouraged residents to "vacate their houses and share beds" to accommodate the influx.

"Already people are rushing in from every corner of the country," he said. "We have made huge preparations, including offering cheap meals and setting up special prayer halls."

Hotels, guest houses and government bungalows were already full, he added.

Total solar eclipses occur when the moon comes between the Earth and the sun, completely obscuring the sun.

The excitement this time around is largely due to the unusually long duration of the instant of greatest eclipse, or "totality" -- when the sun is wholly covered.

At its maximum, this will last six minutes and 39 seconds -- a duration that will not be matched until the year 2132.

"There is tremendous enthusiasm centering on the eclipse," F.R Sarker, the head of the Bangladesh Astronomical Association, said.

"This will be the only total solar eclipse Bangladeshis can see in the next 105 years. We are lucky it's happening in our time."

People in the capital Dhaka will be able to see a 93 percent eclipse, Sarker said.

Solar eclipse: Of celestial mechanics and the Eye of God
Richard Ingham Richard Ingham Yahoo News 20 Jul 09;

PARIS (AFP) – Total solar eclipses have struck awe or fear into hearts for millennia, but scientists are more interested in the unusual mathematics behind the gold-and-indigo lightshow.

Superstition has always haunted the moment when Earth, Moon and Sun are perfectly aligned. The daytime extinction of the Sun, the source of all life, is associated with war, famine, flood and the death or birth of rulers.

Desperate for an explanation, the ancient Chinese blamed a Sun-eating dragon. The Vikings believed the culprits were two giant wolves, Skoll and Hati, which chased the Sun around the sky. Among Indians in South America, an eclipse was simply, terrifyingly, "the Eye of God."

But a remarkable act of celestial geometry explains it all.

When the Moon glides between Earth and the Sun, it casts a cone-shaped shadow, called an umbra, that races from West to East.

The Sun is 400 times wider than the Moon, but it is also 400 times farther away. Because of the symmetry, the umbra, for those on the planetary surface, is exactly wide enough to cover the face of the Sun.

At an eclipse's height, a halo of gold, called a corona, flares around the darkened lunar disc, while the sky turns an eerie dark blue, disorienting birds and causing bats to emerge from their roosts in the belief that night has fallen.

Total solar eclipses are exceptional events, and the one that crosses Asia on Wednesday is especially so.

If the clouds hold back, it could be the most-watched eclipse in history, for its path of totality traverses the world's two most populous countries, China and India.

People living outside totality, from Japan in the north to parts of Indonesia in the south, will be in the penumbra, or partial shadow, which means a "bite" seems to have been taken out of the Sun.

The lunar shadow will first strike the Gulf of Khambhat, off western India, at 0053 GMT, taking eight minutes to cross the centre of the country before entering northern Bangladesh and the eastern tip of Nepal.

It then slices through some of China's biggest cities, including Chengdu, Chongqing and Wuhan, before arriving at Shanghai, a city of 20 million souls.

"This may be the most people that have ever been in the Moon's shadow at once," say NASA eclipse experts Fred Espenak and University of Manitoba meteorologist Jay Anderson.

The umbra then flits across the western Pacific, where at one point the path of totality will be 258 kilometers (161 miles) wide, while the maximum duration of totality will be six minutes, 39 seconds.

By eclipse standards, this is "a monster," Espenak and Anderson estimate in the US magazine Sky & Telescope. We will have to wait until 2132 before the totality duration is beaten.

A total solar eclipse usually occurs every 18 months or so. Any given spot on Earth's surface will host a total eclipse on average once every 375 years.

Until now, the most-watched eclipse occurred on August 11, 1999, when the umbra raced from Britain, across Western Europe, part of the Middle East and India.

The last total solar eclipse was on August 1 2008, and also crossed China.

The next will be on July 11 2010, but will occur almost entirely over the South Pacific, where Easter Island -- home of the legendary moai giant statues -- will be one of the few landfalls.

That will be wonderful news to "eclipse junkies," an eclectic army that pursues total eclipses around the world, sometimes hiring seats on planes or ships to get the best view.

+ SAFETY FIRST: Eclipses, even partial ones, should NOT be viewed with the naked eye or through binoculars, a telescope, beer bottle or photographic film, as this can permanently damage the retina. Observers should use proper optical filters such as welding-goggle glass, eclipse spectacles or a solar projection kit for their telescope. The safest way to view is on television or the Internet.