Solar Eclipse of 11th August 1999
- Eclipse Path
- Eclipse Types
- Web Links
- Further Reading
The first total solar eclipse visible from the United Kingdom mainland
for more than 70 years occurs on the morning of Wednesday, 11 August 1999, soon
after 11:00,a.m. Previous total eclipses visible from the UK this
century were those of 29 June 1927 and 30 June 1954; the latter, however,
was visible only from the northernmost part of the Shetland Islands.
Although the partial phase of the eclipse will be visible from the whole
of the British Isles, the path of totality across the country is rather
short, being limited to a strip which crosses the Isles of Scilly, most
of Cornwall except the northern part, southern Devon and Dorset as far as
Torquay, and the Channel Island Alderney.
Figure 1: Total eclipse track, after Espenak & Anderson (1997). (Click on the image for high quality figure.)
Weather prospects for viewing the eclipse are only moderate in the UK,
and those wishing to be certain of seeing the event are advised to travel
to a part of Europe where cloud is less likely to be a problem.
Anyone wishing to view the total eclipse at its best is strongly advised
to travel to a place where the Moon completely covers the Sun, as only
there will the full beauty of the event be seen. The track of the Moon's
shadow on the Earth, known as the path of totality, will pass over many
towns and cities of Europe and Asia, thus giving many millions of people
the opportunity to witness this rare and wonderful spectacle. Some of the
towns include Cherbourg and Reims in France, Stuttgart and Munich in
Germany, Timisoara and Bucharest in Romania, Sivas and Diyarbakir in
Turkey, Irbil and As-Sulaymaniyah in Iraq, Esfahan in Iran, Karachi in
Pakistan, and Baroda and Akola in India.
The maximum possible duration of the total eclipse is 2m 23s, occurring
near Rimnicu-Vilcea in Romania. The duration of the total phase of the
eclipse ranges from 2m 2s at Falmouth, England, 2m 13s at Metz, France,
2m 17s at Stuttgart, Germany, 2m 7s at Sivas, Turkey, 1m 33s at Esfahan,
Iran, 1m 13s at Karachi, Pakistan to 52s at Chandrapur in India.
The times of the total eclipse for selected United Kingdom, Western and
Eastern European towns and cities are given in Table 1.
given according to British Summer Time (BST); add 1 hour to obtain local
times in France, Germany, Austria, Hungary and Romania. The start of the
partial phase of the eclipse is denoted `first contact', while `second
contact' denotes the start of totality. The total phase finishes a couple
of minutes later at `third contact,' while the remaining partial phase of
the eclipse can then be viewed up to eclipse end at `fourth contact'. The
times of the eclipse for towns and cities where only a partial eclipse is
visible are given in Table 2.
The northern limit of the
eclipse path lies some 70 miles off the coast of southwest
Ireland. Consequently, no place in Ireland will experience a total
eclipse. At Cork, for instance, the eclipse magnitude will be 97%.
Although Cornwall has some of the best summer weather in England, there
is still only a 45% probability of it being clear there at the time of
the eclipse. The probability of seeing the eclipse increases the further
east one goes. For instance, Munich has a probability of 50%, Bucharest
60%, Sivas in Turkey 75%, and Esfahan in Iran 95%.
Figure 2: Path of totality across Europe, after Espenak & Anderson (1997). (Click on the image for high quality figure).
Table 1: Times of the eclipse to the nearest second (BST) for selected towns and cities lying on the path of totality.
| || || 1st Contact || 2nd Contact || 3rd Contact || 4th Contact || |
|Country|| Town || || Totality|
|England|| Bodmin || 09:57:51 || 11:12:22 || 11:13:41 || 12:33:00 || 1m 19s|
| || Camborne || 09:56:58 || 11:11:02 || 11:13:03 || 12:32:03 || 2m 01s|
| || Falmouth || 09:57:08 || 11:11:19 || 11:13:22 || 12:32:28 || 2m 02s|
| || Helston || 09:56:54 || 11:11:02 || 11:13:03 || 12:32:09 || 2m 01s|
| || Hugh Town, Isles of Scilly || 09:55:45 || 11:09:43 || 11:11:24 || 12:30:30 || 1m 41s|
| || Newton Abbot || 09:59:00 || 11:14:21 || 11:14:51 || 12:34:47 || 0m 30s|
| || Penzance || 09:56:39 || 11:10:39 || 11:12:41 || 12:31:41 || 2m 02s|
| || Plymouth || 09:58:17 || 11:12:54 || 11:14:33 || 12:33:54 || 1m 39s|
| || Redruth || 09:57:04 || 11:11:09 || 11:13:10 || 12:32:11 || 2m 01s|
| || Saltash || 09:58:16 || 11:12:54 || 11:14:29 || 12:33:51 || 1m 35s|
