solar eclipse--- From fear to fascination

Zeus, father of the Olympians,
made night from mid-day,
hiding the light of the shining Sun,
and sore fear came upon men.
Archilochus ― Greek poet
(Refers to the eclipse of April 6, 647 B.C. )

SUPERSTITION…SCIENCE…FASCINATION…
For centuries people feared it, made sacrifices to it, wailed over it. Today we run to greet it - a total eclipse of the sun.
Eclipses of the Sun and Moon have always left a deep impression on their viewers. The loss of the Sun, the bringer of life for ancient people, was considered a bad omen. Many ancient people―including those in the Caribbean and the islands of the Pacific― believed that during an eclipse a monster or dragon was eating the Sun. The time of an eclipse was one of prayers, sacrifices, and noise as they attempted to make the dragon drop its prey―and the dragon always did!

October 22, 2134 B.C. ― Hi and Ho, The Royal Astronomers
Predicting an eclipse was a duty of ancient Chinese astronomers. The earliest written record of a total solar eclipse comes from China. In 2134 B.C. two royal astronomers, Hi and Ho, knew that an eclipse was due. According to legend, on the day of the eclipse they were too drunk to perform the rites of chanting, beating drums and shooting arrows at the dragon that was devouring the Sun. When the eclipse took place the emperor ― also known as the 'Son of the Sky'― was caught unprepared. Advance notice was required to dispatch the archers to frighten the dragon consuming the sun. The emperor ordered Hi and Ho beheaded for their sins.
"Here lie the bodies of Ho and Hi,
Whose fate, though sad, is risible;
Being slain because they could not spy
Th' eclipse which was invisible."
(Author unknown)

1900 B.C. Stonehenge ― An Ancient Computer?
In Southern England stands an awesome arrangement of prehistoric ruins and stones that have been the subject of countless studies, poems and legends. Speculation on the study of Stonehenge have continued unabated from the time that it was first mentioned in the literature shortly after the Norman Conquest (1066). Evidence indicates that Stonehenge, built during the same era as the Great Pyramid of Egypt, was a brilliantly conceived astronomical observatory. Certain holes were apparently used as an eclipse predictor.

June 15, 763 B.C.―A Biblical Eclipse
"And on that day," says the Lord God, "I will make the Sun go down at noon, and darken the Earth in broad daylight." This eclipse is confirmed by an Assyrian historical record known as the Eponym Canon. (Amos Chapter 8, Verse 9 - Old Testament)

May 28, 585 B.C.―An Eclipse Ends a War
The most famous solar eclipse of classical times occurred in the midst of a battle between the Medes and the Lydians. The two armies were locked in battle when "the day was turned into night." (This eclipse had been predicted by Thales, the Greek astronomer and philosopher, but the prediction was probably not known to the warring nations.) According to the Greek historian Herodotus, both sides regarded the eclipse as an omen and immediately ceased hostilities, thereby ending a six year war. They signed a peace treaty and cemented the bond between their nations with a double marriage.

April 10, 628 A.D.― Death To the Empress
The death of Empress Suiko of Japan was attributed to the total eclipse of April 10, 628 A.D.

May 1, 664 A.D. ―Death To the King
"In this year the Sun was eclipsed … and Earcenbryht, the King of the Kentish people died and his son Ecgbryht succeeded to the Kingdom" (The Anglo Saxon Chronicles)

May 5, 840 A.D.― An Eclipse Ends a Life
The appearance of an eclipse was often thought to be supernatural and a sign of impending calamity.
Emperor Louis of Bavaria, son of Charlemagne, and head of a vast empire supposedly died of fright during the 5 minutes of eclipse totality he witnessed in 840 A.D. His three sons immediately fought over succession to his throne - a battle which ended three years later with the historic Treaty of Verdun and the division of the empire into what is today France, Germany and Italy.

August 9, 975 A.D. ―A Japanese Amnesty
"The Sun was eclipsed… It was the colour of ink. All the birds flew about in confusion and the various stars were all visible… There was a general amnesty on account of the eclipse."

February 29, 1504 ― Columbus and the Moon's Eclipse
In 1503 Christopher Columbus found himself marooned in the small bay of Santa Gloria, Jamaica. When the Indians refused to supply food, in exchange for trinkets, Columbus devised a plan to trick them. He had aboard the Capitana a copy of Johannes Muller's Calendarium published around 1474 which contained predictions of lunar eclipses ― one of which was scheduled for February 29, 1504. He arranged an evening meeting with the natives to coincide with the beginning of the eclipse and announced that God would show his displeasure towards them by taking away their moon. Right on cue a dark shadow began to pass over the face of the moon. When the frightened Indians pleaded for its restoration Columbus retired to 'confer' with God - probably his hourglass to check out when the total phase was due. The moon ― and the food supply were promptly restored.

1560 ―An Eclipse Postponed
In The announcement of a forthcoming eclipse in France caused many Frenchmen to panic.
They fought one another to be first in line for the confessional. One beleaguered parish priest tried to calm the populace by announcing that since there were so many waiting to confess a decision had been made to postpone the eclipse for two weeks!

1600's―Flaming Arrows
The Chippewa Indians of North America thought the sun's flame was being extinguished during an eclipse, so they fired flaming arrows into the sky to re-ignite it.

April 1, 1764 ―Eclipse, The Racehorse
One of the most famous racehorses was named "Eclipse" because it was born at the time of the annular eclipse of 1764. The Eclipse Awards, named after that horse, are given in the U.S to thoroughbred champions.

