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SOLAR and LUNAR ECLIPSES : Part 1



INTRODUCTION


All observed eclipses are caused by shadows. The Sun emits light just like any luminous source, and therefore any solid object like a planet or moon, is illuminated on one half of its ball (or sphere) and is darkened on its other half. Furthermore, the side away from the Sun also produces a long cone-like shaft of darkness or shadow, which projects at exactly 180° from the source of light. If the planet or moon intersects one of these extended shadows, this produces an eclipse. If the Sun is obscured by the Moon, for example, this creates the various types Solar Eclipses. Conversely, when the Moon passes behind the long projected shadow of the Earth, this makes the various types of Lunar Eclipses.


SOLAR ECLIPSES


One of the very first things that are truly remarkably about all solar eclipses is that the roughly ½° sized Moon and Sun happens to be about the same apparent diameter from the Earth. This planet-moon combination does not happen anywhere else in our Solar System.

Solar Eclipses are indeed rare, spectacular and awe-inspiring events, which occur in many exotic but predictable places and locations throughout the world. They often produce varied, interesting and exciting phenomena, which can direct affect wildlife, the people that observe them, and the overall appearance of the surrounding landscape. Birds, for example, will think the night has come again, and go back to roost in their nests. At mid-eclipse, for a short time, day can become like the night or even the brightening or failing twilight, where the bright stars and planets appear in the sky, but this time during the daytime.

Many superstitions once surrounded solar eclipses, and seeing one often spread fear and terror amongst many people in ancient and even some modern cultures. For example, the Chinese, once viewed solar eclipses as an immense dragon who was consuming the Sun. They once believed by making enough noise during the eclipse then the terrible dragon would be frightened away. Of course, it always did! Other cultures just hid away and shut themselves inside their own houses just before the mid-eclipse, and do not go outside again until the event is finally over. After this, they will rejoice in praise, singing in unison that the life-giving sunlight has finally returned and allow life on Earth to continue.

The Types of Solar Eclipses

There are four types of solar eclipses;

Total, Annular, Partial and Hybrid.

Total Solar Eclipses can only occur at the exact time of New Moon. All solar eclipses happen to be more rare than lunar eclipses, mainly as the apparent size of the Sun is lesser than the size of the Earths shadow in which the Moon becomes immersed.

Duration for any total eclipses is dependent on where the Moon happens to lie in its orbit and, at the time of the eclipse, its true distance from the Earth. It is also, and to a lesser extent, is dependant on the place on Earth, and the true distance between the Earth and Sun.

Considering the apparent observed size of the Moon alone, these small differences can only happen because the lunar orbit is not actually circular but is an ellipse, which moderately varies the lunar distance from the Earth between the Moons apogee (furthest away) and perigee (closest to us) — a variation of about 43,800 kilometres.

[Moon mean distance is 399,100 km, and this means that the observed apparent size or diameter of the Moon from the Earth can vary by as much as 11%.]

(a.) Total Solar Eclipses

Near perigee, when the moon is closer to the Earth, the Moons apparent diameter is larger than the Sun, so the Sun is completely obscured. Here the observer on the Earth standing where the eclipse path intersects the location, means we can observe a total solar eclipse. When both perigee and the New Moon coincide, the maximum duration of eclipse totality may last as long as seven minutes and forty seconds. Most eclipses last about two minutes or so.

(b.) Annular Solar Eclipses

Near the time of apogee, the opposite is true. Here the apparent lunar diameter is slightly smaller than the apparent diameter of the Sun. Therefore, in the middle of this kind of solar eclipse, the Sun appears like an annulus ring of bright sunlight. This produces the Annular Eclipse, whose duration may last as long as thirteen-and-a-half minutes.

(c.) Partial Solar Eclipses

A third variety is the Partial Eclipse, which can occur for observers anywhere outside the path of totality, or when the sun disk is only partial obscured anywhere on the Earth. Most solar eclipses are only partial ones, and the reason for this because not only is the lunar orbit elliptical, but lunar orbit is also titled by about 5½° to the plane that all the planets and the Sun follow — the ecliptic. This simply explains why at every successive New Moon or Full Moon, there is not some sort of observed eclipse. As said in introduction, the projected shadow can intersection with the position of the Earth or Moon, but it can also pass either above or below it. So, sometimes the Moon might passing just above or below the Earths orbit. This produces total solar eclipses in space — missing the Earth altogether. Sometimes this just produces partial eclipses place somewhere upon the Earths surface. I.e. Near the north or south poles, for example.

