Cycles of the Moon

The Moon inspires poets, painters, composers, song writers - all of us. Why?

Daily Motion of the Moon

You may have noticed that the Moon moves a considerable amount from night to night. This is not surprising when you consider that a month is the amount of time required for the Moon to complete an orbit around the Earth so, by simple math the Moon moves approximately 360/30 = 12 degrees per day. If you use your "mind's eye" you will also likely recall that the Moon seems to "rise later" each day - this means that the Moon's motion is a slow, eastward drift with respect to the background stars. Figure 3.13 shows the Moon drifting eastward acrsoss the Pleiades ("Seven Sisters") on the evening of March 3, 2009.

This eastward drift is due to the Moon's orbital motion around the Earth and amounts to approximately 0.5 degrees per hour. Since the moon itself is about 0.5 degrees in diameter in the sky this means that the moon drifts its own diameter eastward in one hour. Different Kinds of Months A month is "not just a month" - it depends on how you define the term. As you have begun to appreciate, in astronomy terms must be defined carefully. Consider the following ways in which we can refer to a "month": Sidereal Month This is the time required for the moon to return to the same position relative to the background stars. 1 sidereal month = 27.32166 days

Figure 3.13 The eastward drift of the Moon through the Pleaides cluster on the evening of March 3, 2009.

• Nodical (or Draconic) Month This is the time required to pass through the nodes or intersections between the Moon's orbit and the Earth-Sun orbital plane. The line of nodes which is formed by the intersection of these two planes is a very important idea when considering when eclipses can occur. 1 Nodical month = 27.21222 days.
• Synodic Month This is the time required for the Moon to return to the same orientation with respect to the Sun. This is closest to our colloquial use of the tem month and is the month used to determine lunar phases. 1 Synodic month = 29.53059 days.

Example 3.4 Explain what the difference is between a sideral month and a synodic month and why the synodic month is more than two days longer?

Solution: The sidereal month is the time required for the Moon to orbit through 360 degrees (1 revolution) with respect to the background stars. The synodical month is the time needed for the moon to return to the same phase (orientation relative to the sun). But - the Sun is also drifting eastward so it takes an addition 2 days for the Moon to "catch up" to the sun. Teh drift in the Sun's position is due to Earth's motion around the sun.

Lunar Phases

The monthly progression from new Moon to full and then to new Moon is the most easily and widely recognized of the motions in the heavens. How can we explain the phenomenon of lunar phases? To help, use your "mind's eye" for a moment to consider the following: where is the Moon in relation to the Sun when the Moon is full? where is the Moon in relation to the Sun when the Moon is new? where is the Moon in relation to the Sun when the Moon is in either first or third quarter phase?

Figure 3.14 Animation showing the Moon in its phases.

Also, some more subtle questions are:

• what is the shape of the line dividing light from dark (the terminator) on the lunar surface?
• in what direction does the Moon appear to move during the night?
• in what direction does the Moon appear to move from night to night?

The answer to all of the above can be nicely found by using Stellarium or Celestia.

Example 3.5 You notice the first quarter moon in the southern sky, close to the meridian (due south). What time of day is it?

Solution: It must be very close to sunset. In order to see a quarter phase the Sun must be at 90 degrees to the Moon. Since it is first quarter the moon has passed through the New phase and is moving eastward in the sky - this means the sun must be setting.

Ever wonder where the phrase "once in a blue Moon" comes from? There are at least two explanations and are probably - taken together - a good explanation of the term. First, the phrase connotes something unusual or rare. This leads to the first explanation:

• Blue Moons are the rare occurrence of two full months within the same month. The following table lists a few of the blue Moons that you may be able to see:

Month	Days	Year
December	2, 31	2009
August	2, 31	2010
July	2, 31	2015
March	2, 31	2018
Table 3.3 Some "blue Moon" months

• A second explanation is that under very rare atmospheric conditions complex scattering and absorption of Moonlight by dust in the Earth's atmosphere can produce a very distinctly blue colored Moon. There are many reports of such occurrences.