| || Torquay || 09:59:02 || 11:14:08 || 11:15:15 || 12:34:58 || 1m 07s|
| || Truro || 09:57:18 || 11:11:28 || 11:13:25 || 12:32:29 || 1m 57s|
|France || Cherbourg || 10:00:11 || 11:16:11 || 11:17:45 || 12:38:11 || 1m 35s|
| || Le Havre || 10:02:03 || 11:18:49 || 11:20:20 || 12:41:14 || 1m 31s|
| || Metz || 10:09:13 || 11:27:56 || 11:30:09 || 12:51:35 || 2m 13s|
|Germany|| Augsburg || 10:15:26 || 11:35:53 || 11:38:10 || 13:00:04 || 2m 17s|
| || Munich || 10:16:21 || 11:37:12 || 11:39:20 || 13:01:26 || 2m 08s|
| || Stuttgart || 10:13:09 || 11:32:55 || 11:35:12 || 12:56:54 || 2m 17s|
|Austria|| Graz || 10:22:09 || 11:44:57 || 11:46:09 || 13:08:56 || 1m 12s|
| || Salzburg || 10:18:28 || 11:39:55 || 11:41:58 || 13:04:11 || 2m 02s|
|Hungary|| Szeged || 10:30:04 || 11:53:22 || 11:55:43 || 13:17:22 || 2m 21s|
|Romania|| Bucharest || 10:41:25 || 12:05:48 || 12:08:10 || 13:28:44 || 2m 22s|
Table 2: Times of the eclipse for towns lying off the path of totality. The eclipse magnitude is the maximum fraction of the Sun's diameter
obscured by the Moon.
| Town || Start || Maximum || End || Magnitude|
| Belfast || 10:01:37 ||11:14:04 ||12:30:32 || 89|
| Birmingham|| 10:02:52 ||11:17:59 ||12:37:00 || 94|
| Cardiff || 10:00:23 ||11:15:37 ||12:35:12 || 97|
| Cork || 09:56:03 ||11:09:06 ||12:27:07 || 97|
| Dublin || 09:59:43 ||11:12:49 ||12:30:17 || 92|
| Edinburgh || 10:05:47 ||11:18:04 ||12:33:45 || 85|
| Limerick || 09:56:52 ||11:09:28 ||12:26:53 || 94|
| Liverpool || 10:02:51 ||11:17:02 ||12:35:05 || 92|
| London || 10:03:34 ||11:19:51 ||12:39:57 || 97|
| Londonderry||10:00:59 ||11:12:42 ||12:28:32 || 88|
| Oxford ||10:02:41 ||11:18:27 ||12:38:10 || 96|
| York ||10:05:18 ||11:19:40 ||12:37:30 || 90|
The Earth orbits the Sun making one complete revolution in one year.
Similarly, the Moon is in orbit around the Earth. Occasionally all three
bodies, Sun, Moon and Earth lie in a straight line. As it happens, the
angular diameters of the Sun and Moon are very nearly the same. The Sun
is about 400 times larger than the Moon, but is also about 400 times
further away. When all three bodies, Sun, Moon and Earth lie in a
straight line with the Moon in the centre, the Moon will completely cover
the Sun and we have the phenomenon of a solar eclipse.
Figure 3: How eclipses occur. The Sun (at left) casts a shadow of the Moon
on to the Earth (at right). The diagram (not to scale) illustrates the three
different types of solar eclipse.
In practice, the angular diameter of the Moon varies depending on its
distance from the Earth. For a total eclipse to occur, the Moon's angular
diameter must be greater than that of the Sun. The length of totality
depends on how much larger than the Sun the Moon is, with the maximum
possible duration of totality being about 7m 30s. Occasionally, the Moon
is too far away to completely cover the Sun, and in this case the eclipse
is called annular. The various types of solar eclipse are illustrated in
Permanent damage will be caused to the retina of the eye if proper
precautions are not taken while observing the Sun.
to the retina can occur without pain and the results may not be
noticeable for some hours after the damage has been done. Viewing a
partial solar eclipse, annular solar eclipse, or the partial phase of a
total solar eclipse should not be attempted without some form of eye
protection or the use of an appropriate observing method.
Never stare at the Sun. Even if only 1% of the Sun's disc is
visible, it is still bright enough to cause damage.
Children, especially, should be well supervised.
The projection method is the safest way to observe the Sun. By means of a
pinhole in a piece of card, cast the Sun's image onto a screen about 1
metre away. Another method is to use a small mirror to reflect the Sun's
image onto a shaded wall. A third is to use a small telescope or a pair
of firmly mounted binoculars to focus a larger solar image on a white
screen - but guard against anyone looking directly through the
instrument. Tape down the cover on the front lens of any attached finder
telescope. Alternatively, proper solar filters made from metalized glass,
or mylar, may be used to view the eclipse directly. Solar filters must be
placed securely over the front of the telescope so that the Sun's light
is filtered before it enters the instrument. Appropriate solar filters
may be obtained from photographic suppliers or a variety of other
sources, such as Eclipse 99 Ltd., Belle Etoile, Rue du Hamel,
Guernsey GY5 7QJ.
