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 the Earth. A solar eclipse can occur only when the Moon is close enough to the ecliptic plane during 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 (29.53059 days). 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 the Earth) and the centres of the Sun and the 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 100 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 last only a maximum of 7.5 minutes for any one location and is usually less). People referred to as eclipse chasers or umbraphiles will travel even to remote locations to observe or witness predicted central solar eclipses
A solar eclipse is a spectacular sight and a rare astronomical event. Each one is only visible from a limited area.
There are 4 different types of solar eclipses. How much of the Sun’s disk is eclipsed, the eclipse magnitude, depends on which part of the Moon’s shadow falls on Earth.
- Partial solar eclipsesoccur when the Moon only partially obscures the Sun’s disk and casts only its penumbra on the Earth.
- Annular solar eclipsestake place when the Moon’s disk is not big enough to cover the entire disk of the Sun, and the Sun’s outer edges remain visible to form a ring of fire in the sky. An annular eclipse of the Sun takes place when the Moon is near apogee, and the Moon’s antumbra falls on Earth.
- Total solar eclipseshappen when the Moon completely covers the Sun, and it can only take place when the Moon is near perigee, the point of the Moon’s orbit closest to Earth. You can only see a total solar eclipse if you’re in the path where the Moon casts its darkest shadow, the umbra.
- Hybrid Solar Eclipses, also known as annular-total eclipses, are the rarest type. They occur when the same eclipse changes from an annularto a total solar eclipse, and/or vice versa, along the eclipse’s path.
Solar eclipses are only visible from within the area on the Earth where the Moon’s shadow falls, and the closer you are to the centre of the shadow’s path, the bigger the eclipse looks.
Solar eclipses are usually named for their darkest, or maximum, point. The exception is the hybrid eclipse.
The darkest point of solar eclipse is only visible from a small area. In most places and for most of the duration, total, annular, and hybrid eclipses look like a partial solar eclipse.
For a solar eclipse to take place, the Sun, the Moon, and Earth must be aligned in a perfect or near-perfect straight line. A rough alignment of the three bodies happens every lunar month, at the New Moon.