Total eclipse — longest of the century
On 22 July 2009 the longest total solar eclipse of the 21st century crossed India and China and swept out over the Pacific. Totality lasted up to 6 minutes 39 seconds, a length not beaten until 2132.
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The story
On 22 July 2009 the Moon's shadow touched down on the west coast of India. It crossed northern India, Nepal, Bangladesh, Bhutan and Myanmar, then ran straight across the middle of China. After brushing the islands south of Japan it headed out over the Pacific. This was the longest total solar eclipse of the 21st century.
The longest totality happened over the ocean south of Japan's Ogasawara (Bonin) Islands. There the Sun was completely hidden for up to 6 minutes 39 seconds. A typical total eclipse lasts two or three minutes, so this was more than twice as long. The record will stand until the eclipse of 13 June 2132, which will last 6 minutes 55 seconds.
The path of the shadow passed through large cities such as Chengdu, Wuhan, Hangzhou and Shanghai. That meant a very large number of people lived under the path of totality. The weather, though, did not help everyone. Shanghai was covered by heavy cloud, so people there could not see the Sun and only felt the sudden darkness in the middle of the morning.
At Varanasi, the holy city on the Ganges in India, the eclipse happened shortly after sunrise, and huge crowds gathered by the river to meet it. In Japan, observers travelled to the small island of Akusekijima, the inhabited place closest to the point of longest totality, where the eclipse would last 6 minutes 26 seconds, but the weather there was poor as well.
Viewing guide — where, when, how
Choose the 2009 eclipse in the sky view's event list to replay totality over Shanghai at about half past nine in the morning, local time, on 22 July, without the clouds. At that moment the Sun stood fairly high in the south-eastern sky. Move the location to Chengdu or Wuhan and totality begins a little earlier, because the shadow travelled from west to east.
The orbit view's event replay shows the Moon, near its closest point to Earth, sliding between the Sun and Earth. Turn on the lunar orbit to see that the Earth–Moon distance at that moment was shorter than average. The scene makes the reason for the long totality easy to see.
Eclipses from the same family, Saros 136, can be compared too. The one before was the eclipse of 11 July 1991 over Hawaii and Mexico, lasting 6 minutes 53 seconds. The next is the eclipse of 2 August 2027 over Luxor in Egypt, lasting 6 minutes 23 seconds. Calling up all three in the sky view shows the shadow's path shifting a little each time.
See this for yourself — open that sky at that moment · replay the moment in the orbit view
Why this eclipse is special
The eclipse was long because of distances. The Moon travels around Earth on an oval path, so it is sometimes nearer and sometimes farther. On this day the Moon was close to its nearest point, so it looked large in the sky. Earth, meanwhile, is farthest from the Sun in early July, so the Sun looked a little smaller. A large Moon covering a small Sun with room to spare made totality long.
One more condition helps. The shadow needs to pass near the middle of Earth's face, fairly close to the equator. There, Earth's spin carries the ground along in the same direction as the shadow, so the shadow seems to linger over each place a little longer. All of these conditions rarely come together, and even in theory totality cannot last much more than about 7 minutes 32 seconds.
Long totality is valuable for scientists as well. Only during totality can the corona, the faint light around the Sun, be studied in detail with the naked eye and ground-based telescopes. The longer it lasts, the more time there is to record slow changes in the corona. In 2009 the Sun was in a very quiet period with few sunspots, and the corona showed the simple shape typical of such times.
Background and earlier eclipses
Eclipses repeat in a similar pattern about every 18 years and 11 days, and a chain of such related eclipses is called a Saros series. The 2009 eclipse belongs to Saros 136. This series has produced unusually long eclipses in the 20th and 21st centuries. Its eclipse of 20 June 1955 over the Philippines lasted 7 minutes 8 seconds, the longest in the series.
Since then the eclipses of this series have been getting slowly shorter. The 1973 eclipse over Africa lasted 7 minutes 4 seconds, the 1991 eclipse over Hawaii and Mexico 6 minutes 53 seconds, and 2009 6 minutes 39 seconds. The 2027 Luxor eclipse is expected to last 6 minutes 23 seconds. The change comes from small shifts, every 18 years, in the distances between Sun, Moon and Earth.
On Japan's main islands the eclipse was only partial, with part of the Sun covered. In Tokyo about 70 percent of the Sun's width was hidden. To see totality, people had to go to small islands in the south or out to sea on ships. The land closest to the point of longest totality was the Iwo Jima (Volcano) Islands.
At the time of the eclipse the Sun was at the weakest point of its roughly 11-year cycle of activity. This quiet period in 2008 and 2009 had a great many days without a single sunspot and is counted as the deepest minimum in about a hundred years. At such times the corona looks simple, with a few long streamers stretching out along the Sun's equator.
FAQ
How long was totality?
Up to 6 minutes 39 seconds, the longest of the 21st century. It will not be beaten until the eclipse of 13 June 2132, which lasts 6 minutes 55 seconds.
Why was it so long?
The Moon was near Earth and looked large, while Earth was far from the Sun and the Sun looked small. The large Moon covered the small Sun with room to spare.
Could it be seen from Shanghai?
Shanghai was under heavy cloud, so the Sun could not be seen; people only felt the sudden darkness.
When is the next eclipse of the same series?
The total eclipse of 2 August 2027 over Luxor in Egypt, lasting up to 6 minutes 23 seconds.
Related
- Total solar eclipse of August 2027
- The Great American Eclipse (2017)
- Total solar eclipse of September 2035
- The Sun — object index
- The Moon — object index
Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.