October 27, 1780―The Harvard Expedition
During the Revolutionary War the first American eclipse expedition was organized by Harvard and led by Samuel Williams, professor of mathematics and natural philosophy. Alas, the site of the projected scientific expedition lay in enemy territory. The western portion of Penobscot Bay was the only place in the path of the eclipse accessible by a ship large enough to carry the group's heavy scientific equipment.
John Hancock, the speaker of the House, pleaded with the British commander at Penobscot Bay to make the American expedition possible. Addressing the commander as a "Friend of Science," Hancock wrote: "Though we are political enemies, yet with regard to Science it is presumable we shall not dissent from the practice of all civilized people in promoting it…" A special immunity agreement was negotiated with the British so that the scientists could work unharmed.
The Harvard expedition, after all their efforts didn't see the eclipse because they chose a site outside the path of totality!
In 1980 a group of Harvard students and professors traveled to Maine to reenact William's experiment. They used identical instruments and maps used by the original expedition in 1780 ― instruments which performed flawlessly and maps which were amazingly accurate. Williams had erred in his calculations of latitude. He had set up his instruments thirty miles farther south than astronomical tables indicated he should. The expedition that had managed to make a war step aside for the sake of science missed witnessing totality because of a mathematical miscalculation.

The Eclipse Of The Sun, 1820 ― An Eclipse in Literature
High on her speculative tower
Stood Science waiting for the hour
When Sol was destined to endure
That darkening of his radiant face
Which Superstition strove to chase,
Erewhile, with rites impure…
William Wordsworth

1851―The Corona Photographed
During totality the first successful photograph was taken of the solar corona. Early eclipse observers were able to see the sun's extensive, pearly-white corona surrounding the obscuring disk of the moon. The daguerreotype proved that prominences were in fact part of the sun rather than of the moon ― as early observers had tended to believe.
Sept 7, 1858― Olmos Peru
The midday disappearance of the sun brought the citizens of Olmos to their knees. Church bells rang - intending to drive away the evil spirits from the area. The resemblance of the corona was so similar to the halos which encircle the heads of the Savior and Madonna ― they perceived the eclipse to be a manifestation of the divine presence.

1868―Helium Discovered During Eclipse
Traces of a previously unknown element, helium, were detected on the sun during this eclipse. The two English discoverers recommended the new element be named helium, after the Greek helios, meaning the sun. In 1895, 27 years after it was discovered on the sun, helium, the second most abundant element, was recognized on the earth itself..

1878 ―The Eclipse and Thomas Edison
In 1878 Thomas Edison traveled to Wyoming to view a total eclipse. He set up his scientific instruments in a chicken coop but as the Sun dimmed the chickens came in to roost.
The Inventor spent so much time fighting chickens that he had only a few seconds of the more than three minutes of totality to make his observations.

1887 ―Volcano Eclipses the Eclipse
A United States eclipse expedition set up their elaborate instruments in Yokohama, Japan under perfectly clear skies. An hour before the eclipse was to occur a nearby volcano erupted belching forth large volumes of smoke and steam which obscured the sun until the eclipse was over.

1889 ―Mark Twain's Fictional Eclipse of June 21, 528
The hero of Mark Twain's novel "A Connecticut Yankee in King Arthur's Court" used the ignorance of eclipses to save his life. The Connecticut Yankee, Hank Morgan, is struck unconscious in a quarrel and wakes up in King Arthur's England of 528 A.D. He escapes being burned at the stake by "predicting" a solar eclipse. Morgan, claiming magical powers over the sun, bargains for his life in exchange for restoring daylight. King Arthur accepts - and the sun is restored.

1890 ― "Wild beasts and Savages"
A U.S. scientific eclipse expedition departed from New York's Navy Yard to the West Coast of Africa to bring back much needed information. They unloaded their provisions and set up their instruments on the beach― some of which were so heavy they required thirty to forty sailors to lift and carry them. A voluntary group of marines had been enlisted to guard the camp from "wild beasts and savages" until the eclipse was over and the scientists returned safely to their vessel.

May 29, 1919―The Eclipse and Einstein's Theory
This eclipse of the sun was used to dramatically confirm Einstein's Theory of Relativity. The experiment sought to test his prediction that the speed of light would be slowed slightly by powerful gravity.

January 24, 1925―A Typical Day in Manhattan
One of the most memorable eclipses for the northern United States, occurred at 9:11a.m. on January 24, 1925. It was calculated that totality would sweep across Manhattan. Many were disappointed, however, since New Yorkers above 80th Street witnessed totality while those below 80th Street saw a partial eclipse.

1948―Korea … An Election Postponed
National elections scheduled in May in Korea were postponed because a total eclipse was to occur on the date originally set for the balloting.

1966―Hindu Pilgrims, Gemini 12 Astronauts and An Eclipse…
In a study of contrasts, in 1966 the first picture of a total eclipse from outside the Earth’s atmosphere was taken by the crew of astronauts aboard Gemini 12. Meanwhile, in India, Hindu pilgrims by the thousands plunged themselves in sacred bathing tanks, hoping for protection from demons.

March 7, 1970―Eclipse, Virginia ― "Not In Our Backyard… "
The town fathers of Eclipse, Virginia said 'no, thank you' to Ted Pedas and Phil and Marcy Sigler who planned to stage an Eclipse'70 Festival in Eclipse, Va. ― a town which fell within the 80-mile wide eclipse path.
Eclipse frolicking on the banks of the Chukatuck river? "Not so fast," said the locals, who demanded a security check at the drawbridge of all incoming 'heliophiles'. Contract negotiations broke down over the provision that Pedas-Sigler would not admit into Eclipse, Virginia persons who advocated the "overthrow of the federal government," were "disrespectful to the flag" or had long hair.
The path of totality for the 1970 eclipse moved northward from Mexico and at Norfolk it jutted out to sea passing over Nantucket. Efforts to stage the eclipse festival on the Massachusetts island met with strong opposition. An influx of 'Woodstock-type' hippies" paying homage to the eclipse, and their organizers, were persona non grata . While retreating from Nantucket, via ferry, the Pedas-Sigler entrepreneurs had an idea. Why not charter the ferry on which they were sailing ― or a ship ― and sail it into the path of an eclipse?
The idea of intercepting totality at sea was born. The cosmic-thinkers put in a wake up call for the eclipse of July 10, 1972.