Solar and Lunar Eclipses That Changed History

Eclipses are dramatic events - no wonder that they have a prominent place in historical records and have commanded the attention, awe and curiosity of people throughout the ages. The blood red to coppery hues of a lunar eclipse occur because as the moon slips into the shadow cast by the Earth the only light that illuminates the Moon has passed through Earth's atmosphere. This light is "redenned" - the same way that the sky is a deep red colour at sunset. So - the moon is illuminated with "sunset" light. Before we look at the conditions that lead to both Lunar and Solar Eclipse let's fist look at some examples of eclipses and how they have influenced history.

Figure 3.16 January 2000 - first Lunar Eclipse in the new Millenium

Example 3.6 Sketch the Sun-Earth-Moon orientation needed to produce an eclipse such as the one shown in Figure 3.16.

Solution: The Moon must be in a Full phase. If you have a copy of Celestia you can reproduce the eclipse geometry as shown in the video clip below.

What would this look like from the Moon? Click on the icon to see video clip of this produced with Stellarium

Simple sketch of the geometry of a total lunar eclipse.	The Moon slipping behind the Earth. The yellow dot on the Earth is pointing directly toward the Sun.

Some Significant Lunar Eclipses

• 413 BC A lunar eclipse is seen as a bad omen, the Athenian leader Demosthenesl delays deployment of his navy for an entire lunar month. The delay proved costly giving the Syracuse navy time to prepare. The Athenian fleet was destroyed. A crucial event in the Peloponnesian War.
• 1453 the Turks held Constantinople under siege. The Christians within the walls of the city were demoralized. On May 22 a total lunar eclipse was seen as a sign - not a good one! The city fell six days later.
• Christopher Columbus and his crew have "worn out their welcome"! They were running low on supplies and the native chiefs were making ominous threats. Columbus discovered in his almanac that a lunar eclipse was to occur on February 29, 1504. Three days prior to the eclipse he warned the chiefs that "his God" was displeased with them and that he would demonstrate this by a clear sign. The eclipse trick worked! The chiefs once again revered Columbus and began to supply his ships.

Figure 3.17Total lunar eclipse on the night of January 20-21, 2000. Image is a composite of photos taken using a 600 mm lens at f/6 with exposures from 1/60 s to 1 minute. Image taken at The King's University College Observatory.

Other Recent Lunar Eclipses...

Lunar eclipses are a relatively frequent event and chances are very good that you have seen at least one eclipse. One of the reasons that the lunar eclipse is more frequently seen than the solar eclipse is that the lunar eclipse can be seen anywhere on the globe where the Moon is visible. For a solar eclipse to be visible, however, the observer must be situated along a very narrow path cast by the shadow of the Moon on the Earth.

Figure 3.19 October 2004 Lunar Eclipse.

Figure 3.20 September 27, 2015 "Super-Moon" Lunar Eclipse (click for larger view)

Example 3.5 What phase must the Moon be in for a lunar eclipse to occur?

Solution: The Moon must be full - it must be situated opposite the sun in our sky if it is to be able to slip through the shadow cast by the Earth.

