Can we see solar eclipse today
A solar eclipse 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 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.SEE VIDEO BY TOPIC: 5 ways to safely view the 2017 total solar eclipse
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A solar eclipse 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 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 Solar and lunar eclipses 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 safe to view only the total phase of a total solar eclipse with the unaided eye and without protection. This practice must be undertaken carefully, though the extreme fading of the solar brightness by a factor of over times in the last minute before totality makes it obvious when totality has begun and it is for that extreme variation and the view of the solar corona that leads people to travel to the zone of totality the partial phases span over two hours while the total phase can only last a maximum of 7.
People referred to as eclipse chasers or umbraphiles will travel even to remote locations to observe or witness predicted central solar eclipses. The Sun's distance from Earth is about times the Moon's distance, and the Sun's diameter is about 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. 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 surface. Two examples are when the crew of Apollo 12 observed the Earth eclipse the Sun in and when the Cassini probe observed Saturn eclipsing the Sun in 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. An eclipse that occurs when the Moon is near its closest distance to Earth i. Conversely, an eclipse that occurs when the Moon is near its farthest distance from Earth i. 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 narrow in their path width and relatively short in their duration at any point compared with fully total eclipses; the April 20 hybrid eclipse's totality is over a minute in duration at various points along the path of totality. 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. Central eclipse is often used as a generic term for a total, annular, or hybrid eclipse. 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, This was an annular eclipse. The next non-central total solar eclipse will be on April 9, The phases observed during a total eclipse are called: . The diagrams to the right show the alignment of the Sun, Moon, and Earth during a solar eclipse.
The dark gray region between the Moon and Earth is the umbra , where the Sun is completely obscured by the Moon. The small area where the umbra touches Earth's surface is where a total eclipse can be seen.
The larger light gray area is the penumbra , in which a partial eclipse can be seen. An observer in the antumbra , the area of shadow beyond the umbra, will see an annular eclipse.
The Moon's orbit around the Earth is inclined at an angle of just over 5 degrees to the plane of the Earth's orbit around the Sun the ecliptic. Because of this, at the time of a new moon, the Moon will usually pass to the north or south of the Sun. A solar eclipse can occur only when new moon occurs close to one of the points known as nodes where the Moon's orbit crosses the ecliptic.
As noted above, the Moon's orbit is also elliptical. Therefore, the Moon's apparent size varies with its distance from the Earth, and it is this effect that leads to the difference between total and annular eclipses.
The distance of the Earth from the Sun also varies during the year, but this is a smaller effect. It is only when the Moon is closer to the Earth than average near its perigee that a total eclipse occurs.
The Moon orbits the Earth in approximately This is known as the sidereal month. However, during one sidereal month, Earth has revolved part way around the Sun, making the average time between one new moon and the next longer than the sidereal month: it is approximately This is known as the synodic month and corresponds to what is commonly called the lunar month. The Moon crosses from south to north of the ecliptic at its ascending node , and vice versa at its descending node. This regression means that the time between each passage of the Moon through the ascending node is slightly shorter than the sidereal month.
This period is called the nodical or draconic month. Finally, the Moon's perigee is moving forwards or precessing in its orbit and makes a complete circuit in 8. The time between one perigee and the next is slightly longer than the sidereal month and known as the anomalistic month. The Moon's orbit intersects with the ecliptic at the two nodes that are degrees apart.
Therefore, the new moon occurs close to the nodes at two periods of the year approximately six months Sometimes the new moon occurs close enough to a node during two consecutive months to eclipse the Sun on both occasions in two partial eclipses.
This means that, in any given year, there will always be at least two solar eclipses, and there can be as many as five.
Eclipses can occur only when the Sun is within about 15 to 18 degrees of a node, 10 to 12 degrees for central eclipses. This is referred to as an eclipse limit, and is given in ranges because the apparent sizes and speeds of the Sun and Moon vary throughout the year. In the time it takes for the Moon to return to a node draconic month , the apparent position of the Sun has moved about 29 degrees, relative to the nodes.
During a central eclipse, the Moon's umbra or antumbra, in the case of an annular eclipse moves rapidly from west to east across the Earth.
The width of the track of a central eclipse varies according to the relative apparent diameters of the Sun and Moon. But at what longitudes on the Earth's surface the shadow will fall, is a function of the Earth's rotation, and on how much that rotation has slowed down over time. This means that, although it is possible to predict that there will be a total eclipse on a certain date in the far future, it is not possible to predict in the far future exactly at what longitudes that eclipse will be total.