1972―World's First Eclipse Cruise is Launched; Destination ―Totality!
In 1972 the world's first eclipse cruise Olympia's Voyage to Darkness '72 set sail from New York with 834 passengers (and one cat, Penny Nicol) to achieve a spectacular rendezvous with eclipse totality 900 miles in the North Atlantic. The ship had positioned itself under a 'hole' in the sky avoiding the inclement weather which clouded out land based eclipse observers. The advantage of the Pedas-Sigler eclipse cruise was "maneuverability" and the utilization of weather satellite data to position the ship under clear skies.

Popularizing the 1972 eclipse ― Carly Simon ― You're So Vain
There was an explosion of publicity surrounding the launching of Eclipse'72, the world's first shipborne eclipse adventure. The notion of basking in the moon's shadow was featured in the press with trendy headlines such as Moon Game for Jet Set, A Cruise Is Where the Eclipse Is At, and Attention: Everyone on Deck to View the Eclipse.
"You flew your Learjet up to Nova Scotia to see the Total Eclipse of the Sun," Carly Simon said in her 1972-73 #1 Billboard hit You're so Vain which captured the media's fascination with the solar eclipse of July 10, 1972. (By the way, the eclipse in Nova Scotia was all but clouded-out. Had Carly Simon's eclipse chaser opted for the eclipse bound Voyage to Darkness'72 he would have evaded bad weather to intercept the eclipse at sea.)
Although scientists have travelled to eclipses for over 200 years, their expeditions were for scientific observation. The hardships of travel to remote areas where eclipses normally occurred, the expense, and the risk of being 'clouded-out' discouraged the pursuit of the eclipse to all but serious astronomy buffs.
The 1972Voyage to Darkness Pedas-Sigler eclipse cruise proved to be the benchmark for conveying large numbers of enthusiasts and professional astronomers to the best vantage point to intercept eclipse totality.
The eclipse scheduled for August 11, 1999 will be the most widely observed eclipse in history. In addition to being easily accessible by land, numerous eclipse cruises are scheduled to transport thousands of viewers into its path.

1973―Canberra and Cunard Adventurer Rendezvous with Totality
On June 30, 1973 the Canberra―Voyage to Darkness'73 with 2600 people on board, rendezvoused off the African coast with the longest eclipse (7 minutes) in modern times and sailed onto the front page of The New York Times. The prolific science writer and shipboard lecturer Isaac Asimov recorded his experience in his autobiography In Joy Still Felt
To accommodate those waitlisted for the sold out Canberra the organizers chartered a second ship Cunard Adventurer―Caribbean Eclipse'73 which, with 800 passengers aboard, intercepted the June 30, 1973 eclipse 1200 miles in the mid-Atlantic.

1973―Rescue-At-Sea
A dramatic rescue at sea aboard the Canberra followed the eclipse. Passengers and students combined their skills to improvise a defibrillator for emergency treatment of a stricken seaman who was removed from a freighter in the mid-Atlantic. Walter Sullivan documented the rescue-at-sea in The New York Times. To assemble the instrument the passengers used capacitors from the ship's antenna system, plates from a television camera tripod, screwdrivers with insulated handles, diodes from the kit of a Florida skywatcher and power determinations from a passenger's pocket calculator.
(NOTE: Another rescue-at-sea occurred in the South China Sea aboard the Asian'95 Voyage to Darkness. An Indonesian fisherman had fallen off the back of his fishing boat while pulling in a heavy bucket of water for bathing. He was treading water when spotted by a quick thinking eclipse cruise passenger who tossed him a life jacket. The eclipse bound ship was maneuvered to extract him from the water. Singapore immigration was contacted but they refused to allow the fisherman to get off the ship for repatriation with Indonesia ― because he didn't have a passport.)

The Eclipse Redefines Cruising― Shipborne Astronomy;Science and Culture at Sea

In 1972 the Voyage to Darkness organizers ―a family of five educators ― astronomer Ted Pedas, historian Phil Sigler, and public school teachers George Pedas, Tom Pedas, and Marcy Pedas Sigler ― had bridged the academic world and the needs of a depressed shipping market to spawn a new industry ― educational theme cruises replete with shipboard lecturers and educational pursuits.
They proved wrong the Olympia's Captain's proclamation that "No one would ever attend a lecture on a cruise ship".
Launching an eclipse cruise was not smooth sailing. In the early '70s, travel agents politely demurred from promoting what they perceived as the ship of fools. "Sail North into the frigid Atlantic instead of the sunny Caribbean for two minutes of totality and risk being blinded by the eclipse?" they scoffed. Nor were the Planetariums quick to relinquish their sacrosanct eclipse to cosmic pied pipers seeking to make a buck off of God.
To compensate for the travel agent's lack of support the Pedas-Sigler entrepreneurs devised a plan enlisting the cooperation of Planetariums and Science Museums as 'Participating Agents'. The Director of the Fels Planetarium (Philadelphia) was first to see the merits of this unique revenue raising proposal. Rochester's Strasenburgh and Chicago's prestigious Adler quickly followed suit. New York's stodgy Hayden joined forces a year later in endorsing the deck of a ship as a viable alternative to terra firma in observing and photographing the eclipse.

The Pedas-Sigler pioneers of Astronomy Theme Cruises, in their quest for totality, had revamped the 'snooze-and-booze cruise' substituting lectures on sun spots, shadow bands and Bailey's Beads for bingo and deck quoits. And none too soon. "Earth people," states Ted Pedas, "are indeed fortunate to live on the only planet in the solar system where three celestial bodies, the sun, moon and earth align themselves to produce solar eclipses. In eons to come, future generations will not be provided with this solar phenomenon. Tidal forces of gravity will cause the moon to slowly spiral away from the earth."