Do not observe the Sun with materials such as
ordinary photographic filters, exposed photographic film, or coloured
plastic, as these may not filter out the highly dangerous infrared and
ultraviolet radiation from the Sun. Only the total phase of the solar
eclipse may be viewed directly without filters.
A 35mm camera with a long-focus lens, say 200 to 400mm, mounted on a
firm support will be sufficient to capture a reasonably large image (1.9
to 3.8mm) of the Sun in eclipse together with its surrounding corona.
With a 1000mm lens, the image should nicely fill the 35mm frame. To
photograph the partial phase of the eclipse, a mylar or glass solar
filter must cover the lens for safety reasons. For information on where
to obtain filters, see the suggestions for further reading.
The exposure time depends on the filter/film combination, and for best
results one should experiment with various times on the uneclipsed Sun.
This requires preparation! Photograph the noon Sun with your chosen
filter at a fixed aperture, say f/8 or f/16, and with a range of times
from 1/4s to 1/1000s. Select the best image from the developed
negative and use the corresponding exposure time and aperture to
photograph the partial phase of the eclipse. During the thin crescent
phase of the eclipse, that is, shortly before and after totality,
increase the aperture by two stops, for example from f/11 to f/5.6. It is
advisable to make a series of bracketed exposures, that is, to vary the
exposure times on either side of the original settings in case there is
haze or thin cloud on the day of the eclipse. For photography during the
period of totality, which lasts for about 2 minutes, remove all solar
filters. Using ordinary daylight film (e.g. 200 ASA), exposures of
around 1/4s at f/8 or f/11 should be sufficient to capture the corona,
while the brighter chromosphere requires much shorter exposures of about
1/1000s at f/16 or f/22.
As the Moon passes in front of the Sun, a small `bite' of increasing
size slowly develops. Shortly before totality begins, the thin crescent
of the Sun will be broken by the irregular edge of the Moon, caused by
lunar mountains and craters, producing the effect known as Baily's Beads
(a string of points of light). Then, immediately before totality, the
Diamond Ring effect occurs, where the last point of light from the Sun
produces a stunning effect on photographs.
With the reduced glare of the Sun comes the rare opportunity to view the
Sun's outer atmosphere. The inner part of this region, known as the
chromosphere, comes into view first, together with the reddish
prominences, huge arches of hydrogen gas caused by giant eruptions on the
Sun. Further out lies the solar corona, the very high temperature
component of the Sun's atmosphere composed of gas streaming away from the
The lower part of the Sun's atmosphere is characterized by strong
magnetic fields and strong turbulence. This is where solar storms are
generated. If the storms build up sufficiently, gas can explode away
from the Sun and produce a stream of electrically charged particles.
These particles may reach the Earth and interact with our atmosphere,
causing radio interference and auroral displays. It has been known for
several decades that the corona has a temperature of more than one
million degrees, although the precise mechanism by which this is
maintained remains a mystery. Prior to 1975, the best ultraviolet and
X-ray observations of the corona and the boundary layer lying between the
corona and the chromosphere, known as the transition region, were
obtained by the NASA-launched SKYLAB
spacecraft mission. Since then,
there have been several important space missions, the most recent being
(Japanese for Sunbeam) and SOHO
(Solar and Heliospheric
Observatory). Astronomers at the Armagh Observatory have been actively
involved in both these missions. The new picture which is emerging is one
of a finely structured, highly dynamic environment.
Further details and links to other sites may be
found at G. Doyle's Home Page
Other occurrences noticeable just prior to, and during totality are
possible shadows coming in waves across the Earth's surface, and changes
in the bird and animal kingdoms, such as birds beginning to roost for the
There are many sites on the internet specialising in solar eclipses, and
some with particular information on the 11 August 1999 eclipse. These
- Andrews, A.D., 1998. A Guide to Locations in Cornwall for
Observations of the Total Eclipse of the Sun 11th August 1999, The
Irish Astronomical Journal, Vol.25, No.1, p.57.
- Bell, S., 1997. The RGO Guide to the 1999 Total Eclipse of
the Sun, HM Nautical Almanac Office, Royal Greenwich Observatory,
- Chou, B.R., 1998. Solar Filter Safety, Sky and Telescope,
February 1998, p.36.
- Espenak, F. & Anderson, J., 1997. Total Solar Eclipse of
1999 August 11, NASA Reference Publication No.1398.
- MacRobert, A.M., 1998. The February 26th Eclipse of the Sun,
Sky and Telescope, February 1998, p.82.
- Williams, S., 1996. UK Solar Eclipses from Year 1:
An anthology of 3000 years of solar eclipses, Clock Tower Press.
- Zirker, J.B., 1984. Total Eclipses of the Sun,
Princeton University Press, Princeton, 1984.
Last Revised: 2010 February 22nd