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"Total Eclipses" is the title of a DOS-disc based program which enables the viewing of Solar Eclipses by the Moon as if from the Earth. Inputting of dates leads to historical and future eclipses and Earth latitude and longitude permits views from different places on this planet.
The disc is available from its author, Peter Duffett-Smith, at a price understood to be £15. Initial contact with the author needs to be by email; the most recent address we have for him is "pjds@mrao.cam.ac.uk".
The instructions for use of the program are of course supplied..
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There are three types of shadow created in a Solar Eclipse (see diagram)
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There are seven different types of solar eclipse (see the two diagrams):
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There are four different contacts during Annular and Total Eclipses.
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St.Mark's gospel chapter 15 verse 33: "And when the sixth hour was come, there was darkness over the whole land until the ninth hour". This of course related to the crucifixion of Jesus. I believe that Mark was referring to a solar eclipse. Total Eclipse has been run for every year since Year 1 (there was no Year 0). The only possible date this could have been was 24 November 29. If I am right, this would alter Easter somewhat. Entering longitude 35°15"E and latitude 31°47"N, the computer comes up with a magnitude of 95·4% which would be large enough to cause "the darkness" in St. Mark's gospel. Latitude 35°N gives a reading of 100·8% in other words total. Historians give the probable birth of Jesus between 4 and 7 years BC. This would make Jesus aged between 32 and 35 when he was crucified at Jerusalem!
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The most celebrated eclipse ever recorded in England occurred on 3 May 1715. It made a rare passing directly over London, with many famous people recording the experience. It also passed over Devon, with another total eclipse being visible there again on 22 May 1724. This confirmed that solar eclipses can occur very roughly every 400 years in the same place. However, they can also happen twice in nine years with no more for 800 years!
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The most recent total eclipse occurred on 11 August 1999. My wife and I went to Cornwall for this rare event I had been looking forward to for 60 years. The experience alone was daunting: 70°F to zero in two seconds flat. However, some 30,000 feet of cloud cover stopped any chance of filming it. Guess what? The day before and the next one were both clear blue skies! It did go jet black on the day though; even the seagulls were scared stiff!
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Allowance should be made for the change from Julian to Gregorian calendar 5/15 October 1582. In Britain it was not changed until nearly 200 years later: 2/14 September 1752. People thought that they had lost 11 days!
Earth, Moon & Sun are in similar configuration after 223 lunations. So 223 lunations of average 29·5306 days x 223 = 6585·3238 days. This is 18 years plus 10·32 or 11·32 days, depending on leap years. This phenomenon is called a Saros Cycle, when eclipses recur again. A German Theodor von Oppolzer listed 8,000 solar eclipses between 1208 BC and AD 2161. He numbered the Saros Cycles in which the eclipses appeared from 1 to 160. Although they appear to average 50 each, this is wrong because, for instance, Saros 136 contained no less than 71 eclipses from AD 1360 to AD 2622. There are between 70 and 85 eclipses in a Saros, lasting from 1,200 and 1,500 years. There are in excess of 80 Saros series running at any one time. The number of the eclipse within a Saros series is called a Relno. 0 is the middle of the series at the equator, with 1 following and -1 preceding it, etc. Saros series that start with positive Gamma start near North Pole and negative Gamma start from South Pole. Saros series start with Partial eclipses, then annular followed by total as they approach the equator. This process reverses as they cross the equator. Each successive one moves roughly 120° westward and about 2° variation in latitude.
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Distance by which shadow axis of Moon misses centre of the Earth. Gamma = 0 means the Moon's shadow axis passes directly through the centre of the Earth. A positive Gamma means that it passes north of the equator. A negative Gamma means that it passes south of the equator. See how it affects the Saros Cycles above.
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With a polar radius of 3,950 miles, each degree of latitude averages just under 69 miles. Total Eclipse is tolerant in finding the tracking if input is within 10% of accuracy. North of equator is entered as plus and South of equator is entered as minus.
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At the equator with a circumference of 24,902 miles, each degree of longitude averages 24,902 divided by 360 = just over 69 miles. Like latitude, Total Eclipse is tolerant provided that the accuracy of input is within 10%. I bought both a CD and a World Reference Atlas from Dorling Kindersley. To my horror I found many of their grid references were inaccurate. This caused both peculiar results and also took much of my time putting their errors right. After two years hard pressure on DK they finally admitted their mistakes and gave me two references as compensation: both corrected to my error listings. In Indonesia all the lines of longitude were 10 degrees out! So I had no chance at all in obtaining accurate tracking over that country.
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Total eclipses have a magnitude of from 100·0% to 103·5%. Annular eclipses have a magnitude of 95·0% to 99·9%. Partial eclipses have a magnitude of below 95%.
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There are approximately 227 eclipses per century world-wide:-
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In Astronomy: two co-ordinates describing the position of an object above the Earth.
Altitude is expressed as angular elevation up to 90° above the horizon.
Azimuth, in astronomical measurement, is quoted as the number of degrees clockwise from due South.
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Seconds before totality, the last sliver of the crescent Sun fragments into individual beads of light known as "Baily's Beads". Named after English astronomer Francis Baily, who described the annular eclipse in Scotland 15 May 1836 as seeing: "a string of bright beads".
Lunar Limb Profile varies the appearance of "Baily's Beads" because from Earth, due to libration, we can only see 59% of the Moon's surface.
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Conjunction is the position of the Moon or planets, when they are in line with the Sun as seen from Earth.
Occultation is when a celestial body temporarily disappears, as it moves out of sight brhind another body in the Solar System.
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Ecliptic is the circle on the celestial sphere representing the apparent annual path of the Sun relative to the stars. It is inclined at 23°45" to the celestial equator.
Nodes are where the Moon's orbit tilted at 5° to the ecliptic plane crosses the Earth's orbit at two places. An eclipse can occur only when the Sun is near to one of the nodes as the Moon crosses its ecliptic path.
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Central Line is the line where maximum duration of the solar eclipse can be visible on the Earth. The maximum duration (at the equator) can be 7½ minutes total and 12½ minures annular. Path width can be rarely as hugh as 400 miles. The solar eclipse on the 11 August 1999 tracked from Newfoundland across the Atlantic to Cornwall, France, Germany, Romania, Greece, Turkey, Iraq, Iran, Pakistan and India.
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Eclipses below the horizon before dawn or after sunset obviously are unable to be seen. "Double Dawn" eclipse is where dawn has broken and a eclipse happens minutes later. 31 May 2003 should be similar.
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Mylar filters allow for personal viewing, by cutting out the harmful infra-red radiation. Eyes will be permanently damaged if the Sun is looked at with the naked eye. I know somebody who did just that.
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Solar surface that one normally sees and which is completely covered during totality. The Sun's photosphere rotates differentially, ie more rapidly at the equator than at the poles.
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Same as Greenwich Time based on Earth's rotation which is slowing down. Its rotation can only be calculated by observation over a long period mainly using old Chinese listings.
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