EPILOGUE
Solar eclipse of April 6, 647 B.C.
"Zeus, father of the Olympians, made night from mid-day,
hiding the light of the shining Sun, and sore fear came upon men." ― Archilochus
The Sun God, Helios, proved much friendlier to the Pedas-Sigler modern day Hellenes (the Pedas family is of Greek descent) than to their predecessor, Icarus, who dared to sail too close to the sun.
The wrath of Olympus, when day turns into unearthly night, had been appeased. Archilochus would be pleased.
by

Ted Pedas and Marcy Pedas Sigler
(excerpts from Voyage to Darkness Pedas/Sigler eclipse cruise brochures 1972-2002)

solar eclipse highlights

Every time the solar eclipse take places, the occurrence and its observation mean a great thing for the astronomy. Recently, Professor Jay M. Pasachoff has surveyed Jinshan near Shanghai，Mogan Mountain and the reservoir of Tianhuangpin Pumped Storage Power Plant and Hangzhou City in order to choose the best location in the world to observe the astronomic spectacle, accompanied by chief scientist of National Astronomical Observatory Dr. Yan Yihua and Curator of Beijing Astronomical Observatory Dr. Zhujin.

The solar eclipse will take place on July 22, 2009 and it happens once every three hundred years. It will be a total eclipse of the sun that will only be visible from a narrow corridor through central China, including Chengdu, Chongqing, Wuhan, Suzhou, Hangzhou and Shanghai Cities, which means most parts of central China locate within the best area of observation. The solar eclipse is the longest total solar eclipse that will occur in the twenty-first century. Totality visible in Shanghai will last for up to 5 minutes. The last solar eclipse visible in Shanghai took place on May 10, 1575 during the Ming Dynasty (1368-1644) and it won’t happen again in Shanghai until June 9, 2309. There is no exaggeration to say the total solar eclipse is a rare chance once in centuries and many people are expecting its coming.

When the moon is directly between the sun and the earth, and the moon's shadow is cast upon the earth, it seems that to the people on the earth that the sun is not full and even disappearing. This is the solar eclipse. Actually this is one of the astronomical phenomenons when the sun is covered by the moon. Since the full solar eclipse belt is so narrow on earth that venues can observe this magic astronomical phenomenon is quite limited.

Now the hotel rooms are difficult to book for July 22nd 2009 in Anji Tianhuangping of Zhejiang province and Tongling in Anhui province, which were considered to be the best observation venue for the full eclipse in 2009. It is said that an isle locating on the solar eclipse belt had already been occupied by a travel agency for organizing astronomic amateurs to witness this eclipse. Those eclipse chasers are already get prepared for 2009’s eclipse. According to Shanghai Astronomical Observatory, observers’ number may create new world record next year. The full solar eclipse may influence natural environment, such as wind, temperature, animals and so on. Thus, when full solar eclipse takes place, temperature and humidity may fall sharply, wind direction may change, wind speed goes faster and it may darken suddenly during the daytime… lot of amateurs upload data and pictures from NASA to BBS to discuss the best observation venues. Since sun altitude of 2009’s eclipse is 55, residents living on high apartment in Shanghai may even witness at their home with the windows open.
After careful calculation, Prof. Jay M. Pasachoff, chairman of the Working Group on Solar Eclipse of the International Astronomical Union (IAU) finally released the information that the reservoir of Tianhuangpin Pumped Storage Power Plant, located at 119°35′east and 30°27′north and standing at 758 meters, would provide the best observing site. This information was released by after he went to Anji and made a practical survey of the place.

Transit of Phobos from Mars

A transit of Phobos across the Sun as seen from Mars takes place when Phobos passes directly between the Sun and a point on the surface of Mars, obscuring a large part of the Sun's disc for an observer on Mars. During a transit, Phobos can be seen from Mars as a large black disc rapidly moving across the face of the Sun. At the same time, the shadow of Phobos moves across the Martian surface.

The event could also be referred to as a partial occultation (or, popularly but inaccurately, a partial eclipse) of the Sun by Phobos.


Transit

A transit of Phobos from Mars usually lasts only thirty seconds or so, due to the moon's very rapid orbital period of about 7.6 hours.

Because Phobos orbits close to Mars and in line with its equator, transits of Phobos occur somewhere on Mars on most days of the Martian year. Its orbital inclination is 1.08°, so the latitude of its shadow projected onto the Martian surface shows a seasonal variation, moving from 70.4°S to 70.4°N and back again over the course of a Martian year. Phobos is so close to Mars that it is not visible south of 70.4°S or north of 70.4°N; for some days in the year, its shadow misses the surface entirely and falls north or south of Mars.

At any given geographical location on the surface of Mars, there are two intervals in a Martian year when the shadows of Phobos or Deimos is passing through its latitude. During each such interval, about half a dozen transits of Phobos can be seen by observers at that geographical location (compared to zero or one transits of Deimos). Transits of Phobos in the northern hemisphere happen during Martian autumn and winter; close to the equator they happen around the autumnal equinox and the vernal equinox; farther from the equator they happen closer to the winter solstice.

Observers at high latitudes less than 70.4° will see a noticeably smaller angular diameter for Phobos because they are considerably farther away from it than observers at Mars's equator. As a result, transits of Phobos for such observers will cover less of the Sun's disk. Because it orbits so close to Mars, Phobos cannot be seen north of 70.4°N or south of 70.4°S; such latitudes will obviously not see transits either.

Mars Rover Opportunity photographed transits of Phobos on March 7, 2004 and March 10, 2004 and March 12, 2004. In the captions below, the first row shows Earth time UTC and the second row shows Martian local solar time.

Solar eclipses on Pluto

Eclipses of the Sun on Pluto are caused when one of its three natural satellites – Charon, Nix and Hydra – passes in front of the Sun, blocking its light.

An eclipse can occur only when one of the satellites' orbital nodes, the points where their orbits cross Pluto's ecliptic, is lined up with the apparent position of the Sun as seen from Pluto. Since all three of its satellites orbit in the same plane, the times at which this is possible are the same for all three. There are only two points in Pluto's orbit where this can happen.

Charon typically presents an angular diameter of between 3 and 4 degrees of arc as seen from the surface of Pluto. The Sun appears much smaller, only 40 arcseconds to 1 arcminute. This means that during solar eclipses by Charon, a large proportion of Pluto's surface can experience a total eclipse.