(d.) Hybrid Solar Eclipses

Hybrid eclipses are those between Annular and Total Solar Eclipses, and are much rarer. As the path of the eclipse across the Earths surface is on a projected sphere, this cause the size of the Moon to vary in size by half the diameter of the Earth or about 6,300 kilometres — being roughly 6300/363600 km. or 1.7%. This means if an eclipse is bordering between total and annular, that it is possible that some part of the eclipse, near mid-eclipse, can be briefly total, while at it beginning and end may appear annular.

Hybrid eclipses do show some of the typical phenomena of the total eclipse, such as Bailys beads or even the chromosphere, but do not show well the inner or corona of the Sun. Their brevity make them unpopular with observers as the location of totality is within a small region of the Earth and totality does not last very long — especially in gaining images.



TOTAL SOLAR ECLIPSES


The Path of Totality

Any total solar eclipse is really a very unique circumstance of planetary alignments. At any instant, from space each total solar eclipse appears like a round spot projected on the surface of the Earth, surrounded by a larger circular grey area. The observed central spot is the place where the Sun is seen in total eclipse on the Earth, while the grey area is in partial eclipse on the Earth.

Now as the Sun, Moon and all the planets are in constant motion, therefore the location seeing totality is also on the move, making its path move across the surface of the Earth. This is known as the path of totality. Such a path is fairly narrow, averaging about 127 kilometres across or about 1° of latitude, and this width moves along the path of the eclipse. This dark lunar shadow travels at velocities around 3,200 kilometres per hour — or four times the speed of sound. As the rounded Earth is spherical, then nearer the poles the maximum path width can extend to about 325 kilometres across. An entire eclipse length for the whole eclipse can cover perhaps between 8,000 to 10,000 kilometres across the Earths surface, though is some instances, nearer the poles this distance can be much shorter.

Frequency of Total Solar Eclipses

Occurrences of any total solar eclipse averages once every 2½ years or so. For some total solar eclipses to take place at the same location on land may take place on average once every 324 years in the northern hemisphere and 640 years in the southern hemisphere. This is because land mostly happens to lie in the northern hemisphere, while in the southern hemisphere, much of this area is just ocean. In truth, the average time for any observable solar eclipse to reoccur somewhere on the Earth is about 482 years. Sometimes two solar eclipses may occur within several years in the one location, then a third total solar eclipse will not again happen for more than one thousand years later!

Appearance of the Sun
During Total Solar Eclipses

During any total solar eclipse, we can actually see the outer atmosphere layers of the Sun. The Sun itself does not have a hard surface like the Earth, but is really a bubbling cauldron of hot gases around 6,000°C, called the photosphere — the surface seen in all images of the Sun. Like the Earth, the Sun has a lower denser atmosphere called the chromosphere, which is visible just before and after totality during total solar eclipses. This hot region is about 4,000°C appears against the lunar limb as bright luminous pink colour and is about is between ten and twenty thousand kilometres in thickness and is mainly made of hydrogen.

Beyond the chromosphere is the corona, whose true maximum high is uncertain, but can be seen as far out as 1½ times to 5 times the diameter of the Sun. The corona is a very hot gas made mostly of hydrogen and helium, and exists as a tenuous gas that exceeds several million degrees. This can be seen either by the naked-eye during totality, or in using a specially designed telescope called the coronascope. The corona appears as pearly white and is about as bright as the Full Moon, and looks like many radiating rays of light point directly away from the Sun, and is distributed along various places around the solar limb, but always tends to avoid the Suns poles. Visually the corona may extend between half and twice the diameter of the Sun, but this does vary significantly from eclipse to eclipse.

Beginning and End of Total Solar Eclipses

Near the central line of the eclipse path will see only the two important Baileys Beads, which occur when the total solar eclipse starts and finishes. This produces the renown and spectacular Diamond Ring, when the sunlight does final disappears before totality, and as the eclipse ends. Both of these contact points will are exactly 180° apart.

Baileys Beads

During both annular and total eclipses, some observers can make observations of so-called Baileys Beads. These are bright beads of light seen prior and after totality, and are formed by Sun shining through the many valleys and craters seen on the uneven Moons edge or limb. Timing these beads can give important information on the true solar diameter, which until recently times could not be measured directly. Astronomers believe that the Sun maybe gradually changing in physical size and this might produce changes in the solar energy emissions. This in turn may influence the Earths climate, and might be the reason for climate change.


