Eclipses have a more rational explanation and can now be predicted
with good accuracy for many millenniums in the past and the future
using details of the orbits of the Earth around the Sun and the Moon
around the Earth.
The Annular Solar Eclipse of 2010 January 15th which is visible in Northern Lanka, is a rare opportunity for Lankans. An Eclipse of the Sun, is one of those spectacular displays of nature one must watch in your lifetime. Although there are at least two solar eclipses each year, somewhere on earth, they are however rare in any particular location, since the path of shadow is narrow.
In the 21st century the next two Solar Eclipses to cross Lanka on 2019 December 26th and 2031 May 21st are also annular visible only in northern Lanka. After that there is a Total on 2070 April 11 and an Annular on 2074 January 27th and visible from southern Lanka, long past the lifetime of most of us.
Eclipses have fascinated and frightened humans through recorded history.
Astrologers in Lanka have imagined two planets "rahu" and "ketu" being
the head and tail of a mythical dragon to explain them.
Eclipses have a more rational explanation and can now be predicted
with good accuracy for many millenniums in the past and the future
using details of the orbits of the Earth around the Sun and the Moon
around the Earth.
The Sun is 1.4 million km in diameter and varies in distance from 152 to 147 million km resulting in an apparent angular diameter which varies from 31.6 to 32.7 minutes of arc. The Moon is 3.5 thousand km in diameter, and varies in distance between 406 thousand km at apogee to 356 thousand km at perigee. This means its apparent angular size ranges from 29.4 to 33.5 minutes of arc. The Sun is about 400 times larger in diameter than the Moon, but it is also about 400 times more distant. So coincidentally the Sun and Moon are about the same size of about half-degree as observed from Earth.
A Solar eclipse happens when the Moon in it's orbit around the Earth passes in front of the Sun. The shadow of the Moon cast on the Earth is only about 250 km in diameter. From within the track of this shadow the moon will appear directly in front of the Sun and we see an Eclipse of the Sun. If the apparent diameter Moon relative to the Sun at the time of eclipse is larger we have a Total eclipse and if smaller we have an Annular eclipse.
On Friday
2010 January 15th,
an Annular eclipse is visible in
Northern Lanka, The southern border
(Blue) of the
path crosses just north of Chilaw on the west coast and north of
Nilavali on the East coast. The border crosses south of Anuradhapura,
just north of Eppawala. The center-line (Red) crosses
Jaffna where the Annular phase will have the longest duration of over
10 minutes from about 1:20 to 1:30 PM at an altitude of 55 degrees.
About 84.2% of the center of Sun will be covered by the Moon.
The dark Moon will be seen in front of the Sun, leaving a 15.6% of the Sun
still visible as a bright ring of Fire.
Because the Sun passes through perigee on Jan 3rd and Moon passes through apogee two days after Eclipse (Jan 17 at 01:41 UT), its large distance from Earth produces an unusually wide path of annularity. The instant of greatest eclipse occurs at 07:06:33 UT when the eclipse magnitude will reach 0.919. At this location in the Indian Ocean just west of the Maldives, the duration of annularity is 11 minutes 8 seconds. Such a long annular duration will not be exceeded for over 1000 years (3043 Dec 23).
shadowandsubstance.com provide a very nice Shock Wave annimation of the Annular Eclipse of 2010 January 15th, showing simultaneously how it will appear at different locations on Earth.
The Nautical Almanac Office Eclipse website has some useful eclipse animations for few major cites in Lanka.
North of the southern border and far from the
center-line the ring will appear non Symmetrical with one side much thinner.
About a kilometer just north of the southern border, although the
Annularity will be very short, the Moon will graze the edge of the
Sun, and one would observe interesting phenomena such a Baily's beads not
seen further in towards the center-line. From south of this border we see only a partial eclipse.
For example from Colombo, the Sun will be visible like a thin crescent.
In Lanka the partial Eclipse begins few minutes after 11:13 AM and ends
before 3:12 PM.