There are large uncertainties in the diameters of Nix and Hydra, Pluto's two smaller moons, and as a result their apparent diameters (as seen from Pluto) are also uncertain. However, it is known that Nix's angular diameter is 3-9 minutes, while Hydra's is 2-7 minutes. These are much larger than the Sun's angular diameter, so total solar eclipses are possible with these moons.

The period when eclipses were observed on Pluto was between February 1985 and October 1990.As seen from Earth, Charon also transited Pluto every orbit during this period. By measuring the change in brightness during these transit events, astronomers were able to measure the radius of both Pluto and Charon. Nowadays, telescopes, such as the Hubble Space Telescope have high enough resolution that the radius can be measured directly.

The next period of time when solar eclipses can occur on Pluto will begin October 2103, peak in 2110, and end January 2117. During this period, solar eclipses will occur at some point on Pluto every orbit of Charon. The maximum duration of any solar eclipse by Charon as seen from Pluto during this period is about 90 minutes.

Solar eclipses on Jupiter

Solar eclipses on Jupiter occur when any of the natural satellites of Jupiter pass in front of the Sun as seen from the planet Jupiter. For bodies which appear smaller in angular diameter than the Sun, the proper term would be a transit. For bodies which are larger than the apparent size of the Sun, the proper term would be an occultation.

There are 5 satellites capable of completely occulting the Sun; Amalthea, Io, Europa, Ganymede and Callisto. All of the others are too small or too distant to be able to completely occult the Sun, so can only transit the Sun. Most of the more distant satellites also have orbits that are strongly inclined to the plane of Jupiter's orbit, and would rarely be seen to transit.

When the four largest satellites of Jupiter, the Galilean satellites, occult the Sun, a shadow transit can be seen on the surface of Jupiter which can be observed from Earth in telescopes.

Eclipses of the Sun from Jupiter are not particularly rare, since Jupiter is very large and its axial tilt (which is related to the plane of the orbits of its satellites) is relatively small - indeed, the vast majority of the orbits of all 5 of the objects capable of occulting the Sun will result in a solar occultation visible from somewhere on Jupiter's surface.

The related phenomenon of satellite eclipses in the shadow of Jupiter has been observed since the time of Giovanni Cassini and Ole Roemer in the mid Seventeenth Century. It was soon noticed that predicted times differed from observed times in a regular way, varying from up to ten minutes early to up to ten minutes late. Roemer used these errors to make the first accurate determination of the speed of light, correctly realizing the variations were caused by the varying distance between Earth and Jupiter as the two planets moved in their orbits around the Sun.

The website skytonight.comcarries links to predictions for eclipses of Jovian moons and their shadow transits.

Meteorological measurements

A marked drop of the intensity of the solar radiation occurs during solar eclipse. It influences the actions in the atmosphere. The variations of the atmospheric actions display in changes of standard meteorological and physical quantities. We can notice it by a measurement of the air temperature and other meteorological quantities (e.g.: air humidity, soil temperature, colour of the solar radiation).

The progressions of the quantities are usually detected by special weather stations because of a short duration of a total (annular) solar eclipse. The properties of the devices usually are: high speed of measurement, high resolution and sensitivity. Acquired results show very interesting variations in progressions of meteorological and physical quantities (e.g.: colour of the light).[47]

Artificial satellites

Artificial satellites can also pass in front of, or transit, the Sun as seen from Earth, but none are large enough to cause an eclipse. At the altitude of the International Space Station, for example, an object would need to be about 3.35 km across to blot the Sun out entirely. These transits are difficult to watch, because the zone of visibility is very small. The satellite passes over the face of the Sun in about a second, typically. As with a transit of a planet, it will not get dark.[44]

Artificial satellites do play an important role in documenting solar eclipses. Images of the umbra on the Earth's surface taken from Mir and the International Space Station are among the most spectacular eclipse images in history.[45] Observations of eclipses from satellites orbiting above the Earth's atmosphere are of course not subject to weather conditions.

The direct observation of a total solar eclipse from space is rather rare. The only documented case is Gemini 12 in 1966. The partial phase of the 2006 total eclipse was visible from the International Space Station. At first, it looked as though an orbit correction in the middle of March would bring the ISS in the path of totality, but this correction was postponed.[46]

Partial and annular eclipses

Viewing the Sun during partial and annular eclipses (and during total eclipses outside the brief period of totality) requires special eye protection, or indirect viewing methods. The Sun's disk can be viewed using appropriate filtration to block the harmful part of the Sun's radiation. Sunglasses are not safe, since they do not block the harmful and invisible infrared radiation which causes retinal damage. Only properly designed and certified solar filters should ever be used for direct viewing of the Sun's disk.[35] Especially, self-made filters using common objects like a floppy disk removed from its case, a Compact Disc, a black colour slide film, etc. must be avoided despite what may have been said in the media.[36]

The safest way to view the Sun's disk is by indirect projection. This can be done by projecting an image of the disk onto a white piece of paper or card using a pair of binoculars (with one of the lenses covered), a telescope, or another piece of cardboard with a small hole in it (about 1 mm diameter), often called a pinhole camera. The projected image of the Sun can then be safely viewed; this technique can be used to observe sunspots, as well as eclipses. However, care must be taken to ensure that no one looks through the projector (telescope, pinhole, etc.) directly. Viewing the Sun's disk on a video display screen (provided by a video camera or digital camera) is safe, although the camera itself may be damaged by direct exposure to the Sun. The optical viewfinders provided with some video and digital cameras are not safe.

In the partial eclipse path one will not be able to see the spectacular corona or nearly complete darkening of the sky, yet, depending on how much of the sun's disk is obscured, some darkening may be noticeable. If two-thirds or more of the sun is obscured, then an effect can be observed by which the daylight appears to be dim, as if the sky were overcast, yet objects still cast sharp shadows.

tips to watch solar eclipse

Solar eclipse watchers need to take some precautions prior to observing the eclipse. This is because the sun’s photosphere emits intense infrared and ultraviolet (UV) radiation. Just as UV radiation causes sunburn to skin, it can also damage the retinas in the eyes at a much faster rate. The human eye can suffer permanent damage if it is exposed to direct sunlight for a few seconds. It is recommended that one wears protective eyewear to safely observe an eclipse.

