Thanks to Alan Mason for this post on Solar Eclipse
The partial eclipse over Britain on Friday 20 March, at the nice convenient time of 9.30 am, seems likely to be shrouded by clouds in our barely predictable oceanic climate. Despite the media excitement, they rarely stress that this is only a partial eclipse. This may be a good time to remind ourselves of the awesome spectacle of a full total eclipse.
The first image is a painting in acrylics, made several days after the eclipse. As readers might expect, it is rather too dark to paint successfully during an eclipse, and there is not much time anyway, as totality only lasts for a couple of minutes (1). The main features are the darkness of the sky in the middle of the day, the pattern of small clouds, barely visible, the eerie, lilac colour of the solar corona, and the jagged outline of the moon’s disc.
The second image (2) is more accurate, and is based on “500 hours of hard work” by Steve Albers in computer-enhancing the photographs taken on the 11 July 1991 by Dennis di Cicco and Gary Emerson. This eclipse was seen from Hawaii, Mexico, Central America and northern states of South America.
I have made use of an excellent book, (References A) on solar eclipses for illustrations and for the rather poetic text which follows.
“THE EXPERIENCE OF TOTALITY
‘Some people see a partial eclipse and wonder why others talk so much about a total eclipse. Seeing a partial eclipse and saying that you have seen an eclipse is like standing outside an opera house and saying that you have seen the opera; in both cases, you have missed the main event.’
—Jay M. Pasachoff (1983)
First contact. A tiny nick appears on the western side of the Sun. The eye detects no difference in the amount of sunlight. Nothing but that nick portends anything out of the ordinary. But as the nick becomes a gouge in the face of the Sun, a sense of anticipation begins. This will be no ordinary day.
Still, things proceed leisurely for the first half hour or so, until the Sun is more than half covered. Now, gradually at first, then faster and faster, extraordinary things begin to happen. The sky is still bright, but the blue is a little duller. On the ground around you the light is beginning to diminish. Over the next 10 to 15 minutes, the landscape takes on a steel-gray metallic cast (3).
Even if you have never seen a total eclipse of the Sun before, you know that something amazing is going to happen, is happening now—and that it is beyond normal human experience. Less than 15 minutes until totality. The Sun, a narrowing crescent, is still fiercely bright, but the blueness of the sky has deepened into blue-gray or violet. The darkness of the sky begins to close in around the Sun. The Sun does not fill the heavens with brightness anymore.
Five minutes to totality. The darkness in the west is very noticeable and gathering strength, a dark amorphous form rising upward and spreading out along the western horizon. It builds like a massive storm, but in utter silence, with no rumble of distant thunder. And now the darkness begins to float up above the horizon, revealing a yellow or orange twilight beneath. You are already seeing through the Moon’s narrow shadow to the resurgent sunlight beyond.
The acceleration of events intensifies. The crescent Sun is now a blazing white sliver (4), like a welder’s torch. The darkening sky continues to close in around the Sun, faster, engulfing it.
Minutes have become seconds. The ends of the bare sliver of the Sun break into individual dots of intense white light—Baily’s Beads (5, 6) —the last rays of sunlight passing through the deepest lunar valleys. Opposite the beads, a ghostly round silhouette looms into view. It is the dark limb of the Moon, framed by a white opalescent glow that creates a halo around the darkened Sun. The corona, the most striking and unexpected of all the features of a total eclipse, is emerging.
Along the shrinking sliver of the Sun, the beads flicker, each lasting but an instant and vanishing as new ones form. And now there is only one, set like a single diamond in a ring (7). The remaining one small dot of sunlight fades as if it were sucked into an abyss.
Where the Sun once stood, there is a black disk in the sky, outlined by the soft pearly white glow of the corona, about the brightness of a full moon. Small but vibrant reddish features stand at the eastern rim of the Moon’s disk, contrasting vividly with the white of the corona and the black where the Sun is hidden. These are the prominences, giant clouds of hot gas in the Sun’s lower atmosphere. They are always a surprise, each unique in shape and size, different yesterday and tomorrow from what they are at this special moment.
You are standing in the shadow of the Moon.
Now, at the midpoint in totality, the corona stands out most clearly (1, 2), its shape and extent never quite the same from one eclipse to another. And only the eye can do the corona justice, its special pattern of faint wisps and spikes on this day never seen before and never to be seen again.
Yet around you at the horizon is a warning that totality is drawing to an end. The west is brightening while in the east the darkness is deepening and descending toward the horizon. Above you, prominences appear at the western edge of the Moon. The edge brightens.
Suddenly totality is over. A dot of sunlight appears. Quickly this heavenly diamond broadens into a band of several jewels and then a sliver of the crescent Sun once more. The dark shadow of the Moon silently slips past you and rushes off toward the east.
It is then you ask, “When is the next one?”