The following factors determine the duration of a total solar eclipse in order of decreasing importance :  . The longest eclipse that has been calculated thus far is the eclipse of July 16, with a maximum duration of 7 minutes 29 seconds over northern Guyana. Total solar eclipses are rare events. Although they occur somewhere on Earth every 18 months on average,  it is estimated that they recur at any given place only once every to years, on average.
This value changes over the millennia and is currently decreasing. Observers aboard a Concorde supersonic aircraft were able to stretch totality for this eclipse to about 74 minutes by flying along the path of the Moon's umbra. It is possible to predict other eclipses using eclipse cycles. The saros is probably the best known and one of the most accurate. A saros lasts 6, A saros series always starts with a partial eclipse near one of Earth's polar regions, then shifts over the globe through a series of annular or total eclipses, and ends with a partial eclipse at the opposite polar region.
A saros series lasts to years and 69 to 87 eclipses, with about 40 to 60 of them being central. Between two and five solar eclipses occur every year, with at least one per eclipse season.
Since the Gregorian calendar was instituted in , years that have had five solar eclipses were , , , , , and The next occurrence will be Total solar eclipses are seen on Earth because of a fortuitous combination of circumstances. Even on Earth, the diversity of eclipses familiar to people today is a temporary on a geological time scale phenomenon.
Hundreds of millions of years in the past, the Moon was closer to the Earth and therefore apparently larger, so every solar eclipse was total or partial, and there were no annular eclipses. Due to tidal acceleration , the orbit of the Moon around the Earth becomes approximately 3.
Millions of years in the future, the Moon will be too far away to fully occlude the Sun, and no total eclipses will occur. In the same timeframe, the Sun may become brighter, making it appear larger in size. Historical eclipses are a very valuable resource for historians, in that they allow a few historical events to be dated precisely, from which other dates and ancient calendars may be deduced. The Book of Joshua describes an event that a group of University of Cambridge scholars concluded to be the annular solar eclipse that occurred on 30 October BC.
Eclipses have been interpreted as omens , or portents. Both sides put down their weapons and declared peace as a result of the eclipse. Chinese records of eclipses begin at around BC. Attempts have been made to establish the exact date of Good Friday by assuming that the darkness described at Jesus's crucifixion was a solar eclipse. This research has not yielded conclusive results,   and Good Friday is recorded as being at Passover , which is held at the time of a full moon.
Further, the darkness lasted from the sixth hour to the ninth, or three hours, which is much, much longer than the eight-minute upper limit for any solar eclipse's totality.
The What: Eye Safety
The first thing to remember about observing an eclipse is safety. A solar eclipse is potentially dangerous, however, because viewing a solar eclipse involves looking at the Sun, which can damage your eyesight. A solar eclipse can be viewed safely with the naked eye only during the few brief seconds or minutes of a total solar eclipse , when the Sun itself is completely obscured by the Moon. Partial eclipses , annular eclipses , and the partial phases of total solar eclipses are never safe to watch without taking special precautions. Failure to use appropriate filtration may result in permanent eye damage or blindness.
A solar eclipse will occur across most of the United States on April 8, , including a small band of total solar eclipse stretching from east to west across much of the continent. Before you do, please take the time to learn about the dangers to your vision and how to protect your eyes from injury during the eclipse. Never look directly at the sun during a solar eclipse except during the very brief time the sun is in total eclipse; and even then, with caution. Looking directly at the sun can cause permanent damage to your eyes. A solar eclipse occurs when the moon moves between the sun and the earth.
You can also watch with our free Android and iOS app! Be sure to prepare for viewing solar eclipses live: use these tips and techniques to get a clear view without injuring your eyes. This is probably the most important part of this website. Never view the Sun with the naked eye or by looking through optical devices such as binoculars or telescopes! This is critical! You may have taken a magnifying glass out into the sun and burned leaves with it. So understand this: you have a lens just like that in your eye. This literally burns your eye, causing permanent eye damage or blindness. In additional, there are no pain sensors inside your eye—so you won't even know it's happening! If you are now completely terrified about looking at the Sun, good!
Why is it dangerous to look at the solar eclipse directly specially at that moment?
By Anne Buckle and Aparna Kher. One of the easiest ways to safely watch a solar eclipse is to use 2 sheets of cardboard and make your own simple pinhole projector. Never look directly at the Sun without proper eye protection. You can seriously hurt your eyes and even go blind.
Make a Projector to Safely See a Solar Eclipse
Solar eclipse guide 2020: When, where & how to see them