Some Significant Solar Eclipses

• During the 18th and 19th centuries white Europeans invaded North America. Native cultures were being systematically destroyed. The Shawnee chief Tecumseh realized that the only hope for the various tribes in eastern and central North America was to join together. He was assisted by his brother - Tenskwatawa - a "prophet" who called for a rejection of the "white ways" and a return to traditional values. The governor of the Indiana territories, William Harrison, attempted to discredit both Tecumseh and Tenskwatawa. He chided Tenskwatawa to "show him a sign". Tenskwatawa was ready for Tecumseh had learned from explorers that a total solar eclipse was to occur on June 16, 1806. Tenskwatawa and Tecumseh assembled a great crowd in Greenville, Ohio to witness the Great Spirit's Displeasure. During the height of the eclipse Tecumseh ordered the Great Spirit to release the Sun! Tecumseh's fame spread quickly and he was able to unite - for a time - the tribes of the area.
• February 12, 1831 the black slave preacher Nat Turner witnessed a total solar eclipse. It was a vision from God of a "black angel" overtaking a "white angel". The fomenting slave rebellion gained impetus and on August 13 Turner saw another spectacle - a naked eye Sunspot. The rebellion began on August 21 but was quickly crushed and Turner hanged.
• In 1915 Albert Einstein made a dramatic prediction concerning the effect that gravity has on space. According to Einstein, gravity curves space. For example, light from a star should be deflected inward slightly as it passes by the Sun. To test this idea the eclipse of May 29, 1919 was observed. In close agreement to Einstein's prediction starlight was indeed deflected as it passed the Sun. When asked what he would think should his prediction had proved wrong Einstein responded that he would have felt sorry for the dear Lord - the theory is so beautiful!

Some Examples: Solar Eclipse Movies and Images

Annular Eclipses The Moon's orbit around the Earth and Earth's orbit around the Sun are not perfectly circular but slightly elliptical. This means the apparent size of both the Sun and Moon vary in our sky. Ocassionally during an eclipse the Moon's apparent size is too small to completely block the Sun. When this happens an annular eclipse results. Figure 3.20 shows such a case.
	Figure 3.21 Video clip showing an annular eclipse
Path of Totality During an eclipse the Moon's shadow traces out a narrow curved path on the Earth beneath. This is called the path of totality and you must be situated along this path in order to see the eclipse as total or 100%. Figure 3.21 shows the shadow moving across the Pacific Ocean ascaptured by an orbiting satellite July 1991.
	Figure 3.22 A satellite view of the shadow of the 1991 Baha, California eclipse
The Diamond Ring Effect One of the most enthralling sights during a total solar eclipse is the "diamond ring" effect - so called because for a few seconds the Moon looks like a magnificent diamond ring. This happens when shafts of Sunlight pass through lunar valleys on the edge of the Sun either just as the eclipse begins or ends.	>
	Figure 3.23 A total eclipse showing corona and diamond ring effect
Antarctica 2003 The first total solar eclipse ever observed from Antarctica.	>
	Figure 3.24 First ever total eclipse viewed from Antarctica

So What's So Special About Eclipses?

Question

• line of nodes (the intersection of the Moon-Earth and Earth-Sun orbital planes) points toward the Sun (the Sun must apear to be at the node)
• the Moon is on the line of nodes

In the figure on the right, neither of these conditions is met. The Moon's shadow will miss the Earth and a solar eclipse is not possible. The Moon is, however, in the new phase. Click here if you would like to run video illustrating this.
	Figure 3.26 Non-eclipse alignment at New Moon.
This time, however, both conditions are met and a solar eclipse results. Click here if you would like to run video illustrating this.
	Figure 3.27 Moon is new and on line of nodes which is pointing at the sun - a solar eclipse will occur.

Just When I Started to Understand It!!

Well, there is one more little complication! As the Earth moves around the Sun the line of nodes is rotating. This is mostly due to the simple change in the position of the Sun during the year. This means that there are only two periods during the year - called eclipse seasons - when the line of nodes is pointing toward the Sun. It is only during these periods that an eclipse is possible. If the Moon is new during the eclipse season a solar eclipse will result. (Need it be total?)

Actually - there is one more Complication!

Remember precession? The Moon's orbit is slowly precessing or turning westward by about 19.4 degrees per year. After 18 years the line of nodes has returned to its previous orientation. A yearly consequence of this precession is that eclipse seasons begin about 19 days earlier each succeeding year.

Example 3.6 Why is a solar eclipse usually either preceeded or followed by a lunar eclipse?

