What is an eclipse?

An eclipse takes place when the sun, moon and earth line up and the sun's light is obscured.

There are two major types of eclipses,

Solar Eclipses and Lunar Eclipses.

Types of Shadow

The umbra is the darkest part of the shadow where the sun’s light is completely blocked. Within the umbra the viewer sees a total or annular solar eclipse.

The penumbra is the part of the shadow when the sun’s light is only partially blocked. Viewers within the penumbra will see a partial eclipse.

The antumbra is the part of the shadow that extends beyond the umbra. This causes only partial blockage of the sun. Viewers within the antumbra would see an annular eclipse where the moon appears smaller than the sun.

Solar Eclipses

Solar eclipses occur when the moon is positioned between the sun and Earth. This blocks the sun's light during the day and can only occur with a new moon.

There are four different types of solar eclipses.

Full or Total Solar Eclipse is when the sun is completely blocked by the moon. This is possible because the moon passes close to the earth in its elliptical orbit. These are the most rare type of eclipse because it can only be viewed from within the umbra of the shadow which is usually approximately a 100 x 10,000 mile area (160 x 16,000 km). The visible ora around a total eclipse is called the corona, meaning crown in Latin.

There are 3 special sights during a total solar eclipse.

Bailey’s Beads are the bead like blobs that appear around the moon as a result of the mountains and valleys on the moon’s surface. This happens 10-15 seconds before totality.

Diamond Ring Effect occurs when the Bailey’s Beads have disappeared except for one big blob. This occurs seconds before totality.

Corona are the rays of light that can faintly be seen around the ring of the moon. This is not the face of the sun, but rather the aura of plasma surrounding the sun. It can only be viewed during a total eclipse.

Partial Solar Eclipses occur when the moon is between the Earth and sun but the three do not perfectly align. Only part of the sun is blocked by the moon. The distance of the moon from the earth is not relevant, so these are more common. This can be witnessed from within the pentumbra shadow of a full or annular eclipse or when the umbra does not reach Earth.

The above diagram shows an eclipse that

can only be seen as partial on earth.

Annular Solar Eclipses occur when the celestial bodies are perfectly aligned and the moon is in the center of the sun and a ring of sunlight is still visible. The name is derived from the Latin word 'annulus' meaning ring. The moon appears smaller than the sun because it is further from Earth in its elliptical orbit, called the apogee. The umbra is too short to reach earth, leaving the ring viewable in the antumbra.

A Hybrid Solar Eclipses is rare because it shifts from an annular to a total eclipse, then back to annular along its orbital path.

http://www.classzone.com/books/earth_science/terc/content/visualizations/es2505/es2505page01.cfm?chapter_no=25

Comparison of Solar Eclipse Types

Protect your eyes!

It is never a good idea to look directly at the sun and an eclipse is no exception. The UV radiation can burn your retinas. Therefore, precautions must be made. Solutions include wearing welder’s googles, using appropriate filters, or creating a pinhole projector.

Pinhole projectors can be easily made at home.

Myths and Superstitions

Throughout history and across cultures, solar eclipses have been the cause for legends, but they hold no scientific basis.

Hungry demons eating the sun:

Chinese - dragon

Vietnam - frog

Vikings - wolves

Greeks saw eclipses as a sign of angry Gods

Inuits believed the god of the Sun walked away from a fight with the moon god and the eclipse was the moon catching up with the sun.

Koreans thought magical dogs were trying to steal the sun.

Upcoming Solar Eclipses

Lunar Eclipses

Lunar Eclipses occur when Earth's shadow blocks the sun's light, which otherwise reflects off the moon. A lunar eclipse can occur only at full moon.

3 Types Of Lunar Eclipses

1. A total lunar eclipse is the most dramatic lunar eclipse. It occurs when the Earth's shadow completely covers the moon. Total lunar eclipses can happen only when the sun, Earth, and moon are perfectly lined up-anything less creates a partial eclipse or no eclipse at all.

3 Types Of Lunar Eclipses

2. A partial lunar eclipse occurs when the Earth moves between the Sun and Moon but the 3 celestial bodies do not form a perfectly straight line in space. When that happens, a small part of the Moon's surface is covered by the darkest, central part of the Earth's shadow, called the umbra.

3 Types Of Lunar Eclipses

3. A penumbral lunar eclipse occurs when the moon becomes completely immersed in the penumbral cone of the Earth without touching the umbra.