A safe way to view the sun is to project its image on a screen, such as white paper or cardboard. Projection works well with or without a telescope or binoculars. Other equipment that can be used to observe an eclipse are: eyepiece(s); a solar filter; a solar projection screen; a camera; a camera lens; film; a cable release (including a spare); a video camera; a videotape; spare batteries; a tripod; a tape recorder to record comments and reactions; a shortwave radio to keep track of time; a space blanket; sunscreen and a hat; a stopwatch; a thermometer; a white bed sheet used to catch a glimpse of shadow bands; duct tape; elastic bands; a logbook; and food, water and extra clothing.

Disclaimer: This article provides general information only. Information on this site is not a substitute for professional health care advice.

solar eclipse 2009

hi all,
anyone interested in astronomy and plan to visit China in 2009?

The total solar eclipse of 22nd of July 2009 will be the longest eclipse of the 21st Century being 6 minutes 38 seconds at the point of maximum eclipse in China.

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Historical eclipses

Astronomers Studying an Eclipse by Antoine Caron

Historical eclipses are a valuable resource for historians, in that they allow a few historical events to be precisely dated, from which other dates and a society's calendar can be deduced. A solar eclipse of June 15 763 BC mentioned in an Assyrian text is important for the Chronology of the Ancient Orient. Also known as the eclipse of Bur Sagale, it is the earliest solar eclipse mentioned in historical sources that has been successfully identified. Perhaps the earliest still-unproven claim is that of archaeologist Bruce Masse; on the basis of several ancient flood myths that mention a total solar eclipse, he links an eclipse that occurred May 10, 2807 BC with a possible meteor impact in the Indian Ocean.^[16] There have been other claims to date earlier eclipses, notably that of Mursili II (likely 1312 BC), in Babylonia, and also in China, during the 5th year (2084 BC) of the regime of king Zhong Kang of Xia dynasty, but these are highly disputed and rely on much supposition.^[17][18]

Herodotus wrote that Thales of Miletus predicted an eclipse which occurred during a war between the Medians and the Lydians. Soldiers on both sides put down their weapons and declared peace as a result of the eclipse. Exactly which eclipse was involved has remained uncertain, although the issue has been studied by hundreds of ancient and modern authorities. One likely candidate took place on May 28 585 BC, probably near the Halys river in the middle of modern Turkey.^[19]

An annular eclipse of the Sun occurred at Sardis on February 17 478 BC, while Xerxes was departing for his expedition against Greece, as Herodotus recorded.^[20] Hind and Chambers considered this absolute date more than a century ago.^[21] Herodotus also reports that another solar eclipse was observed in Sparta during the next year, on August 1 477 BC.^[22][23][24] The sky suddenly darkened in the middle of the day, well after the battles of Thermopylae and Salamis, after the departure of Mardonius to Thessaly at the beginning of the spring of (477 BC) and his second attack on Athens, after the return of Cleombrotus to Sparta. Note that the modern conventional dates are different by a year or two, and that these two eclipse records have been ignored so far.^[25] The Chronicle of Ireland recorded a solar eclipse on June 29, 512 AD, and a solar eclipse was reported to have taken place during the Battle of Stiklestad in the summer of 1030.

It has also been attempted to establish the exact date of Good Friday by means of solar eclipses, but this research has not yielded conclusive results.^[26] Research has manifested the inability of total solar eclipses to serve as explanations for the recorded Good Friday features of the crucifixion eclipse.^[27] (Good Friday is recorded as being at Passover, which is also recorded as being at or near the time of a full moon.)

The ancient Chinese astronomer Shi Shen (fl. 4th century BC) was aware of the relation of the moon in a solar eclipse, as he provided instructions in his writing to predict them by using the relative positions of the moon and sun.^[28] The 'radiating influence' theory for a solar eclipse (i.e., the moon's light was merely light reflected from the sun) was existent in Chinese thought from about the 6th century BC (in the Zhi Ran of Zhi Ni Zi),^[29] and opposed by the Chinese philosopher Wang Chong (27–97 AD), who made clear in his writing that this theory was nothing new.^[30] This can be said of Jing Fang's writing in the 1st century BC, which stated:

The moon and the planets are Yin; they have shape but no light. This they receive only when the sun illuminates them. The former masters regarded the sun as round like a crossbow bullet, and they thought the moon had the nature of a mirror. Some of them recognized the moon as a ball too. Those parts of the moon which the sun illuminates look bright, those parts which it does not, remain dark.^[29]

The ancient Greeks had known this as well, since it was Parmenides of Elea around 475 BC who supported the theory of the moon shining because of reflected light, and was accepted in the time of Aristotle as well.^[29] The Chinese astronomer and inventor Zhang Heng (78–139 AD) wrote of both solar and lunar eclipses in the publication of Ling Xian in 120 AD, supporting the radiating influence theory that Wang Chong had opposed (Wade-Giles):

The sun is like fire and the moon like water. The fire gives out light and the water reflects it. Thus the moon's brightness is produced from the radiance of the sun, and the moon's darkness (pho) is due to (the light of) the sun being obstructed (pi). The side which faces the sun is fully lit, and the side which is away from it is dark. The planets (as well as the moon) have the nature of water and reflect light. The light pouring forth from the sun (tang jih chih chhung kuang) does not always reach the moon owing to the obstruction (pi) of the earth itself—this is called 'an-hsü', a lunar eclipse. When (a similar effect) happens with a planet (we call it) an occulation (hsing wei); when the moon passes across (kuo)(the sun's path) then there is a solar eclipse (shih).^[31]

