Solar Eclipse (Ring)
" Eclipse of the Sun " redirects here. For the film, see Eclipse of the Sun (film). For the Novel please see Eclipse of the Sun (Novel).
Definition:
a). A total solar eclipse occurs when the Moon completely covers the Sun's disk, as seen in this 1999 solar eclipse. Solar prominences can be seen along the limb (in red) as well as extensive coronal filaments.
b). An annular solar eclipse occurs when the Moon is too far away to completely cover the Sun's disk (May 20, 2012). During a partial solar eclipse, the Moon blocks only part of the Sun's disk (October 23, 2014).
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A Solar Eclipse (Ring) occurs when a portion of the Earth is engulfed in a shadow cast by the Moon which fully or partially blocks sunlight. This occurs when the Sun, Moon and Earth are aligned. Such alignment coincides with a new moon (syzygy) indicating the moon is closest to the ecliptic plane. In a total eclipse, the disk of the Sun is fully obscured by the Moon. In partial and annular eclipses, only part of the Sun is obscured.
If the Moon were in a perfectly circular orbit, a little closer to the Earth, and in the same orbital plane, there would be total solar eclipses every new moon. However, since the Moon's orbit is tilted at more than 5 degrees to the Earth's orbit around the Sun, its shadow usually misses Earth. A solar eclipse can only occur when the Moon is close enough to the ecliptic plane during a new moon. Special conditions must occur for the two events to coincide because the Moon's orbit crosses the ecliptic at its orbital nodes twice every draconic month (27.212220) days) while a new moon occurs one every synodic month (29.530587981) days. Solar (and lunar) eclipse seasons therefore happen only during eclipse seasons resulting in at least two, and up to five, solar eclipses each year; no more than two of which can be total eclipses.
Total eclipses are rare because the timing of the new moon within the eclipse season needs to be more exact for an alignment between the observer (On Earth) and the centers of the Sun and Moon. In addition, the elliptical orbit of the Moon often takes it far enough away from Earth that its apparent size is not large enough to block the Sun entirely. Total solar eclipses are rare at any particular location because totality exists only along a narrow path on the Earth's surface traced by the Moon's full shadow or umbra.
An eclipse is a natural phenomenon. However, in some ancient and modern cultures, solar eclipses were attributed to supernatural causes or regarded as bad omens. A total solar eclipse can be frightening to people who are unaware of its astronomical explanation, as the Sun seems to disappear during the day and the sky darkens in a matter of minutes.
Since looking directly at the Sun can lead to permanent eye damage or blindness, special eye protection or indirect viewing techniques are used when viewing a solar eclipse. It is technically safe to view only the total phase of a total solar eclipse with the unaided eye and without protection; however, this is a dangerous practice, as most people are not trained to recognize the phases of an eclipse, which can span over two hours while the total phase can only last a maximum of 7.5 minutes for any one location. People referred to as eclipse chasers or umbraphiles will travel to remote locations to observe or witness predicted central solar eclipses.
Types of Eclipse Solar (Ring):
There are four types of solar eclipses (Ring):
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- A total eclipse when the dark silhouette of the Moon completely obscures the intensely bright light of the Sun, allowing the much fainter solar corona to be visible. During any one eclipse, totality occurs at best only in a narrow track on the surface at best only in a narrow track on the surface of Earth. This narrow track is called the path of totality.
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2.An annular eclipse occurs when the Sun and Moon are exactly in line with the Earth, but the apparent size of the Moon is smaller than that of the Sun. Hence the Sun appears as a very bright ring, or annulus, surrounding the dark disk of the Moon.
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- 3.A hybrid eclipse (also called annular/total eclipse) shifts between a total and annular eclipse. At certain points on the surface of Earth, it appears as a total eclipse, whereas at other points it appears as annular. Hybrid eclipses are comparatively rare.
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- 4.A partial eclipse occurs when the Sun and Moon are not exactly in line with the Earth and the Moon only partially obscures the Sun. This phenomenon can usually be seen from a large part of the Earth outside of the track of an annular or total eclipse. However, some eclipses can only be seen as a partial eclipse, because the umbra passes above the Earth's polar regions and never intersects the Earth's surface. Partial eclipses are virtually unnoticeable in terms of the Sun's brightness, as it takes well over 90% coverage to notice any darkening at all. Even at 99%, it would be no darker than civil twilight. Of course, partial eclipses (and partial stages of other eclipses) can be observed if one is viewing the Sun through a darkening filter (which should always be used for safety).
