[Total Solar Eclipse: 2012]
The 2009 Eclipse:
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The Total Solar Eclipse of 22 July 2009.
The narrow blue region is the path of totality (also known as the umbra).
The Moon's umbra (shadow) travels from west to east (left to right and top to bottom on the map). At the point of greatest eclipse, totality is at local midday. The duration of totality at greatest eclipse is 6 minutes 39 seconds, making this the longest total solar eclipse of the 21st century. This occured in the Pacific Ocean. On either side of that point, the duration of totality is less. To the West of greatest eclipse the eclipse was total before local noon; East of it, totality was seen after local noon. The umbra is generally widest around the time of greatest eclipse as the Earth is bulging out towards the Moon in that region. This brings the Earth's surface closer to the Moon.
The area on either side of the path of totality (in pale blue) is called the penumbra and provided a partial eclipse, the magnitude decreasing with distance from the path of totality. Beyond the partial region no eclipse is visible.
The sub-solar point is the location where the Sun is overhead at the time of greatest eclipse; in July this point is North of the equator. The parts in red on either end of the umbra are the regions where the eclipse occurs during sunrise (left) or sunset (right).
The path of totality began off the Western coast of India (at sunrise) and passed over northern India. It clipped parts of (Bhutan) and Burma before entering China where it followed the Yangtze River covering several large cities like Chengdu, Chongqing, Wuhan, Hangzhou, Suzhou and Shanghai.
After leaving China the path crossed a few islands in Japan and then headed across the Pacific Ocean where it reached greatest eclipse. The path left the Earth in the South Pacific (at sunset).
The umbra took 3 hours 25 minutes to traverse its entire path of 15,150km, covering 0.71% of the Earth's surface.
The path of totality is the pair of red lines moving across China from bottom left to upper right. The centre line runs between the two red lines.
It takes about 40 minutes for the umbra to cross this region.
The red lines crossing the path are the positions of the umbra at ten minute intervals (all in Universal Time which is essentially GMT). For each position, the accompanying boxes contain the time of mid-eclipse, the duration of totality, and the altitude of the Sun.
The duration of totality at Shanghai (the largest city in the area) is about 5 minutes (depending on which part of this large city you are located in). The duration of totality on the centre line south of Shanghai was 5 minutes 55 seconds. Our eclipse site was about ten kilometres from this point at Jinshanwei. The duration here was 5m 54s.
The Moon's shadow took about ten minutes to cross this region.
|Location||Jinshan Beach - Shanghai, China|
|Latitude||30° 42' 46" N|
|Longitude||121° 20' 54" E|
|Distance from Centre Line||less than 10 km|
|1st Contact (UT + 8)||08:23|
|Duration of Totality||5m 54s|
|Path Width||249 km|
|Major Axis||297 km|
|Minor Axis||249 km|
|Direction of Shadow Approach||265°|
|Umbral Velocity||0.831 km/s|
|Position Angle: 2nd Contact||109°|
|Position Angle: 3rd Contact||289°|
|Saros Details||136 (37 / 71)|
The Location, Latitude, Longitude and Altitude (in metres) are for the observation site at Jinshan, a beach approximately 70km south of the city of Shanghai in China. The figures were measured on a Garmin GPS 12 Personal Navigator.
The Distance from Centre Line was estimated from Google Interactive maps provided by Fred Espenak.
First Contact is the beginning of the eclipse when the first "bite" appears on the Sun's disk; it is the beginning of the partial phase. Second Contact is the beginning of totality. Third Contact is the end of totality. Fourth Contact is the end of the partial eclipse. The times are in local time which, for this eclipse, is UT + 8 (GMT plus eight hours).
The Duration of the eclipse at the observation site was 5 minutes 54 seconds.
The Path Width is the width of the path of totality. The umbra itself was slightly elliptical in shape. The Major Axis is the longest axis of the umbra; the Minor Axis is the shorter axis. The umbra at the observation site was 297km long and 249km wide and produced a path width of 249km. The path width was wide enough to make the eclipse very dark.