Upcoming Solar Eclipses

The following tables gives a list of solar eclipses visible throughout the world. These tables give the following information;

Year and Date of the Eclipse
• Eclipse Type, being; A = Annular, T = Total, P = Partial and H = Hybrid.
• Eclipse magnitude (Eclip. Mag.) is the ratio difference in areas between the Moon and Sun. Total eclipses have values >1.0, Annular eclipses >1.0. For partial eclipses, this is the largest percentage possible of the visible disk of the Sun during the eclipse. Hybrids are generally are close to 0.0.
• Maximum Duration of the Eclipse (Central Durat.)
• Geographical Region of Eclipse Visibility

To make these tables more useable, I have coloured some of the squares to differenciate between the eclipse types. Lines coloured lime green are eclipses visible somewhere in Australia, which are again summarised in the final Table 1.4.


Table 1.1

Solar Eclipses
2008 — 2010

YEAR DD MonTypeEclip.
Mag.
Centrl
Durat.
Geographical Region of Visibility
200807 Feb A0.96502m12s Antarctica, Eastern Australia, New Zealand
[Annular: Antarctica]
200801 AugT 1.03902m27s ne N. America, Europe, Asia [Total:
n Canada, Greenland, Siberia, Mongolia, China]
200926 Jan A0.92807m54s s S. Africa, Antarctica, SE. Asia, Australia
[Annular: s Indian, Sumatra, Borneo]
200922 JulT 1.08006m39s e Asia, Pacific Ocean, Hawaii
[Total: India, Nepal, China, c Pacific]

Table 1.2

Solar Eclipses
2010 — 2020

YEAR DD MonTypeEclip.
Mag.
Centrl
Durat.
Geographical Region of Visibility
201015 JanA 0.91911m08s Africa, Asia
[Annular: c Africa, India, Malaysia, China]
201011 JulT 1.05805m20s s S. America
[Total: s Pacific, Easter Is., Chile, Argentina]
201104 JanP 0.858------ Europe, Africa, c Asia
201101 JunP 0.601------ e Asia, n N. America, Iceland
201101 JulP 0.097------s Indian Ocean
201125 Nov P0.905------ s Africa, Antarctica, Tasmania, N.Z.
201220 MayA 0.94405m46s Asia, Pacific, N. America
[Annular: China, Japan, Pacific, w U.S.]
201213 Nov T1.05004m02s Australia, N.Z., s Pacific, s S. America
[Total: n Australia, s Pacific]
201310 May A0.95406m03s Australia, N.Z., c Pacific
[Annular: n Australia, Solomon Is., c Pacific]
201303 NovH 1.01601m40s e Americas, s Europe, Africa
[Hybid: Atlantic, c Africa]
201429 Apr A0.987 ------s Indian, Australia, Antarctica
[Annular: Antarctica]
201423 OctP 0.811------ n Pacific, N. America
201520 MarT 1.04502m47s Iceland, Europe, n Africa, n Asia
[Total: n Atlantic, Faeroe Is, Svalbard]
201513 Sep P0.788------ s Africa, s Indian, Antarctica
201609 Mar T1.045 04m09se Asia, Australia, Pacific
[Total: Sumatra, Borneo, Sulawesi, Pacific]
201601 SepA 0.97403m06s Africa, Indian Ocean
[Annular: Atlantic, c Africa, Madagascar, Indian]
201726 FebA 0.99200m44s s S.Amer.,Atlantic,Africa,Antarct.
[Annular:Pacific,Chile,Argentina,Atlantic, Africa]
201721 AugT 1.03102m40s N. America, n S. America
[Total: n Pacific, U.S., s Atlantic]
201815 Feb P0.599------ Antarctica, s S. America
201813 Jul P0.336------ s Australia
201811 Aug P0.737------ n Europe, ne Asia
201906 Jan P0.715------ ne Asia, n Pacific
201902 JulT 1.04604m33s South Pacific, South America
[Total: s Pacific, Chile, Argentina]
201926 Dec A0.97003m39s Asia, Australia
[Annular: Saudi Arabia, India, Sumatra, Borneo]

