An annular solar eclipse occurred at the Moon's ascending node of orbit on Friday, January 15, 2010,[1] [2] [3] with a magnitude of 0.919. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide. Occurring about 1.75 days before apogee (on January 17, 2010, at 1:40 UTC), the Moon's apparent diameter was smaller.[4]
This was the longest annular solar eclipse of the millennium,[5] and the longest until December 23, 3043, with the length of maximum eclipse of 11 minutes, 7.8 seconds, and the longest duration of 11 minutes, 10.7 seconds.[6] This is about 4 minutes longer than total solar eclipses could ever get. (The solar eclipse of January 4, 1992, was longer, at 11 minutes, 40.9 seconds, occurring in the middle of the Pacific Ocean.)[7]
It was seen as an annular eclipse within a narrow stretch of 300km (200miles) width across the Central African Republic, the Democratic Republic of the Congo, Uganda, the Maldives, South Kerala (India), South Tamil Nadu (India), Sri Lanka and parts of Bangladesh, Burma and China. The eclipse was visible as only a partial eclipse in much of Africa, Southeastern Europe, the Middle East and Asia.
The eclipse started in the Central African Republic near the border with Chad, traversed DR Congo, Uganda, Kenya, passed through the northern tip of Tanzania, southwestern Somalia and three islands of Seychelles (Bird, Denis and Aride), before it entered the Indian Ocean, where it reached its greatest visibility. It then passed through Maldives. The annular eclipse at Malé, the capital city of the country, started at 12:20:17 and ended at 12:31:02 local time (UTC+5), lasting for 10 minutes and 45 seconds (645 seconds). This was also the longest duration of any eclipse with an international airport in its track.[8]
At approximately 13:20 IST, the annular solar eclipse entered India at Thiruvananthapuram (Trivandrum), the capital of Kerala and exited India at Rameswaram, Tamil Nadu.
The eclipse was viewable for 10 minutes in India. After Rameswaram, it entered Sri Lanka at Delft Island, exited at Jaffna in Sri Lanka, crossed the Bay of Bengal and re-entered India in Mizoram. Thiruvananthapuram, which was the entry point of the eclipse in India, was equipped with telescopes and announced facilities for the public to view the eclipse.[9] Vikram Sarabhai Space Centre, situated in Trivandrum, analysed the atmospheric-ionospheric parameters during the eclipse.[10] Many scientists camped in the city to witness and study the eclipse.[11]
At Rameswaram, the sunrise was not visible due to thick clouds, but it started getting clear at around 9am local time and became almost totally clear by the time the eclipse began. The sky had a thin layer of cirrus clouds till 2:30pm. Among the eclipse-watchers was Sky Watchers' Association of North Bengal (SWAN) from Siliguri at the foothills of West Bengal and Tamil Nadu Astronomical Association.
Dhanushkodi, which falls on the central line of the eclipse, was a good place to view the eclipse. The northernmost limit of shadow in India was Cuddalore, Neyveli, Erode, Kodaikanal, and Madurai. Other prime viewing locations in Tamil Nadu include Thoothukudi and Cape Comorin, 22 km north of the center line. The exact location of the line is between the NH end and the Dhanushkodi ruins. Dhanushkodi is about 2 km east of the central line. The degree difference is about 0.2 between the central line – with Kodandaramar Temple and Dhanushkodi ruins vice versa. Dhanushkodi is about 5 km from the Kodandaramar Temple.
After South Asia, the antumbra passed through the southern tip of Bangladesh, Myanmar and China before leaving the Earth.
Shown below are two tables displaying details about this particular solar eclipse. The first table outlines times at which the moon's penumbra or umbra attains the specific parameter, and the second table describes various other parameters pertaining to this eclipse.[12]
| First Penumbral External Contact | 2010 January 15 at 04:06:33.7 UTC | |
| First Umbral External Contact | 2010 January 15 at 05:15:01.1 UTC | |
| First Central Line | 2010 January 15 at 05:18:40.9 UTC | |
| First Umbral Internal Contact | 2010 January 15 at 05:22:22.0 UTC | |
| First Penumbral Internal Contact | 2010 January 15 at 06:51:13.0 UTC | |
| Greatest Duration | 2010 January 15 at 06:55:35.8 UTC | |
| Greatest Eclipse | 2010 January 15 at 07:07:39.2 UTC | |
| Ecliptic Conjunction | 2010 January 15 at 07:12:28.5 UTC | |
| Equatorial Conjunction | 2010 January 15 at 07:21:27.5 UTC | |
| Last Penumbral Internal Contact | 2010 January 15 at 07:23:43.9 UTC | |
| Last Umbral Internal Contact | 2010 January 15 at 08:52:46.6 UTC | |
| Last Central Line | 2010 January 15 at 08:56:28.9 UTC | |
| Last Umbral External Contact | 2010 January 15 at 09:00:10.0 UTC | |
| Last Penumbral External Contact | 2010 January 15 at 10:08:41.4 UTC |
| Eclipse Magnitude | 0.91903 | |
| Eclipse Obscuration | 0.84462 | |
| Gamma | 0.40016 | |
| Sun Right Ascension | 19h47m51.0s | |
| Sun Declination | -21°07'38.7" | |
| Sun Semi-Diameter | 16'15.5" | |
| Sun Equatorial Horizontal Parallax | 08.9" | |
| Moon Right Ascension | 19h47m25.3s | |
| Moon Declination | -20°46'54.8" | |
| Moon Semi-Diameter | 14'44.3" | |
| Moon Equatorial Horizontal Parallax | 0°54'05.4" | |
| ΔT | 66.0 s |
See also: Eclipse cycle. This eclipse is part of an eclipse season, a period, roughly every six months, when eclipses occur. Only two (or occasionally three) eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months (173 days) later; thus two full eclipse seasons always occur each year. Either two or three eclipses happen each eclipse season. In the sequence below, each eclipse is separated by a fortnight.