The Direction of the Shadow indicates that the umbra approached the observation site from the West. The Umbral Velocity is the speed of the Moon's shadow (831 metres per second) at the observation site. This and the umbral width determine the duration of the total eclipse.
The Sun's Altitude is measured from the horizon; the Azimuth is the direction of the Sun measured clockwise from North. The figures are for mid-eclipse. The Position Angles indicate the exact position of the Sun's disk where the Moon covers and uncovers the Sun at the beginning and end of totality (not useful for a clouded out eclipse).
The Saros is a collection of eclipses belonging to a series. Each member of the series is followed by a similar eclipse approximately 18 years, 11 days and 8 hours later. This eclipse is a member of Saros number 136. It is the 37th eclipse out of a total of 71 in the series.
The series began on 14 June 1360 with a small partial eclipse in the Antarctic regions. This was followed by 7 partial eclispes of increasing magnitude as the Moon's shadow moved closer to the Earth's centre with each successive eclipse. On 8 September 1504, the Moon's shadow finally made contact with the Earth but the Moon was too far to cover the Sun completely and an annular eclipse of 0m 32s duration occurred. The series consisted of 5 more annular eclipses of decreasing duration as the Moon approached the Earth. On 22 November 1612, the eclipses became hybrid, that is annular along some of the path and total along other parts. There were six of these.
The first completely total eclipse of the series occurred on 27 January 1721 (the 21st eclipse, duration 1m 07s). Saros 136 has 44 total eclipses and after the first, the duration slowly increased as the Moon continued to approach the Earth. The 32nd eclipse (29 May 1919) is famous as the eclipse observed by Arthur Eddington to verify Albert Einsten's Theory of Relativity. This eclipse is so famous that the BBC made a drama documentary about it starring an actor who plays Dr Who (a UK science fiction character).
The following three eclipses of this series were all over 7 minutes long: 8 June 1937 (7m 04s), 20 June 1955 (7m 08s) and 30 June 1973 (7m 04s). These three were the longest eclipses of the 20th century and, indeed, the only 7 minutes eclipses of the 20th century. They were the first eclispes over 7 minutes long since 1062. There will not be another eclipse of 7 minutes until 2132.
Kryss and Talaat saw the previous eclipse of this Saros in Mexico.
The duration of totality is now decreasing. The final total eclipse of Saros 136 (the 64th of the series) will occur on 13 May 2496 (duration 1m 02s). The series ends with seven partial eclipses, the final one being a small partial (10%) in the Artcic on 30 July 2622. The entire series will last for 1262 years.
Gamma determines how the Moon's shadow, if extended, would pass through the Earth. A Gamma of zero implies that the shadow would pass through the exact centre of the Earth. A Gamma of greater than 1 misses the Earth and no total eclipse would occur. A positive Gamma passes North of the Earth's centre; a negative Gamma passes South of the Earth's centre. The value of Gamma for this eclipse is 0.0696. This means that the shadow passes just North of the Earth's centre, about a 7% of the way to the edge of the Earth. This, combined with the fact that in late July, the Northern Hemisphere is tilted towards the Sun, produces an eclipse mainly in the Northern tropical regions.
The small value of Gamma added to a July eclipse (when the Sun is at its furthest from the Earth) added to the Moon being at its closest to the Earth just four hours before the beginning of the eclipse, leads to a relatively long totality.
The Diameter Ratio determines how much bigger the Moon's apparent radius is than the Sun's. In this case, the Moon's radius is 1.0769 that of the Sun's. A total eclipse can only occur if this figure is greater than 1. The Moon would then appear larger than the Sun and could cover it completely. If this figure was less than one a total eclipse could not occur because the Moon would appear smaller than the Sun. The Obscuration determines how much larger the Moon's apparent area is than the Sun's.