Table 1.3

Solar Eclipses
2020 - 2030

YEAR DD MonTypeEclip.
Mag.
Centrl
Durat.
Geographical Region of Visibility
202021 JunA 0.99400m38s Africa, se Europe, Asia
[Annular: c.Africa, s.Asia, China, Pacific]
202014 DecT 1.02502m10s Pacific, s S.America, Antarctica
[Total: s Pacific, Chile, Argentina, s Atlantic]
202110 JunA 0.94303m51s n N. America, Europe, Asia
[Annular: n.Canada, Greenland, Russia]
202104 DecT 1.03701m54s Antarctica, S. Africa, s Atlantic
[Total: Antarctca]
202230 Apr P0.640------ se Pacific, s S. America
202225 Oct P0.862------ Europe, ne Africa, Mid East, w Asia
202320 Apr H1.01301m16s e Asia, E.Indies, Aust., Philippines, N.Z.
[Hybrid: Indonesia, Aust., Papua New Guinea]
202314 OctA 0.95205m17s N. America, C. America, S. America
[Annular: w US, C. America, Columbia, Brazil]
202408 AprT 1.05704m28s N. America, C. America
[Total: Mexico, c US, e Canada]
202402 OctA 0.93307m25s Pacific, s S. America
[Annular: s Chile, s Argentina]
202529 Mar P0.938------ nw Africa, Europe, n Russia
202521 Sep P0.855------ s Pacific, N.Z., Antarctica
202617 FebA 0.96302m20s s Argentina & Chile, s.Africa, Antarctica
[Annular: Antarctica]
202612 AugT 1.03902m18s n N. America, w Africa, Europe
[Total: Arctic, Greenland, Iceland, Spain]
202706 FebA 0.92807m51s S. America, Antarctica, w.& s.Africa
[Annular: Chile, Argentina, Atlantic]
202702 AugT 1.07906m23s Africa,Europe,Mid East, W&S.Asia
[Total:Morocco,Spain,Algeria,Libya,Egypt,
Saudi Arabia,Yemen,Somalia]
202826 JanA 0.92110m27s e N.America, C.& S.America, w.Europe, nw.Africa
[Annular: Ecuador, Peru, Brazil, Suriname,
Spain, Portugal]
202822 Jul T1.05605m10s SE Asia, E. Indies, Australia, N.Z.
[Total: Australia, N.Z.]
202914 Jan P0.871------ N. America, C. America
202912 Jun P0.458------ Arctic, Scandanavia, Alaska, n Asia, n Canada
202911 Jul P0.230------ s Chile, s Argentina
202905 Dec P0.891------ s Argentina, s Chile, Antarctica
203001 JunA 0.94405m21s Europe, n Africa, Mid-East, Asia, Arctic, Alaska
[Annular: Algeria,Tunesia,Greece,Turkey,Russia,
n.China,Japan]
203025 Nov T1.04703m44s s Africa, s Indian Oc., E.Indies, Aust., Antarctica
[Total: Botswana, S.Africa, Aust.]

Table 1.4

Upcoming Solar Eclipses Near Australia
2008 - 2030

2008 - 2030
DD Mon Year Type Eclip.
Mag.
Central
Duration
07th Feb 2008Annular0.96502m 12s
26th Jan 2009Annular0.92807m 54s
25th Nov 2011Partial0.905--
13th Nov 2012Total1.05004m 02s
10th May 2013Annular0.95406m 03s
29th Apr 2014Annular0.987--
09th Mar 2016Total1.04504m 09s
13th July 2018Partial0.336--
26th Dec 2019Annular0.97003m 39s
20th Apr 2023Hybrid1.01301m 16s
22th July 2028Total1.05605m 10s
25th Nov 2030Total1.04703m 44s
* See


I M P O R T A N T

When Observing the Sun

The Sun is the brightest object in the sky, and produces so much light and heat that it can be easily felt on the skin. However, under no circumstances should the Sun be observed directly with the eyes and NEVER directly with telescopes or binoculars. You can only safely look at total solar eclipses but only when the Moon completely obscures Sun. You must look away as the diamond begins or ends. Older children should always be prewarned beforehand and be made to listen to responsible adults when they should look away. Check they do so. Younger children are always better kept inside the house if they do not understand what is happening.

!!! W A R N I N G !!!

Using any telescope, the Sun should ONLY be observed by projecting the image onto a white screen or card. (Even this should be for short periods)
Direct viewing of the Sun, by either eye or any other optical equipment, is VERY DANGEROUS without proper eye protection. Otherwise, TOTAL BLINDNESS WILL RESULT, and even glancing will blind you in less than a ten-thousandth of a second.
If your telescope has something called a SUN FILTER — NEVER USE IT !! If this filter were to crack while you are observing the Sun, INSTANT blindness is the only possible outcome.

!!! W A R N I N G !!!

(NOTE : PLEASE READ THE DISCLAIMER BELOW.)


Important Disclaimer

The user applying this data for any purpose forgoes any liability against the author. None of the information should be used for either legal or medical purposes. Although the data is accurate as possible some errors might be present. The onus of its use is place solely with the user. Those not heading the given important warnings on this page do so at their own risk.


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Last Update : 26th November 2012

Southern Astronomical Delights © (2012)

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