A Presentation to Astronomy Ireland By: David Grennan, 27 th February 2006

A Presentation to Astronomy IrelandBy: David Grennan, 27th February 2006

Solar Eclipses - Past, Present, and Future.

Eclipse Mythology

Chinese, Hindu, Egyptian, Impact on modern dayscience and religion.

Mechanics of Solar Eclipses

Why eclipses occur.Types of Eclipse.Phases of an eclipse.Shadows Bailys Beads.Diamond Ring.TemperatureCorona.Prominences.

Solar Eclipses - Past, Present, and Future.

Safely Viewing Eclipses

Eclipse, March 29, 2006 a guide.

Using computer simulations

Eclipse from Ireland.Eclipse from Turkey.Eclipse from SpaceFuture Eclipses

Important Eclipses present – 2030The 'almost' total eclipse of 2015 from Ireland.

Eclipse Loreand Mythology

"Nothing there is beyond hope, nothing that can be sworn impossible,nothing wonderful, since Zeus, father of the Olympians,made night from mid-day, hiding the light of the shining Sun,and sore fear came upon men." Archilochus (c.710 - 676 BC)

Eclipse Lore and Mythology

Our ancestors saw eclipses as evil omens, often as portentsof some catastrophic event or a sign from their deities.

The earliest recorded eclipse was in China on October 22, 2134 BC. The two court astrologers to theEmporer lost their heads because, they had failed to predict it

The Babylonians were the first to calculate the regularintervals at which eclipses occur.Thales of Miletus predicted a solar eclipse that markedthe beginning of the Greek scientific/philosophic era.

Eclipse Lore and Mythology

Word eclipse comes from a Greek word, “ekleipsis”meaning abandonment.

There is a story that suggests Christopher Columbus used hisKnowledge of an upcoming lunar eclipse to great effect.

Ancient China

People of ancient China were convinced that eclipsesOccurred because a great dragon (or toad, or dog) wasDevouring the Sun.

They made load noises, banged implements etc to scareAway the dragon.

As total eclipses can only last a maximum of 7 ½ minutesThere raucous behaviour always had the desired effect.

Ancient China

Han Dynasty (206 BC - 220 AD)

Hindu Folklore

According to Hindu mythology, the eclipse representsthe demons Rahu and Keta locked in celestial combat andeating the Sun.

Hindu Folklore

The Gods were drinking the elixir of immortality.The demon Rahu slipped into their midst and stole a sip.Surya (the sun) and Soma (the moon) reported the incidentto the great deity Vishnu.

Vishnu promptly sought out the impudent Rahuand lopped off his head.But having become deathless, Rahu survived and to this dayseeks revenge on the tattletales by devouring them.

Ancient Egypt

The egyptian word for eclipse is ‘Akhet’

King Akhenaten (1356-1338 BC) built his capital accordingto the totality path of the solar eclipse of 08/15/-1351.The Pharaoh named his new residence 'Akhet Aten'.The name of the city means: 'The Eclipse of Aten'.

The name of the Giza Sphinx was 'Hor in the Akhet‘

Many different ancient egyptian sun cults saw eclipsesDifferently. Many refer to a serpent eating the Sun God.Most however refer to a great hawk stealing RA’s glory.

Eclipses and Religion

Many hindus to this day immerse themselves in holy riversAnd lakes during solar eclipses.Working during eclipses is considered bad luck.

Muslim tradition holds that the prophet Mohammed,the founder of Islam, prayed for the duration of an eclipse.

Senior muslim clerics issued an edict forbidding people tolook at the Sun directly because it transgresses Islamic lawto harm oneself.

Druids believe eclipse represents man and woman together.

Eclipses and Religion

Luke 23:44-48 “And it was about the sixth hour, and therewas a darkness over all the earth until the ninth hour. And the sun was darkened, and the veil of the templewas rent in the midst.”

Some suggest a solar eclipse as an explaination forThe ‘darkness’ however the facts don’t lend credance.

Mechanics of Solar Eclipses

Solar eclipse of11 Aug 1999From MIRSpacestation.

Mechanics of Solar Eclipses

Todo insert flash file.

PartialEclipse

Annular Eclipse

Total EclipseAlthough a total eclipse refers to a specific event, the events leadingUp to ‘totality’ and following it also hold much interest.

Partial PhaseShadowsBailys BeadsDiamond RingTotality

Partial Phase

During the partial phase there are many interesting things to note.

First Contact.Eclipse increasing in magnitude.Temperature.Increasing DarknessShadow BandsCrescent ShadowsCreatures settling believing night is imminentMoons shadow racing from the west(ish).Bailys BeadsDiamond Ring

First Contact.The moment when the western limb of the Moon contacts theEastern limb of the Sun.

First contact is not directlyVisible, however very shortlyAfterwards a little ‘bite’ isTaken from the Sun.

TemperatureAs the eclipse increases in magnitude, the amount of warmingSunlight reaching us falls.

As the eclipse reaches 70-80% you will begin to feel a noticeableCoolness as if night were coming.

Increasing DarknessWith the decrease in the area of Sun presented to usAmbient light levels fall.

Most noticeable in the latter stages of the eclipse.

Video from west Africa showing this dramatically.

Shadow BandsCaused by distortions in the Earth’s atmosphere and the partiallyEclipsed Sun.

Best seen on a pale colouredWall or concrete pavement.

Crescent ShadowsNote shadows cast by irregularly shaped objects such as leavesFrom trees.

Crescent Shadows

Bailys Beads.

At this point the only sunlight reaching us is through the undulatingValleys on the Moons limb.

Bailys Beads.

Diamond Ring

The chromosphere is visible and the ‘Corona’ is becoming visible.The very last of ‘Bailys Beads’ is also visible.Totality is now imminent!!!!!!

Totality!!!!

Totality!!!!

The Hybrid Eclipse.

The official explaination!

“A hybrid eclipse is a unique type of central eclipse where partsof the path are annular while other parts are total.This duality comes about when the vertex of the Moon's umbralshadow pierces Earth's surface at some points, but falls shortof the planet along other portions of the eclipse path.The curvature of Earth's surface brings some geographic locationsalong the path into the umbra while other positions are more distantand enter the antumbral rather than umbral shadow.”

Fred Espenak

The Hybrid Eclipse.In practice!

SafelyViewingEclipses

Eclipse Safety

Directly looking at the Sun,even for a short time,CAN PERMANENTLYDAMAGE YOU EYESIGHT

Eclipse Safety

Approved solar filter materialShould be used to cover yourEquipment and your eyesAT ALL TIMES.

Sunglasses

You should choose sunglasses that:

•reduce glare•filter out 99-100% of UV rays•protect your eyes•are comfortable to wear•do not distort colors.

Source: Prevent Blindness America.

How to use Filter Material

How to use Filter Material

How to use Filter Material

Eclipse of March 29th 2006

.

We will use computer simulations to look at thisEclipse from different vantage points

Animations created with Starry Night Pro PlusSoftware.

Important Solar Eclipses

Present - 2030