Solution: In the two weeks of time that separate the New and Full phases the Moon will still be close enough to the line of nodes for at least a partial eclipse to occur.

Putting this all Together ...

The Facts:

• Moon's orbit is tipped at about 5 degrees with respect to the plane of the Earth's orbit
• Earth - Sun distance varies by about 2% during the year

Basic Conditions for an Eclipse:

• Sun is along the direction of a node
• Moon is one of the nodes

Other Factors Affecting an Eclipse:

• distance of Moon wrt Earth
• distance Earth wrt Sun

Eclipse Seasons

The Saros As early as the 6th century BC the Chaldeans had noticed a pattern when lunar eclipses occured. Roughly every 18 years the Sun, Earth and Moon are in a similar alignment and will produce an eclipse very similar to its predecessor 18 years earlier with the exception that it ouccurs westward (by about 1/3 the way around the globe). This patten is called "Saros" which is Greek for repetition One Saros = 6585.32 days or 18 years, 11.33 days or 223 lunar months - the number arises because that is the number of whole months required for all the cycles of Sun wrt lunar nodes repeats. The eclipse seasons repeat with a period of 346.62 days = 1 eclipse year. Figure 3.27 illustrates the Saros.

Figure 3.28 The Saros for eclipses (both lunar and solar) between 1995 and 2025

The red circles indicate solar eclipses while the gray circles are lunar eclipses. Why are the bands in this graph separated by 9 years rather than 18? Also, note that a complete eclipse cycle is 18 years 11 and 1/3 days. Thus, if an eclipse occurs today it will take another 18 years, 11 and 1/3 days before this particular node and Moon-Sun orientation reoccurs. Another eclipse occurs but 1/3 the way around the world (west of the previous eclipse of that cycle).
 

Future Eclipses - Book Your Cruise Now! (Complete Table to 2100)

