SOLAR ECLIPSE

A solar eclipse happens when the sun casts the moon’s shadow on the earth.

The moon makes one orbit around the earth every 27.3 days.

A solar eclipse occurs during new moon phase if the moon is lined up directly between the sun and the earth.

This does not happen every month because the plane of the moon’s orbit is tilted about five degrees. Usually the moon is above or below the direct line between the earth and the sun. https://spaceplace.nasa.gov

When alignment does occur, the shadow of the moon is cast on the earth. Image taken from the Russian Mir spacecraft

There are two major parts of the moon’s shadow There are two major parts of the moon’s shadow. The penumbra is the lighter outer part of the shadow, and the umbra is the dark inner part of the shadow.

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There are three types of solar eclipses: total, partial, and annular.

TOTAL SOLAR ECLIPSE

A solar eclipse is said to be total when the moon completely blocks the light of the sun.

A total solar eclipse is possible because while the sun is about 400 times larger than the moon, the moon is about 400 times closer than the sun.

For this reason both objects appear to be about the same size in the sky, and the moon is therefore able to block out the sun. http://astronomy.swin.edu.au/cosmos/A/Angular+Diameter

A total solar eclipse is visible from the umbra of the moon’s shadow. http://www.cnn.com/2017/05/12/us/solar-eclipse-2017/

The track of the moon’s dark shadow across the earth is called the path of totality. It is about 100 miles wide and 10,000 miles long.

THE PROGRESSION OF A TOTAL SOLAR ECLIPSE

First Contact (C1) – the moon begins to cover the sun

It takes about 1.5 hours for the moon to completely cover up the sun.

Just before totality, the last rays of sunlight shine through mountains and valleys on the edge of the moon creating specks of light called Baily’s Beads. The beads were named after Francis Baily, the astronomer who explained this phenomenon in 1836. http://www.alsonwongastro.com/2009.htm

The last bead coupled with the ring created by the appearance of the sun’s corona gives the look of a “Diamond Ring.” http://news.xinhuanet.com

Second Contact (C2) – totality - the sun is covered completely moon

During totality, the sun’s corona becomes visible During totality, the sun’s corona becomes visible. It is a layer of very hot gas surrounding the sun that streams out from the sun in a pattern created by the sun’s magnetic field. http://www.astroalert.su/files/img_0298_.jpg

Third Contact (C3) – the first portion of the sun is uncovered moon

As totality ends, the second diamond ring appears. http://news.xinhuanet.com

It is followed by another view of Baily’s Beads. https://eclipse2017.nasa.gov/baileys-beads-effect

Fourth Contact (C4) – the entire sun is uncovered moon

PARTIAL SOLAR ECLIPSE

A partial solar eclipse is visible from the penumbra of the moon’s shadow. http://www.cnn.com/2017/05/12/us/solar-eclipse-2017/

During a partial solar eclipse, only part of the sun is blocked by the moon.

The drop in the sun’s light level is usually not enough to be noticed.

http://www.hko.gov.hk/gts/event/astro-photo201012_e.htm

http://www.nowhabersham.com/partial-solar-eclipse-thursday/

www.scienceabc.com

eclipse.aas.org

A partial solar eclipse can be viewed on each side of the path of totality during a total solar eclipse.

ANNULAR SOLAR ECLIPSE

During an annular solar eclipse, the moon is in direct alignment between the sun and the earth. However, the moon is too far away from earth for its umbra to reach the earth.

At the maximum phase of the eclipse, the moon covers the center of the sun, and the sun looks like a very bright ring around the moon. http://www.air-and-space.com

These photos were taken before, during, and after maximum phase of an annular eclipse. From http://sunearthday.nasa.gov/2006/multimedia/gal_010.php; photos taken by Fred Espenak

In conclusion, click on the link below to view an animation depicting all three types of solar eclipses. http://www.classzone.com/books/earth_science/terc/content/visualizations/es2505/es2505page01.cfm?chapter_no=visualization