Eclipse Tour, 1999
Phil Krause and I went on a three-day coach excursion to France, to see the eclipse. We all stayed in motel on the outskirts of Dunkirk. On arrival, as the motel was not yet ready for us, we were all dumped in the centre of Dunkirk and left to our own devices for the day. Months later, I was describing this to a friend in Hampshire. She said,
“How did you like Dunkirk?”
I replied, “We loved it. The little harbour had small boats, a square-rig sailing ship, and shops all around it. The canal winds through a pretty public park, and the main street is attractive with restaurants and boutiques, leading to the medieval tower on the beach front. We had a great meal in a workmen’s café.”
My friend, who used to be my boss, murmured to her husband, “I said we were in the wrong part of town, John.” They had once stayed overnight in a hotel near the industrial end of Dunkirk, and thought it was one of the worst towns they had ever seen.
The second day was, “Eclipse Day” and we left early to drive the 80 miles, (128 Km) from Dunkirk to Amiens, with its magnificent cathedral (8, 9), where we were dropped at a big public park, in good time. The civic authorities of Amiens deserve great praise for their organisation. Free “eclipse spectacles” were given out, along with free maps of the city of Amiens, and there was a PA system to describe the eclipse, in French and English, for the viewers. The young man giving the commentary was a model in how to do this. He used a few short sentences to describe what we could currently see, and then he shut up.
Phil and were stationed by a dual carriageway on a rise because we wanted to see the moon’s shadow rushing across the landscape towards us, but we were unlucky. It requires forward planning and a really careful choice of site on a hilltop above a plain to see this effect. I was surprised at the motorists driving along the dual carriageway with their lights on (10), ignoring this once-in-a-lifetime spectacle.
A French sales rep, recruited from “Allo, ‘allo” arrives at his destination.
“Good moaning. I was ordaired to drive from Amiens weez tree satchels of cernderms to zee herhouse here een Bayeux. I am serry to be late but I ‘ad to sweetch my ferking ‘eadlights on in zer meedle of zer ferking day.”
We had a good view of the eclipse, and although the sky was not totally clear, the pattern of small clouds, (1, 7, 4,) did not obstruct our view, and actually added to the interest. When the period of totality was over we left early to get into town for some lunch before the rush started (11). An elderly man opened his front door and bleary-eyed, asked hoarsely, “C’est fini, c’est fini?” We replied, “Oui, oui, c’est ca. C’est fini”. (Is it over? Yes, that’s it. It’s over.) We heard later he went into the back garden and shot himself. (No, I just made that up.)
When Phil and I reached the city centre from the park, we headed for a restaurant and had an excellent lunch (11). There is nothing like an eclipse for sharpening your appetite. In the afternoon we spent some time looking round the Cathedral (12). On the third day we visited the town of St Omer, and were equally charmed by its attractive centre, particularly the fine museum, and its cathedral. It was only on our return journey to England, through the Channel Tunnel, that trouble struck on our “Eclipse Break”.
The coach burst a tyre on the M25 and pulled over on to the hard shoulder. The coach firm reacted to this event as if it was the first time in recorded history that such a happening had ever occurred before. They should either have sent, or chartered, a relief coach to take the passengers home, or had a crew sent to change the wheel quickly. In the end, Phil rang his wife, asked her to find a local taxi firm, book them to come out immediately to the crippled coach and take three of us home. As a friend of mine once observed, “One of the functions of money, is to buy yourself out of trouble.”
Serious eclipse watchers are strongly recommended to get a copy of “Totality” (13) which explains all the technicalities, as far as you are likely to need, in very clear language without mathematical equations. It also gives lots of incidental information, like Scotland had three total eclipses in a 56 year period (1598 – 1654), or Brisbane, Australia had two in less than a year (1856-7). No one in Scotland saw the eclipses because it was cloudy and wet, and only the convicts saw the Australian eclipses.
You can learn a new word, “saros”, to describe eclipse-predicting rhythms, discovered by Chaldean astronomers, in the Middle East around 800 – 750 BC.
REFERENCES AND ILLUSTRATIONS
A. “Totality – “Eclipses of the Sun” by Mark Littman, Ken Willcox and Fred Espenak, Oxford UP, 1999
B. “British Architecture and its Background” by John B Nellist, Macmillan, 1967
C. “The Lion Companion to Church Architecture by David Stancliffe, Lion, 2008
1. An impression of the total eclipse of 11 August 1991, in Amiens, northern France (Author)
2. Computerised composite of five eclipse photographs (References A)
3. Centre of Amiens showing the sky when approaching totality (Author)
4. “A blazing white sliver” (Author)
5. “Baily’s Beads” photograph of eclipse 30.5.1994 S Carolina (References A)
6. Francis Baily first described his beads on 15.5.1836 (References A)
7. “A single diamond in a ring” from the 1999 eclipse in Amiens (Author)
8. West Front, Amiens Cathedral (References B)
9. Amiens Cathedral (References C)
10. Headlights for eclipse (Author)
11. Lunch (Google image)
12. Amiens Cathedral, nave looking east (References B)
13. “Must-have” for eclipse-watchers (References A)