Date	Saros	Type	Central duration (min:s)	Path width		Geographical area
				km	mi
August 21, 2017	145	Total	2:40	115	71	Total: Oregon, Idaho, Wyoming, Nebraska, northeastern Kansas, Missouri, Southern Illinois, Western Kentucky, Tennessee, Southwestern North Carolina, northeastern Georgia, South Carolina, Southwest Virginia Partial: North America, Hawaii, Greenland, Iceland, British Isles, Portugal, Central America, Caribbean, northern South America, Chukchi Peninsula
February 15, 2018	150	Partial	—	—		Partial: Antarctica, Southern South America
July 13, 2018	117	Partial	—	—		Partial: South Australia, Victoria, Tasmania, Indian Ocean, Budd Coast
August 11, 2018	155	Partial	—	—		Partial: Northeastern Canada, Greenland, Iceland, Arctic Ocean, Scandinavia, northern British Isles, Russia, northern Asia
January 6, 2019	122	Partial	—	—		Partial: Northeastern Asia, Southwestern Alaska, Aleutian Islands
July 2, 2019	127	Total	4:33	201	125	Total: Pitcairn Islands, central Argentina and Chile, Tuamotu Archipelago Partial: South America, Easter Island, Galapagos Islands, Southern Central America, Polynesia
December 26, 2019	132	Annular	3:40	118	73	Annular: Saudi Arabia, Bahrain, Qatar, United Arab Emirates, Oman, Lakshadweep, Southern India, Sri Lanka, northern Sumatra, southern Malaysia, Singapore, Borneo, central Indonesia, Palau, Micronesia, Guam Partial: Asia, Western Melanesia, northwestern Australia, Middle East, East Africa
June 21, 2020	137	Annular	0:38	21	13	Annular: Democratic Republic of the Congo, Sudan, Ethiopia, Eritrea, Yemen, Empty Quarter, Oman, southern Pakistan, northern India, New Delhi, Tibet, southern China, Chongqing, Taiwan Partial: Asia, Southeastern Europe, Africa, Middle East, West Melanesia, Western Australia, Northern Territory, Cape York Peninsula
December 14, 2020	142	Total	2:10	90	56	Total: Southern Chile and Argentina, Kiribati, Polynesia Partial: Central and Southern South America, Southwest Africa, Antarctic Peninsula, Ellsworth Land, Western Queen Maud Land
June 10, 2021	147	Annular	3:51	527	327	Annular: Northern Canada, Greenland, Russia Partial: Northern North America, Europe, Asia
December 4, 2021	152	Total	1:54	419	260	Total: Antarctica Partial: South Africa, South Atlantic
April 30, 2022	119	Partial	—	—		Partial: Southeast Pacific, Southern South America
October 25, 2022	124	Partial	—	—		Partial: Europe, northeast Africa, Mid East, West Asia
April 20, 2023	129	Hybrid	1:16	49	30	Hybrid: Indonesia, Australia, Papua New Guinea Partial: Southeast Asia, East Indies, Philippines, New Zealand
October 14, 2023	134	Annular	5:17	187	116	Annular: Western United States, Central America, Colombia, Brazil Partial: North America, Central America, South America
April 8, 2024	139	Total	4:28	198	123	Total: Mexico, central and northeastern United States, East Canada Partial: North America, Central America
October 2, 2024	144	Annular	7:25	266	165	Annular: Southern Chile, Southern Argentina Partial: Pacific, Southern South America
March 29, 2025	149	Partial	—	—		Partial: Northwest Africa, Europe, northern Russia
September 21, 2025	154	Partial	—	—		Partial: South Pacific, New Zealand, Antarctica
February 17, 2026	121	Annular	2:20	616	383	Annular: Antarctica Partial: South Argentina, Chile, South Africa, Antarctica
August 12, 2026	126	Total	2:18	294	183	Total: Arctic, Greenland, Iceland, Spain, Northeastern Portugal Partial: Northern North America, Western Africa, Europe
February 6, 2027	131	Annular	7:51	282	175	Annular: Chile, Argentina, Atlantic Partial: South America, Antarctica, West and South Africa
August 2, 2027	136	Total	6:23	258	160	Total: Morocco, Spain, Algeria, Tunisia, Libya, Egypt, Saudi Arabia, Yemen, Somalia Partial: Africa, Europe, Mid East, West and South Asia
January 26, 2028	141	Annular	10:27	323	201	Annular: Ecuador, Peru, Brazil, Suriname, Spain, Portugal Partial: Eastern North America, Central and South America, Western Europe, northwest Africa
