Eclipse
Eclipses are one of the most beautiful things to be seen in Astronomy you only need solar filters for the partial phase. Once the eclipse is total you can view it with the naked eye. If you wish you can take photographs or Video the Eclipse. But do look at it and enjoy the sight.NEVER LOOK AT THE SUN WITHOUT SOLAR FILTERS YOU WILL DAMAGE YOUR SIGHT
Eclipses
Eclipses are caused by a chance alignment between the Sun and Moon. There will only be a solar eclipse if the moon is at new. The Sun also has to be close to one of its nodes. This means that the Sun must be close to one of its two nodes of the moons orbit at the same time that the moon is crossing the node Solar Eclipses can occur 18 days of a node passage. At other times other than other nodal encounters, the moon would appear to pass north or South of the sun (or of the earth's Shadow) in this case there will no Eclipse. This is what gives this the qualification to allow Eclipse Seasons,and times of year when eclipses can occur.
Eclipse Seasons
When the lines of the node in moons orbit are at right angles to the sun-Earth line, the moon is crossing a node while in the first quarter phase. At full or new moon is passing north or south of the sun and no Eclipse is possible. Therefore there can only be a Solar or Lunar Eclipse Six mouths apart when the line of nodes is aligned with the sun moon is near one of its nodes. These positions are called eclipse seasons. Because of Regression of nodes a 19 degree clock wise shift in the positions of the of nodes occurs during the calendar year. Because the earth moves around its orbit by one degree a day. The time it takes for the same node to make its second consecutive alignment with the sun. This is called an Eclipse year.The Eclipse year is shorter than an earth year by just over 19 days Therefore if the eclipse starts in January, it is possible that there can be three eclipse seasons, the last falling in December.
Behavior of Man
The most dramatic responses comes from Greek writings around 430 BC. war had broken out between the Lydains and the Medes.These were major powers in Asia Minor.The war had been going for five years with no side winning or losing. Because of this another battle took place in the sixth year. During the course of this battle the day was turned to night. When the Medes and the Lydians observed the change, ceased fighting and had terms for peace agreed. Herodotus tells of another turning point in history that is hinged on a solar eclipse. Xerxes and his Persian army were about to march to Greece. He reached and burned Athens but his navy were destroyed by the Greeks and his army had to with draw. Xerxes invaded Greece two more times his army were Crushed .After his last defeat ,his nobles assassinated him. These are just two examples of many that I could of used.
Animal Behavour
Animals use there primal response to the darkening of the daytime sun. Reports go back more than 750 years. The report by Ristoro d'Aresso from the 1239 eclipse. This stated that as the sun was covered step by step. It became night and the animals and birds were terrified; and the wild beasts could be easily caught because they were bewildered. There is a report from the eclipse of 1560 by a student in Portugal. "stars appeared in the sky and the birds fell down from the sky to the ground in terror of such horrid darkness". In 1706 observers reported that bats flitted about as the beginning of night. Fowls and pigeons ran to their roosts. In 1715 Jacques Eugene d' Allomville,Chevalier de Louville went to London to see a total eclipse. He reported that "horses that were labouring or employed on the high roads lay down. They refused to advance"
Future Eclipses
Types of Eclipses
There are two main types of eclipses which I will tell
you about here. But first I will tell you how an eclipse happens. As you will know the sun is much larger
than the moon. In fact the sun is 400 times larger than the moon but as luck would have it the moon is 400 times further
away from the sun. This gives it a angular diameter the same as the sun. So we can see a solar eclipse but this will not always be the case
as the moon is slowly moving away from the earth. This is a simple way of explaining a difficult topic.
The first type of eclipse I will explain is an Annular eclipse. This happens when the moon does not completely cover the sun
and a ring of sunlight is left around the edge of the sun. This happen because the Umbral shadow (THE DARKEST PART OF THE MOONS SHADOW)
varies between 367,400km and 379,900 km in length and this can be a short fall of 32000km. Because the earth is not a true sphere but bulges giving it the shape
of a pear. This means that when the sun and moon have nearly the same apparent size it is possible that there will be Total eclipse at some point in an otherwise Annular eclipse.
The total eclipse is cause buy the moon passing in front of the sun when its apparent
size is larger than the sun. Then the umbral shadow can meet the earth and you have a total eclipse. The length of any total
eclipse will vary depending on latitude Apparent size of the Sun-Moon. These are the best sort of eclipses and my advise is to just
look at your first eclipse.
