Annular eclipse — Maldives, longest of the millennium (2010)
On 15 January 2010 the ring of fire lasted 11 minutes 8 seconds, the longest annular eclipse between 2001 and 3000. Its path ran from Africa across the Indian Ocean, the Maldives and southern India to China.
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The story
On 15 January 2010 an annular eclipse took place: the Moon covered the middle of the Sun and left only its edge showing, like a ring. Where the ring lasted longest, it stayed for 11 minutes 8 seconds. That makes it the longest annular eclipse of the thousand years from 2001 to 3000. A longer ring will not appear again until the year 3043.
The reason for this long ring lies in distance. The Moon travels around Earth on an oval path, so it is sometimes farther away and sometimes closer. On this day the Moon was near its farthest point and looked a little smaller than usual. At the same time Earth is closest to the Sun in early January, so the Sun looked a little larger. A small Moon crossing a large Sun takes a long time to pass the middle.
The Moon's shadow began its journey in the Central African Republic. It crossed the Democratic Republic of the Congo, Uganda and Kenya, went out over the Indian Ocean, passed the Maldives, and then crossed southern India, Sri Lanka and Myanmar before ending at sunset in China. At its widest the band where the ring could be seen was 333 km across, which is very wide for an annular eclipse.
In Malé, the capital of the Maldives, the ring lasted 10 minutes 45 seconds around midday. The Moon covered about 92% of the Sun's width, but only about 84% of its area. The light that remained was still strong, so the sky did not turn dark like night; it only dimmed, much like a cloudy day. The orbit view reproduces the small, distant Moon sliding slowly across the face of the Sun.
Viewing guide — where, when, how
The band where the ring could be seen ran from central Africa to the Maldives, across Kerala and Tamil Nadu in southern India, over northern Sri Lanka and Myanmar, and into China. In India the ring was visible for about ten minutes along a line from Thiruvananthapuram at the southern tip to Rameswaram. Outside that band, most of East Africa, the Middle East, South Asia and South-East Asia saw a partial eclipse, with only part of the Sun covered.
An annular eclipse must never be watched with bare eyes, at any moment. The ring left around the Moon is ordinary sunlight straight from the Sun's surface, and even a short look can hurt the eyes. In a total eclipse filters may come off during the brief minutes when the Sun is completely hidden, but an annular eclipse has no such moment. Certified eclipse glasses must stay on from start to finish, and telescopes or cameras need a solar filter fitted over the front.
The sky view follows the Sun over Malé and slows down as the ring closes, reproducing that midday scene. If the viewing place is changed to Kerala or Sri Lanka, the scene is recalculated with that place's clock time and the Sun's height there. This makes it easy to compare how the same eclipse looked from different spots.
See this for yourself — open that sky at that moment · replay the moment in the orbit view
Why this eclipse is special
How long an annular eclipse lasts depends on how large the Moon and the Sun look in the sky. The farther the Moon, the smaller it looks; the closer the Sun, the larger it looks. In January 2010 both conditions came together. As a result, the eclipse let anyone see with their own eyes that the Moon's path around Earth is not a perfect circle.
During an annular eclipse the corona, the Sun's faint outer atmosphere, cannot be seen. Instead, just as the ring closes and opens, sunlight shines through the valleys between mountains on the Moon's edge and breaks into bright dots. These are called Baily's beads. By timing the beads and measuring their pattern, scientists can work out the shape of the Moon's edge and the size of the Sun very precisely.
Because the path crossed crowded southern India and Sri Lanka, a very large number of people saw the eclipse. The Vikram Sarabhai Space Centre in Thiruvananthapuram studied how the upper air and the ionosphere changed during the eclipse. The ionosphere is a layer of air that becomes electrically charged when sunlight strikes it, so a sudden loss of sunlight is a natural experiment on how that layer responds.
Background and earlier eclipses
Eclipses repeat in a similar form about every 18 years and 11 days. Each chain of repeating eclipses is called a Saros series. The 2010 eclipse belongs to Saros 141. The previous member of the series happened over the Pacific on 4 January 1992, and the next is the annular eclipse of 26 January 2028, which crosses South America, Spain and Portugal. The ring in this series is getting a little shorter with each return.
Annular eclipses longer than eleven minutes are very rare. The next one with a longer ring is calculated for 23 December 3043. Total eclipses, in contrast, cannot last much more than about seven and a half minutes. A total eclipse needs the Moon to look large, while an annular one needs it to look small, so the conditions that make each kind long are exact opposites.
Six months later, on 11 July 2010, a total eclipse crossed the South Pacific and hid the Sun completely for 5 minutes 20 seconds. That is why 2010 is remembered as a year with a record annular eclipse and a fairly long total eclipse only half a year apart. Both paths also spent most of their length over the sea.
FAQ
Why was this annular eclipse so long?
The Moon was near its farthest point from Earth and looked small, while Earth had just passed its closest point to the Sun, so the Sun looked large. A small Moon takes a long time to cross a large Sun, so the ring lasted a long time.
Did the sky go dark?
No. About 84% of the Sun's area was covered, but the remaining light was strong, so the sky only dimmed to something like a cloudy day. Stars and the corona did not appear.
Where was the ring longest?
The longest ring, 11 minutes 8 seconds, was over the middle of the Indian Ocean. Among inhabited places, Malé in the Maldives had one of the longest, at 10 minutes 45 seconds.
When is the next longer annular eclipse?
It is calculated for 23 December 3043. Until then, the record from January 2010 will stand.
Related
- The 2028 annular over South America and Iberia
- The 2012 annular over Tokyo
- The 2027 total eclipse — six minutes of darkness
- The Moon — object index
- The Sun — object index
Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.