The Sun's distance from Earth is about 400 times the Moon's distance, and the Sun's diameter is about 400 times the Moon's diameter. Because these ratios are approximately the same, the Sun and the Moon as seen from Earth appear to be approximately the same size: about 0.5 degree of arc in angular measure.
A separate category of solar eclipses is that of the Sun being occluded by a body other than the Earth's Moon, as can be observed at points in space away from the Earth's Moon, as can be observed at points in space away from the Earth's surface. Two examples are when the crew of Apollo 12 observed the Earth eclipse the Sun in 1969 and when the Cassini probe observed Saturn eclipsing the Sun in 2006.
The Moon's orbit around the Earth is slightly elliptical, as is the Earth's orbit around the Sun. The apparent sizes of the Sun and Moon therefore vary. The magnitude of an eclipse is the ratio of the apparent size of the Moon to the apparent size of the Sun during an eclipse. An eclipse that occurs when the Moon is near its closest distance to Earth (i.e., near its perigee) can be a total eclipse because the Moon will appear to be large enough to completely cover the Sun's bright disk or photosphere; a total eclipse has a magnitude greater than or equal to 1.000. Conversely, an eclipse that occurs when the Moon is near its farthest distance from Earth (i.e., near its apogee) can only be an annular eclipse because the Moon will appear to be slightly smaller than the Sun; the magnitude of an annular eclipse is less than 1.
A hybrid eclipse occurs when the magnitude of an eclipse changes during the event from less to greater than one, so the eclipse appears to be total at locations nearer the midpoint, and annular at other locations nearer the beginning and end, since the sides of the Earth are slightly further away from the Moon. These eclipses are extremely short in their duration at any point, at most just a few seconds at any location with just a few kilometres of the centerline of the path. Like a focal point, the width and duration of totality and annularity are near zero at the points where the changes between the two occur.
Because the Earth's orbit around the Sun is also elliptical, the Earth's distance from the Sun similarly varies throughout the year. This affects the apparent size of the Sun in the same way, but not as much as does the Moon's varying distance from Earth. When Earth approaches its farthest distance from the Sun in early July, a total eclipse is somewhat more likely, whereas conditions favour an annular eclipse when Earth approaches its closest distance to the Sun in early January.
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Terminology of Central Eclipse:
Central eclipse is often used as a generic term for a total, annular, or hybrid eclipse. This is, however, not completely correct: the definition of a central eclipse is an eclipse during which the central line of the umbra touches the Earth's surface. It is possible, though extremely rare, that part of the umbra intersects with the Earth (thus creating an annular or total eclipse), but not its central line. This is then called a non-central total or annular eclipse. The last (umbral yet) non-central solar eclipse was on April 29, 2014. This was an annular eclipse. The next non-central total solar eclipse will be on April 9, 2043.
The phases observed during a total eclipe are called:
- First Contact - When the Moon's limb (edge) is exactly tangential to the Sun's limb.
- Second Contact - Starting with Baily's Beads (Caused by light shining through valleys on the Moon's surface) and the diamond ring effect. Almost the entire disk is covered.
- Totality - The Moon obscures the entire disk of the Sun and only the solar corona is visible.
- Third Contact - When the first bright light becomes visible and the Moon's shadow is moving away from the observer. Again a diamond ring may be observed.
- Fourth Contact - When the trailing edge of the Moon ceases to overlap with the solar disk and the eclipse ends.
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Duration of Eclipse Solar (Ring):
The following factors determine the duration of a total solar eclipse (in order of decreasing importance):
- The Earth being very near aphelion (furthest away from the Sun in its elliptical orbit, making its angular diameter nearly as small as possible).
- The midpoint of the eclipse being very close to the Earth's equator, where the rotational velocity is greatest.
- The vector of the eclipse path at the midpoint of the eclipse aligning with the vector of the Earth's rotation (i.e. not diagonal but due east).
- The Moon being almost exactly at perigee (Making its angular diameter as large as possible).
- The midpoint of the eclipse being near the subsolar point (The part of the Earth closest to the Sun).