Total Eclipse
Annular Eclipse
Lunar Eclipse
The Total Experience
You can tell this is going to be no normal day you can feel the tension and the excitement in the air. Then as you wait the excitement grows and then some will call FIRST CONTACT then every one will look at the sun to see first contact. There will be no loss of sunlight at this point in the eclipse. The pace will be slow to start till the sun is half covered. Now things start to happen faster and faster. The loss of light will be notable and the sky has gone a duller but is still bright. over the next 15 minutes the landscape takes on a steely grey metallic cast. as the minutes pass the pace quickens. Now with about quarter of an hour to go till totality The western sky is darker than the eastern sky regardless of where the sun is in the sky. The moon shadow is getting close You may never have seen a total eclipse before, you know that something amazing is happening. You will now see the sun is a crescent but it is still fiercely bright. The sky is now deep blue(Blue-Gray) or violet. The darkness will come to you faster and faster. When there is just a sliver of the sun left and you will see that the sun does not deliver the life giving light. Five minutes to totality you will see the darkness in the west like a storm but there will be no thunder. Then the darkness will seem to rise up and you will see the yellow twilight beneath. what you are seeing is the light on the other side of the shadow. the sun is now just a white silver and is blazing white. The darkness is now all around the sun. The minutes have become seconds. Where the sun use to be there are dots of sunlight or baily's beads flash round the edge of the sun Baily's beads are where the last sunlight shines through the lunar valleys. There is a silhouette on the opposite side to the beads. It is the other limb of the moon there is a white hallow around the dark moon now covering our star. The corona is now emerging this is the best part of any eclipse. Then the last bead of sunlight beams through the deepest lunar valley and you have the diamond ring. This last dot of sunlight fades away as if sucked into the abyss. Now the sun is now covered by the moon and you are experiencing totality. All around the jet black sun is the solar corona which is about as bright as the full moon. For the first few seconds on the eastern edge of the sun disk you will see the chromosphere which is red. Also on that side you will see prominences , they are giant clouds of hot gas in the suns lower atmosphere. They are always a surprise and vary in size and shape. They are also changing and will be different tomorrow as they were a day ago. You are standing in the shadow of the moon and its eerie darkness. The darkness is hard to explain but it is a false darkness. You can see the bright planets and stars even when close to the sun like 1998 and there is that twilight glow round the horizon. You are now at mid-point in the eclipse and the corona now shows its shape. This varies as well depending where the sun is in its 11 year cycle. But only the eye can do the corona justice. There are faint wisps and spikes only to bee seen today and not on any other day. the western horizon is brightening this is a warning that the eclipse is going to soon finish. Above you prominences appear on the western edge of the moon and the edge brightens. Then totality is over and the diamond ring signals the end of totality and you can see the shadow race away from you. There will be only one thing for you to ask "when is the next one"?
Viewing solar Eclipses
These magic events lure people from all over the world, some travelling thousands of miles to see the eclipsed sun.
What is it that draws astronomers to the far reaches of the world. Why do the media take such an interest in these
events. Why do local people who have no interest in the stars go to see this event.
First Contact
This is the point where the moon first cover the sun. All the people at the site want to be first to see
first contact. From my own experience I keep a close eye on my watch then as the time draws closer I look at
the sun to see if I can be fist to see first contact. Once that call goes out every body will see if they can see
this tiny bite out of the sun. Crescent Sun
This part holds a strange part for me it is good to watch the light fade. I always go and look for a tree
as it is possible to see hundreds of over lapping crescent suns under the tree canopy. You can see the
advance of the moon as it covers sunspots. Environment
There are a lot of changes in the local environment the sky colour changes and there are temperature changes
and the colour of the land is different and the loss of light make birds and other animals restless. There
is a strange feel to the air and there is a peace that comes over the land. In Hawaii cows laid down as if it was night
as the light levels fell. In India the birds came to roost. In Curacao there was a lot of people they just made a lot of noise.
Shadow Bands
I have never seen shadow bands at any eclipse yet. They are seen in the later partial phase as the sun becomes
a thin crescent. Only a thin shaft of sunlight passes thought the atmosphere and encounters warmer and colder air.
these two different temperature have different densities. The different densities act like a lens bending the light
and pass it around. It is this focusing and defocusing that makes stars twinkle.
The sun would twinkle to if it were a point in the sky. When it narrows to a thin silver it twinkles in the form of
bands rippling across the land.
Totality Approaching
The final one or two minutes before totality, the sun is now 99 percent eclipsed and the light is fading rapidly
it in these moment that baily's Beads the Diamond Ring and the Corona all appear. The darkness is the where the moons
shadow is coming towards you. The shadow moves east towards you but as it gets closer it accelerates. It seems like you are
being swallowed by some monster from the deep. Then as the last silver disappears there is a dark disk silhouetted
where the sun once shone and as the silver disappears it breaks into lots of little beads which last for an instant
before being replaced by another. Then only one remains the diamond ring this is a stunning sight to see the last bead
of sunlight and the dark disk surrounded by the corona. It is these last seconds that tell you why there was so much fear because of eclipses till modern times.
Totality
You are now standing in the Moons Shadow and the corona is easily visible it is hard to explain what the corona looks like but it
is a pearly glow with similar structure to Cirrus cloud, but the structure is finer than the cloud. It is hard to capture a true representation of
the corona on film as you burn the inner corona out to capture the outer corona. To get the inner corona you will not get the outer corona.
You will be able to see the prominences coming from the edge of the sun. There size and shape will vary. It is now safe to use even binoculars
on the sun when TOTALITY has arrived, These will help you see the prominences and the fine structure in the corona. Stars and planets will come out
and you may be able to see them close to the sun. Then there is that glow near the horizon. You may (I have never) see a comet close to the sun and you
maybe the first person to see it. Other people during the eclipse the thing that amuses me is the faces of the people you are near. As I said earlier
look at animals see what they are doing. The most important thing is to look at the eclipse it has taken three eclipse to do all the things here.
Totality Ends
Then that first bead of sunlight shine through and the eclipse finishes as it started with the diamond ring.
Totality ends and you then there is that joy knowing that you have seen the eclipse and you can go home with a sense of joy.
You will usually celebrate the fact that you have seen it and swap your view with others. But if you do not see the eclipse
you can say well next time.
DO NOT LOOK AT THE PARTIAL ECLIPSE WITHOUT SOLAR FILTERS PEOPLE BLINDED THEMSELVES IN SOUTH EAST ENGLAND IN 1999!!!
Other InformationThere are lots of books that you can buy that will be
very helpful. This page will be updated as time goes buy. acseal.freeserve.co.uk
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