Weather can always be a spoiler when hoping to watch any astronomical event. Satellite images of Lanka taken around Noon in January over the last 3 years: 2007; 2008; 2009, shows that it is cloud free in the northern part of Lanka 80 to 85% of the days. The Noon time January weather leading up to eclipse can be seen in 2010, and the last 2 days in weather. In any case as long as you can see the Sun you get a good view of an Annular Eclipse. Unlike in a Total eclipse which requires it to be perfectly clear to see the corona, that in any case is not seen in an Annular.
The only time that the Sun can be viewed safely with the naked eye is during a total eclipse, when the Moon completely covers the disk of the Sun. It is never safe to look at a partial or annular eclipse, or the partial phases of a total solar eclipse, without the proper equipment and techniques. Even when 85% of the Sun's surface is obscured during the Annular phases of this solar eclipse, the remaining crescent Sun is still intense enough to cause permanent retinal damage, especially when viewed through binoculars or other optical aids. Unfiltered Digital cameras will get destroyed.
The Sun is 400,000 times brighter than the full Moon. To reduce observed brightness of the Sun to that of the full Moon, we need to filter out 99.99975% of the sunlight. This can be done using eclipse solar filters made from for example Mylar foil. One can also use Electric Welders Glass as a filter. They are available at many local hardware shops for under Rs60/-. The recommended shade 14 is not available in Lanka. Shade 12 or 13 are OK. Although not as good as proper filters, the packaging used for Milk powder can be used since they are designed to keep out harmful UV light. The Highland brand with a white inner surface is nice since you don't see a reflection. These filters are opaque, other than when looking at Sun. If used with an optical instrument such as a Telescope or Binocular the filtering MUST be at the objective BEFORE light enters the instrument. Make sure you don't leave any pin holes.
I am amazed as to how many who have never even seen a Solar Eclipse, will gladly talk about it to an equally ignorant journalist, resulting in some totally misleading and sometimes hilarious information being published in both the English and Sinhala media. In a nation which believes in pseudo astrology, I am sure it is just a matter of time before quacks start using it to predict influence on local events and politics. However, there is absolutely no influence on any person by any of these celestial events.
The last Solar Eclipse to cross Lanka was on 1955 June 20th and was a Total. It gathered the largest number of professional astronomers in Lanka. Unfortunately most of these teams located in the Polonnaruwa district were clouded out. Limited observations were done from Sigiriya, and by amateurs from Kalkudah on the East coast.
The 1955 Eclipse is still remembered by all who saw it, or did not watch it because of ignorant superstition. A quack physician cum astrologer, recommended that women wanting to become get fair and lovely should drink a decoction which the main ingredient was "Vada Kaha" (Sweet Flag or Acorus Calamus) at the time of the total eclipse, preferably unseen by any others. Many who took the advice ended up in Hospital. The story of the "wada kaha sudiya" in remembered in a popular baila.
A solar Eclipse is event which must be experience and observed. No video can do justice to that experience. It can also become addictive. In the modern age when the Internet and TV can bring events to your home, one may wonder why some Eclipse chasers travel round the world to see an Eclipse of the Sun. When you see one of these glorious spectacles of nature the reason would be obvious. I was too small to remember the 1955 eclipse. I have read it was cloudy in Colombo anyway. The first annular I saw from USA on 1994 May 10th. Then I traveled to see Totals in 1994 Nov 3rd from Bolivia, 1995 Oct 24th from India, and 1998 February 26th from the Caribbean.
An Annular Eclipse of the Sun although not as spectacular as a Total
is worth the effort to watch, particularly since you don't need to
travel very far even from southern Lanka. Since the A9 is now open
without restriction, there is lot more to see in the North, that many
have not visited for over 20 years. January 15th is a Friday and the
14th is Thai Pongal, a public holiday. What better way than for the
residents of the south to travel North and celebrate Thai Pongal with
our northern brethren and watch the eclipse the next day.
We hope the weather will be favourable for this eclipse. I hope to see from Jaffna. Annular Solar Eclipse will be streaming live from Jaffna on the Internet via eclipse.skylk.com. The stream will be open through out the eclipse.
