A solar eclipse occurs when the Moon gets in the way of the Sun. However, if the Moon only covers part of the Sun (even up to 95%) it is likely to pass unnoticed, unless someone has previously drawn your attention to it and you have some darkened filters to look through. The Moon needs to cover the Sun totally for the full and dramatic effects to be seen with the naked eye.
The
Moon varies in apparent size because its orbit is elliptical. At times
when it is furthest from the Earth the Moon appears 11% smaller than the
Sun and cannot block out the Sun totally from anywhere on Earth. However,
when the Moon is closest to the Earth it is over 6% larger than the Sun
and hence can totally cover the Sun, provided you are situated exactly
at the right location on the Earth. This location is precise because the
Moon's shadow on the Earth can be no larger than 170 miles across. In Cornwall
in 1999 its shadow will be 65 miles across.
As you can see from the map, Scilly lies well within the shadow and we will get 1 minute 42 seconds of darkness. Although Scilly will not get the longest amount of darkness (those areas closest to the centre line in Cornwall will only get another 20 seconds!), we will be the first to see the eclipse and we have a higher chance of clear skies than the mainland.
One major problem is that total eclipses actually generate clouds. Within the Moon's huge dark shadow it is many degrees cooler than outside, and as the shadow rushes at 1,000 mph across the globe the weather can change before your very eyes - clouds can form in seconds in a cloudless sky.
Unfortunately you do need a cloud free view of the Sun to see the full
splendour of totality. If the sky is overcast everything will go as dark
as a summer midnight, but you'll not witness your life-giving Sun swallowed
into a pitch black hole, surrounded by eerie, wispy, glowing streamers.
You will see the most magnificent sight that you have ever beheld. No, I'm not exaggerating, after all why would I have travelled to the frozen Siberian wastes in March 1997, flown for 8 hours from Moscow by Aeroflot, and stood in -24 degrees of cold to see one otherwise? Why did ancient civilisations make human sacrifices, or start wars when they saw a total eclipse?
No description, photograph or video can do an eclipse justice, after all how can you accurately describe a smell, taste, or sensation? Wine writers have incredible trouble describing the taste of wines using terms such as - appley, plummy, zingy to do them justice. I am just as unlikely to succeed but I'll have a go anyway:
"It is mid morning, and the day is progressing normally. It is 10:15 summer time (GMT + 1 hour), and the Moon has just made contact with the Sun. There is not the slightest evidence of anything unusual - it could be a day like any other. The only way you could possibly tell is by looking through a Mylar filter, or seeing the Sun projected through a telescope. Half an hour goes by (10:45) and you are starting to get bored. 15 minutes before totality (11:00) and you can be forgiven for feeling a slight chill, the wind seems to be building up. You look around and there is something distinctly wrong, but you can't put your finger on it. Shadows start to get crisper. Under trees or foliage you may see numerous crescent-shaped Suns projected on the ground through the leaves. Five minutes to totality and you should see the sky to the west (the opposite horizon to the Sun) getting darker. The Moon's shadow is now only 100 miles away and closing in on you at 1,000 miles an hour. Keep looking west and with only 30 seconds to go, the shadow is less than 10 miles away. It will be visible as a dark veil edged in orange sweeping across the sky and engulfing the landscape. Your whole body goes cold and shivery with trepidation and there is nothing you can do about it. Animals rush for cover or do what they would do as night approaches. It feels as if the world is coming to an end, the darkness is too sudden for nightfall, and too dark for clouds.
Suddenly everything goes dark - quickly you look at the Sun with your naked eyes and see a magnificent Diamond Ring of light - this is the last tiny portion of the Sun shining though a mountain valley on the Moon. Within 5 seconds the ring is gone and totality is complete. You probably want to cry as you stare at what's left of the Sun. A huge black hole replaces your beloved Sun, and this hole is surrounded by the glowing outer atmosphere of the Sun. During totality it is safe to look through binoculars and you may see a solar prominence. In the time that remains (probably less than a minute) have a look at the sky close to the Sun, you will see two bright points of light, these are Mercury to the right and Venus to the left of the Sun. Look at the horizon, remember that you are in the middle of a huge shadow, you should be able to see blue skies where the Sun is still shining in the far distance. Take one last look at the Sun, and soon pinpricks of dazzling light (Baily's Beads) will appear on the opposite side of the Sun to the first Diamond Ring. It is dangerous to look any longer with the naked eye as totality is over.
Events
now take place in reverse order, but it is rather an anticlimax and time
to crack open the champagne. Why not plan your next total eclipse - on
the beach surrounded by ring-tailed lemurs in Madagascar on Midsummer's
day in 2001 sounds very civilised - see you there"
This information was provided by Sheridan Williams, author of this
great book:
UK Solar Eclipses From Year 1 by Sheridan Williams
For details on How to observe, Where to observe, Safety, Mylar filters,
Photographic hints, Mechanics of Eclipses, List of all eclipses until 2015,
comprehensive details of all UK Eclipses from 1 - 3000AD.
Published by: Clock Tower Press, PO BOX 5010, Leighton Buzzard, LU7
0ZZ
Email: sales@clocktower.demon.co.uk
Price £11.95 + £1 p&p. UK ( £2 overseas), cheques
payable to Clock Tower Press
Click
here for more details of the book
| Latitude | Longitude | Start time | Mid-point | End time | Duration (min:sec) | Altitude(degrees) |
| 49o55' | 06o15' | 08:55:42 | 10:10:30 | 11:30:24 | 1:42 | 45.4 |
see also Accommodation and Travel pages.
Goddard's Solar Data Analysis Center (SDAC) - for NASA eclipse buletins, path tables, still and moving pictures and loads more...
Eclipse99 Ltd - suppliers of protective filter solar eclipse viewers and other products related to the 1999 eclipse
Hermit Eclipse Page - more stuff on the 99 eclipse
Romanian Space Agency Eclipse Website
