The shadow of moon is not big enough to engulf the entire planet and limited to a certain area. This area changes during the course of the eclipse because of Moon and Earth are in constant motion. This is why solar eclipses seem to travel from one place to another.
When the moon does eclipse the sun, it produces two types of shadows on Earth.
1. Umbra: The umbral shadow is the relatively small in diameter point on Earth where an observer would see a total eclipse.
2. Penumbra: The penumbral shadow is the much larger area on Earth where an observer will see a partial eclipse. Here, the sun is not completely covered by the moon.
There are four types of solar eclipses. Depending on the location and specific geometry of the Sun, Earth and Moon system, one may experience one of four solar elcipses.
1. Total Eclipse
2. Partial Eclipse
3. Annular Eclipse
4. Hybrid Eclipse
1. Total Eclipse: happens when the moon completely covers the sun. You can only see a total solar eclipse if you are in the path where Moon casts its darkest shadow (Umbra). In total solar eclipse, the sun's outer atmosphere can be seen. There is a noticeable drop in both light level and temperature.
2. Partial Eclipse: occurs when the Moon passes in front of sun, off center and only a portion of the sun's disk is obscured. Here, observer is standing in the penumbral shadow of the Moon.
3. Annular Eclipse: happens when the Moon's disk is not big enough to cover the entire disk of the Sun, and the Sun's out edges remain visible around the dark disk of the moon to form a "ring of fire". In the annular eclipse, moon passes dead center in front of the sun but, because the moon's orbit is elliptical and so is sometimes closer and sometimes further from Earth, it appears too small to fully cover the disk of the sun.
4. Hybrid Eclipse: is a combination of total and annular eclipses. The eclipse begins as one type and ends as another. This is also known as annular-total eclipse and is the rarest type.
A total solar eclipse presents a rare opportunity to observe the corona and chromosphere, the two outer most layers of the sun’s atmosphere. Under normal circumstances, the bright yellow surface of the sun, called the photosphere, is the only feature we can observe. But during an eclipse, the moon blocks out that intense light, allowing scientists to observe the much dimmer solar atmosphere.
Corona:The corona is the outer atmosphere of the sun. It is made of tenuous gases and is normally hiding in plain sight, overwhelmed by the bright light of the sun’s photosphere. When the moon blocks the sun’s face during a total solar eclipse, the corona is revealed as a pearly-white halo around the sun. To study the corona, scientists use special instruments called coronagraphs, which mimic eclipses by using solid disks to block the sun's face. During a natural total eclipse, however, lower parts of the corona can be seen in a way that still cannot be completely replicated by current technology.Eclipse observations are important for understanding why the sun’s atmosphere is 1 million degrees hotter than its surface, as well as the process by which the sun sends out a constant stream of solar material and radiation, which cause changes in the nature of space and may impact spacecraft, communications systems, and orbiting astronauts.
Chromosphere:The chromosphere is a thin layer of the sun’s atmosphere that lies just below the corona, and about 3,100 miles (5,000 km) above the photosphere. It is only visible during total solar eclipses or with sophisticated telescopes. The word comes from chromo—or “color”—for the way this layer appears during eclipses: a thin, crimson ring around the edge of the sun, in contrast with the darkened moon and pearly-white corona. Protect your eyes: It is never safe to look directly at the Sun, eclipsed or otherwise, without any protective eyewear. The Sun's UV radiation can burn the retinas in your eyes leading to permanent damage or even blindness. During the short period when the moon completely obscures the sun- known as "period of totality"- it is safe to look directly, but it's crucial that you know when to take off and put back on your solar eclipse viewing glasses.
Protect your Eyes
It is never safe to look directly at the Sun, eclipsed or otherwise, without any protective eyewear. The Sun's UV radiation can burn the retinas in your eyes leading to permanent damage or even blindness. During the short period when the moon completely obscures the sun- known as "period of totality"- it is safe to look directly, but it's crucial that you know when to take off and put back on your solar eclipse viewing glasses.