July 22, 2028	146	Total	5:10	230	140	Total: Australia, New Zealand Partial: Southeast Asia, East Indies
January 14, 2029	151	Partial	—	—		Partial: North America, Central America
June 12, 2029	118	Partial	—	—		Partial: Arctic, Scandinavia, Alaska, northern Asia, northern Canada
July 11, 2029	156	Partial	—	—		Partial: Southern Chile, Southern Argentina
December 5, 2029	123	Partial	—	—		Partial: Southern Argentina, Southern Chile, Antarctica
June 1, 2030	128	Annular	5:21	250	160	Annular: Algeria, Tunisia, Greece, Turkey, Russia, northern China, Japan Partial: Europe, Northern Africa, Mid East, Asia, Arctic, Alaska
November 25, 2030	133	Total	3:44	169	105	Total: Botswana, South Africa, Australia Partial: South Africa, Southern Indian Ocean, East Indies, Australia, Antarctica
May 21, 2031	138	Annular	5:26	152	94	Annular: Angola, Republic of the Congo, Zambia, Tanzania, south Indian Ocean, Malaysia, Indonesia Partial: Africa, south Asia, East Indies, Australia
November 14, 2031	143	Hybrid	1:08	38	24	Hybrid: Pacific, Panama Partial: south United States, Central America, northwest South America
May 9, 2032	148	Annular	0:22	44	27	Annular: south Atlantic Partial: south South America, South Africa
November 3, 2032	153	Partial	—	—		Partial: Asia
March 30, 2033	120	Total	2:37	781	485	Total: east Russia, Alaska Partial: North America
September 23, 2033	125	Partial	—	—		Partial: south South America, Antarctica
March 20, 2034	130	Total	4:09	159	99	Total: Nigeria, Cameroon, Chad, Sudan, Egypt, Saudi Arabia, Iran, Afghanistan, Pakistan, India, China Partial: Africa, Europe, west Asia
September 12, 2034	135	Annular	2:58	102	63	Annular: Chile, Bolivia, Argentina, Paraguay, Brazil Partial: Central America, South America
March 9, 2035	140	Annular	0:48	31	19	Annular: New Zealand, Pacific Partial: Australia, Mexico, Antarctica
September 2, 2035	145	Total	2:54	116	72	Total: China, Korea, Japan, Pacific Partial: east Asia, Pacific
February 27, 2036	150	Partial	—	—		Partial: Antarctica, south Australia, New Zealand
July 23, 2036	117	Partial	—	—		Partial: south Atlantic
August 21, 2036	155	Partial	—	—		Partial: Alaska, Canada, Arctic, west Europe, northwest Africa
January 16, 2037	122	Partial	—	—		Partial: north Africa, Europe, Mid East, west Asia
July 13, 2037	127	Total	3:58	201	125	Total: Australia, New Zealand Partial: East Indies, Australia, Pacific
January 5, 2038	132	Annular	3:18	107	66	Annular: Cuba, Dominican Republic, Cote d'Ivoire, Ghana, Niger, Chad, Egypt Partial: east North America, north South America, Atlantic, Africa, Europe
July 2, 2038	137	Annular	1:00	31	19	Annular: Colombia, Venezuela, Mauritania, Morocco, Mali, Niger, Chad, Sudan, Ethiopia, Kenya Partial: North and Central America, South America, Africa, Europe, Mid East
December 26, 2038	142	Total	2:18	95	59	Total: Australia, New Zealand, south Pacific Partial: southeast Asia, East Indies, Australia, New Zealand, south Pacific, Antarctica
June 21, 2039	147	Annular	4:05	365	227	Annular: Alaska, north Canada, Norway, Sweden, Finland, Estonia, Russia Partial: North America, west Europe
December 15, 2039	152	Total	1:51	380	240	Total: Antarctica Partial: south South America
May 11, 2040	119	Partial	—	—		Partial: Australia, New Zealand, Antarctica
November 4, 2040	124	Partial	—	—		Partial: North and Central America
April 30, 2041	129	Total	1:51	72	45	Total: Angola, Republic of the Congo, Uganda, Kenya, Somalia Partial: Brazil, Africa, Mid East
October 25, 2041	134	Annular	6:07	213	132	Annular: Mongolia, China, Korea, Japan, Pacific Partial: east Asia, Pacific
April 20, 2042	139	Total	4:51	210	130	Total: Malaysia, Indonesia, Philippines, north Pacific Partial: east and southeast Asia, Australia, Pacific
October 14, 2042	144	Annular	7:44	273	170	Annular: Thailand, Malaysia, Indonesia, Australia, New Zealand Partial: south-east Asia, East Indies, south Pacific, Antarctica
April 9, 2043	149	Total (non-central)	—	—		Total: northeast Russia Partial: north North America, northeast Asia