The later Chinese scientist and statesman Shen Kuo (1031–1035 AD) also wrote of eclipses, and his reasoning for why the celestial bodies were round and spherical instead of flat (Wade-Giles spelling):

The Director [of the Astronomical Observatory] asked me about the shapes of the sun and moon; whether they were like balls or (flat) fans. If they were like balls they would surely obstruct (ai) each other when they met. I replied that these celestial bodies were certainly like balls. How do we know this? By the waxing and waning (ying khuei) of the moon. The moon itself gives forth no light, but is like a ball of silver; the light is the light of the sun (reflected). When the brightness is first seen, the sun(-light passes almost) alongside, so the side only is illuminated and looks like a crescent. When the sun gradually gets further away, the light shines slanting, and the moon is full, round like a bullet. If half of a sphere is covered with (white) powder and looked at from the side, the covered part will look like a crescent; if looked at from the front, it will appear round. Thus we know that the celestial bodies are spherical...Since the sun and moon are in conjunction (ho) and in opposition (tui) once a day, why then do they have eclipses only occasionally?' I answered that the ecliptic and the moon's path are like two rings, lying one over the other (hsiang tieh), but distant by a small amount. (If this obliquity did not exist), the sun would be eclipsed whenever the two bodies were in conjunction, and the moon would be eclipsed whenever they were exactly in position. But (in fact) though they may occupy the same degree, the two paths are not (always) near (each other), and so naturally the bodies do not (intrude) upon one another.^[32]

Final totality

Spectacular solar eclipses are an extreme rarity within the universe at large. They are seen on Earth because of a fortuitous combination of circumstances that are statistically very improbable. Even on Earth, spectacular eclipses of the type familiar to people today are a temporary (on a geological time scale) phenomenon. Many millions of years in the past, the Moon was too close to the Earth to precisely occult the Sun as it does during eclipses today; and many millions of years in the future, it will be too far away to do so.

Due to tidal acceleration, the orbit of the Moon around the Earth becomes approximately 3.8 cm more distant each year. It is estimated that in 600 million years, the distance from the Earth to the Moon will have increased by 23,500 km, meaning that it will no longer be able to completely cover the Sun's disk. This will be true even when the Moon is at perigee, and the Earth at aphelion.

A complicating factor is that the Sun will increase in size over this timescale. This makes it even more unlikely that the Moon will be able to cause a total eclipse. We can therefore say that the last total solar eclipse on Earth will occur in slightly less than 600 million years.^[15]

Occurrence and cycles

Total Solar Eclipse Paths: 1001–2000. This image was merged from 50 separate images from NASA.^[11]

Total solar eclipses are rare events. Although they occur somewhere on Earth every 18 months on average,^[12] it has been estimated that they recur at any given place only once every 370 years, on average. The total eclipse only lasts for a few minutes at that location, as the Moon's umbra moves eastward at over 1700 km/h. Totality can never last more than 7 min 31 s, and is usually much shorter: during each millennium there are typically fewer than 10 total solar eclipses exceeding 7 minutes. The last time this happened was June 30, 1973 (7 min 3 sec). Observers aboard a Concorde aircraft were able to stretch totality to about 74 minutes by flying along the path of the Moon's umbra. The next eclipse exceeding seven minutes in duration will not occur until June 25, 2150. The longest total solar eclipse during the 8,000-year period from 3000 BC to 5000 AD will occur on July 16, 2186, when totality will last 7 min 29 s.^[13] For comparison, the longest eclipse of the 21st century will occur on July 22, 2009 and last 6 min 39 sec.

If the date and time of any solar eclipse are known, it is possible to predict other eclipses using eclipse cycles. Two such cycles are the Saros and the Inex. The Saros cycle is probably the best known, and one of the most accurate, eclipse cycles. The Inex cycle is itself a poor cycle, but it is very convenient in the classification of eclipse cycles. After a Saros cycle finishes, a new Saros cycle begins one Inex later, hence its name: in-ex. A Saros cycle lasts 6,585.3 days (a little over 18 years), which means that after this period a practically identical eclipse will occur. The most notable difference will be a shift of 120° in longitude (due to the 0.3 days) and a little in latitude. A Saros series always starts with a partial eclipse near one of Earth's polar regions, then shifts over the globe through a series of annular or total eclipses, and ends at the opposite polar region. A Saros (series) lasts 1226 to 1550 years and 69 to 87 eclipses, with about 40 to 60 central.^[14]

Geometry

Diagram of solar eclipse (not to scale).

The diagram to the right shows the alignment of the Sun, Moon and Earth during a solar eclipse. The dark gray region below the Moon is the umbra, where the Sun is completely obscured by the Moon. The small area where the umbra touches the Earth's surface is where a total eclipse can be seen. The larger light gray area is the penumbra, in which only a partial eclipse can be seen.

The Moon's orbit around the Earth is inclined at an angle of just over 5 degrees to the plane of the Earth's orbit around the Sun (the ecliptic). Because of this, at the time of a new moon, the Moon will usually pass above or below the Sun. A solar eclipse can occur only when the new moon occurs close to one of the points (known as nodes) where the Moon's orbit crosses the ecliptic.

As noted above, the Moon's orbit is also elliptical. The Moon's distance from the Earth can vary by about 6% from its average value. Therefore, the Moon's apparent size varies with its distance from the Earth, and it is this effect that leads to the difference between total and annular eclipses. The distance of the Earth from the Sun also varies during the year, but this is a smaller effect. On average, the Moon appears to be slightly smaller than the Sun, so the majority (about 60%) of central eclipses are annular. It is only when the Moon is closer to the Earth than average (near its perigee) that a total eclipse occurs.^[6][7]

The Moon orbits the Earth in approximately 27.3 days, relative to a fixed frame of reference. This is known as the sidereal month. However, during one sidereal month, the Earth has revolved part way around the Sun, making the average time between one new moon and the next longer than the sidereal month: it is approximately 29.5 days. This is known as the synodic month, and corresponds to what is commonly called the lunar month.