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Historical of Eclipse Solar (Ring):
Historical eclipses (Ring) are a very valuable resource for historians, in that they allow a few historical events to be dated precisely, from which other dates ancient calendars may be deduced. A solar eclipse of June 17, 763 BC mentioned in an Assyrian text is important for the chronology of the ancient Near East. There have been other claims to date earlier eclipses. The Book of Joshua 10:13 describes an event that a group of University of Cambridge scholars concluded to be the annular solar eclipse that occurred on 30 October 1207 BC. The Chinese king Zhong Kang supposedly beheaded two astronomers, Hsi and Ho, who failed to predict an eclipse 4,000 years ago. Perhaps the earliest still-unproven claim is that of archaeologist Bruce Masse, who putatively links an eclipse that occurred on May 10, 2807 BC with a possible meteor impact in the Indian Ocean on the basis of several ancient flood myths that mention a total solar eclipse.
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Eclipse And Transits:
In principle, the simultaneous occurrence of a solar eclipse and a transit of a planet is possible. But these events are extremely rare because of their short durations. The next anticipated simultaneous occurrence of a solar eclipse and a transit of Mercury will be on July 5, 6757, and a solar eclipse and a transit of Venus is expected on April 5, 15232.
More common, but still infrequent, is a conjunction of a planet (especially, but not only, Mercury or Venus) at the time of a total solar eclipse, in which event the planet will be visible very near the eclipsed Sun, when without the eclipse it would have been lost in the Sun's glare. At one time, some scientists hypothesized that there may be a planet (often given the name Vulcan) even closer to the Sun than Mercury; the only way to confirm its existence would have been to observe it in transit or during a total solar eclipse. No such planet was ever found, and general relatively has since explained the observations that led astronomers to suggest that Vulcan might exist.
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EarthShine:
During a total solar eclipse, the Moon's shadow covers only a small faction of the Earth. The Earth continues to receive at least 92 percent of the amount of sunlight it receives without an eclipse - more if the penumbra of the Moon's shadow partly misses the Earth. Seen from the Moon, the Earth during a total solar eclipse is mostly brilliantly illuminated, with only a small dark patch showing the Moon's shadow. The brilliantly-lit Earth reflects a lot of light to the Moon. If the corona of the eclipsed Sun were not present, the Moon, illuminated by earth light, would be easily visible from Earth. This would be essentially the same as the earthshine which can frequently be seen when the Moon's phase is a narrow crescent. In reality, the corona, though much less brilliant than the Sun's photosphere, is much brighter than the Moon illuminated by earthlight. Therefore, by contrast, the Moon during a total solar eclipse appears to be black, with the corona surrounding it.
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Impact of Eclipse Solar (Ring):
The Solar Eclipse of March 20, 2015, was the first occurrence of an eclipse estimated to potentially have a significant impact on the power system, with the electricity sector taking measures to mitigate any impact. The continental Europe and Great Britain synchronous areas were estimated to have about 90 gigawatts of solar power and it was estimated that production would temporarily decrease by up to 34 GW compared to a clear sky day. The temperature may decrease by 3 Celcius, and wind power potentially decreases as winds are reduced by 0.7 m/s.
In addition to the drop in light level and air temperature, animals change their behavior during totality. For example, birds and squirrels return to their nests and crickets chirp.
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Recent And Forthcoming of Eclipse Solar (Ring):
Eclipses only occur in the eclipse season, when the Sun is close to either the ascending or descending node of the Moon. Each eclipse is separated by one, five or six lunations (synodic months), and the midpoint of each season is separated by 173.3 days, which is the mean time for the Sun to travel from one node to the next. The period is a little less than half a calendar year because the lunar nodes slowly regress. Because 223 synodic months is roughly equal to 239 anomalistic months and 242 draconic months, eclipses with similar geometry recur 223 synodic months (about 6,585.3 days) part. This period (18 years 11.3 days) is a saros. Because 223 synodic months is not identical to 239 anomalistic months or 242 draconic months, saros cycles do not endlessly repeat. Each cycle begins with the Moon's shadow crossing the Earth near the north or south pole, and subsequent events progress toward the other pole until the Moon's shadow misses the Earth and the series ends. Saros cycles are numbered; currently, cycles 117 to 156 are active. The last solar eclipse occured on July 2, 2019. It was a total solar eclipse visible from South America.
@ Jackie San