October 3, 2043	154	Annular (non-central)	—	—		Annular: south Indian Ocean Partial: Antarctica, southwest Australia, Indian Ocean
February 28, 2044	121	Annular	2:27	—		Annular: south Atlantic Partial: Antarctica, South America
August 23, 2044	126	Total	2:04	453	281	Total: Greenland; Canada's Northwest Territories and Nunavut, Alberta, southwestern Saskatchewan; Montana, North Dakota Partial: north Asia, western North America, Greenland
February 16, 2045	131	Annular	7:47	281	175	Annular: New Zealand, Pacific Partial: Australia, Hawaii
August 12, 2045	136	Total	6:06	256	159	Total: south United States, Haiti, Dominican Republic, Venezuela, Guyana, French Guiana, Suriname, Brazil Partial: North, Central and South America, western Africa
February 5, 2046	141	Annular	9:42	310	190	Annular: Papua New Guinea, Hawaii, California, Oregon, Idaho Partial: Australia, western United States
August 2, 2046	146	Total	4:51	206	128	Total: Brazil, Angola, east Namibia, Botswana, South Africa, Swaziland, south Mozambique Partial: Africa
January 26, 2047	151	Partial	—	—		Partial: east Asia, Alaska
June 23, 2047	118	Partial	—	—		Partial: north Canada, Greenland, northeast Asia
July 22, 2047	156	Partial	—	—		Partial: southeast Australia, New Zealand
December 16, 2047	123	Partial	—	—		Partial: Antarctica, south Chile, south Argentina
June 11, 2048	128	Annular	4:58	272	169	Annular: midwest United States, Quebec, Ontario, Greenland, Iceland, Norway, Sweden, Russia, Afghanistan Partial: North America, Caribbean, north Africa, Europe, west Asia
December 5, 2048	133	Total	3:28	160	99	Total: Chile, Argentina, Namibia, Botswana Partial: south South America, southwest Africa
May 31, 2049	138	Annular	4:45	134	83	Annular: Peru, Ecuador, Colombia, Venezuela, Guyana, Senegal, Mali, Burkina Faso, Ghana, Nigeria Partial: southeast United States, Central America, South America, Africa, south Europe
November 25, 2049	143	Hybrid	0:38	21	13	Hybrid: Saudi Arabia, Yemen, Malaysia, Indonesia Partial: east Africa, south Asia, East Indies, Australia
May 20, 2050	148	Hybrid	0:21	27	17	Hybrid: south Pacific Partial: New Zealand, southwest South America
November 14, 2050	153	Partial	—	—		Partial: northeast United States, east Canada, north Africa, Europe
April 11, 2051	120	Partial	—	—		Partial: Asia, Alaska, Canada, Greenland
October 4, 2051	125	Partial	—	—		Partial: Antarctica, Australia, New Zealand
March 30, 2052	130	Total	4:08	164	102	Total: central Pacific, Mexico, United States, central Atlantic Partial: Central and North America, north South America
September 22, 2052	135	Annular	2:51	106	66	Annular: Australia, south Pacific Partial: New Zealand, Antarctica, West Indies
March 20, 2053	140	Annular	0:50	31	19	Annular: central Indian Ocean, Indonesia Partial: Africa, Indies, Australia, Antarctica

 

Example 3.7 On August 21, 2017 a total solar eclipse occured in the the Western US to the Carolinas. This was a remarkable eclipse because the previous eclipse in the same cycle (Saros) also passed through a very populated area. When did the previous eclipse occur and when will the next eclipse in the same Saros occur?

Solution: The Saros is 18 years, 11.33 days. This means that the previous eclipse was in 2017 - 18 = 1999. It occured 11.33 days earlier which puts the date as August 11, 1999. The eclipse occurs 1/3 of a day ealier or 1/3 of the way around the world in an easterly direction. The previous eclipse in the same Saros is the famous August 11, 1999 eclipse that passed through central Europe and was seen by millions. (Note: if you add 6585.32 days to August 11,1999 you get August 21,2017.) If you advance 18 years, 11.33 days the next eclipse in this Saros will occur September 2, 2035 in the Far East.

Eclipses in Canada?

Unless you are willing to travel the prospects for a total eclipse in Canada are not great! Over the next 100 years you will have

Pics of the August 2017 eclipse