A Total eclipse in the umbra.
B Annular eclipse in the antumbra.
C Partial eclipse in the penumbra

The Moon crosses from south to north of the ecliptic at its ascending node, and vice versa at its descending node. However, the nodes of the Moon's orbit are gradually moving in a retrograde motion, due to the action of the Sun's gravity on the Moon's motion, and they make a complete circuit every 18.6 years. This means that the time between each passage of the Moon through the ascending node is slightly shorter than the sidereal month. This period is called the draconic month.

Finally, the Moon's perigee is moving forwards in its orbit, and makes a complete circuit in about 9 years. The time between one perigee and the next is known as the anomalistic month.

The Moon's orbit intersects with the ecliptic at the two nodes that are 180 degrees apart. Therefore, the new moon occurs close to the nodes at two periods of the year approximately six months apart, and there will always be at least one solar eclipse during these periods. Sometimes the new moon occurs close enough to a node during two consecutive months. This means that in any given year, there will always be at least two solar eclipses, and there can be as many as five. However, some are visible only as partial eclipses, because the umbra passes above Earth's north or south pole, and others are central only in remote regions of the Arctic or Antarctic.^[8][9]

Terminology

Central eclipse is often used as a generic term for a total, annular, or hybrid eclipse. This is, however, not completely correct: the definition of a central eclipse is an eclipse during which the central line of the umbra touches the Earth's surface. It is possible, though extremely rare, that part of the umbra intersects with Earth (thus creating an annular or total eclipse), but not its central line. This is then called a non-central total or annular eclipse.^[5]

The term solar eclipse itself is strictly speaking a misnomer. The phenomenon of the Moon passing in front of the Sun is not an eclipse, but an occultation. Properly speaking, an eclipse occurs when one object passes into the shadow cast by another object. For example, when the Moon disappears at full moon by passing into Earth's shadow, the event is properly called a lunar eclipse. Therefore, technically, a solar eclipse actually amounts to an eclipse of the Earth.

four types of solar eclipses

Annular eclipse.

There are four types of solar eclipses:

• A total eclipse occurs when the Sun is completely obscured by the Moon. The intensely bright disk of the Sun is replaced by the dark silhouette of the Moon, and the much fainter corona is visible. During any one eclipse, totality is visible only from at most a narrow track on the surface of the Earth.
• An annular eclipse occurs when the Sun and Moon are exactly in line, but the apparent size of the Moon is smaller than that of the Sun. Hence the Sun appears as a very bright ring, or annulus, surrounding the outline of the Moon.
• A hybrid eclipse is intermediate between a total and annular eclipse. At some points on the surface of the Earth it is visible as a total eclipse, whereas at others it is annular. Hybrid eclipses are rather rare.
• A partial eclipse occurs when the Sun and Moon are not exactly in line, and the Moon only partially obscures the Sun. This phenomenon can usually be seen from a large part of the Earth outside of the track of an annular or total eclipse. However, some eclipses can only be seen as a partial eclipse, because the umbra never intersects the Earth's surface.

The match between the apparent sizes of the Sun and Moon during a total eclipse is a coincidence. The Sun's distance from the Earth is about 400 times the Moon's distance, and the Sun's diameter is about 400 times the Moon's diameter. Because these ratios are approximately the same, the sizes of the Sun and the Moon as seen from Earth appear to be approximately the same: about 0.5 degree of arc in angular measure.

Because the Moon's orbit around the Earth is an ellipse, as is the Earth's orbit around the Sun, the apparent sizes of the Sun and Moon vary.^[1][2] The magnitude of an eclipse is the ratio of the apparent size of the Moon to the apparent size of the Sun during an eclipse. An eclipse when the Moon is near its closest distance from the Earth (i.e., near its perigee) can be a total eclipse because the Moon will appear to be large enough to cover completely the Sun's bright disk, or photosphere; a total eclipse has a magnitude greater than 1. Conversely, an eclipse when the Moon is near its farthest distance from the Earth (i.e., near its apogee) can only be an annular eclipse because the Moon will appear to be slightly smaller than the Sun; the magnitude of an annular eclipse is less than 1. Slightly more solar eclipses are annular than total because, on average, the Moon lies too far from Earth to cover the Sun completely. A hybrid eclipse occurs when the magnitude of an eclipse is very close to 1: the eclipse will appear to be total at some locations on Earth and annular at other locations.^[3]

The Earth's orbit around the Sun is also elliptical, so the Earth's distance from the Sun varies throughout the year. This also affects the apparent sizes of the Sun and Moon, but not so much as the Moon's varying distance from the Earth. When the Earth approaches its farthest distance from the Sun (the aphelion) in July, this tends to favor a total eclipse. As the Earth approaches its closest distance from the Sun (the perihelion) in January, this tends to favor an annular eclipse.

Solar eclipse

This article is about the astronomical phenomenon. For the video game, see Solar Eclipse (video game).

A solar eclipse occurs when the Moon passes between the Sun and the Earth so that the Sun is wholly or partially obscured. This can only happen during a new moon, when the Sun and Moon are in conjunction as seen from the Earth. At least two and up to five solar eclipses occur each year on Earth, with between zero and two of them being total eclipses.^{[citation needed]} Total solar eclipses are nevertheless rare at any location because during each eclipse totality exists only along a narrow corridor in the relatively tiny area of the Moon's umbra.

A total solar eclipse is a spectacular natural phenomenon and many people travel to remote locations to observe one. The 1999 total eclipse in Europe helped to increase public awareness of the phenomenon, as illustrated by the number of journeys made specifically to witness the 2005 annular eclipse and the 2006 total eclipse. The most recent solar eclipse occurred on August 1, 2008, and was a total eclipse.

In ancient times, and in some cultures today, solar eclipses have been attributed to supernatural causes. Total solar eclipses can be frightening for people who are unaware of their astronomical explanation, as the Sun seems to disappear in the middle of the day and the sky darkens in a matter of minutes.

Geometry of a Total Solar Eclipse (not to scale).

Photo of 1999 total eclipse.