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Solar Eclipses

Solar Eclipses

solar eclipse corona
Image of the solar corona taken during the 2008 total eclipse (click to enlarge).
© 2008 Miloslav Druckmüller, Peter Aniol, Vojtech Rušin.
Reproduced with permission.

caution sign CAUTION: Never look directly at the Sun!
Never look at the Sun through binoculars or telescope unless you have the proper filters!

How to observe a solar eclipse

2009 Eclipse News | Watch the Eclipse on the Web |
2009 Eclipse Path | 2009 Eclipse Images | Classroom Activities |
More about Eclipses | For SID Users | The August 2008 Eclipse

A solar eclipse occurs when the Moon, during its monthly trip around the Earth, happens to line up exactly between the Earth and the Sun, so that it casts a shadow on the Earth. But because of the Sun's large diameter, the shadow consists of two regions. The innermost cone of total darkness is called the umbra (latin for "shadow"), and it is projected in the center. Anyone in this central area will observe the total eclipse, because the Sun will be temporarily obscured by the Moon. The outer shadow is partially illuminated by the Sun, and is called the penumbra. Anyone in this region will see the partial eclipse, since the Sun is only partially obscured by the Moon. (Unfortunately, the terms "umbra" and "penumbra" are also used to describe regions of sunspots (see the glossary) so be careful to avoid confusion!)

eclipse diagram
(Image credit: Norm Sleep)

The glory of a solar eclipse comes from the dramatic view of the Sun's corona, or outer atmosphere, which we can see only when the brilliant solar disk is blocked by the Moon. The corona is not just light shining from around the disk. It is actually the outermost layer of the solar atmosphere. Although the gas is very sparse, it is extraordinarily hot (800,000 to 3,000,000 K), even hotter than the surface of the Sun! The corona shows up as pearly white streamers, and their shape is determined by the Sun's current magnetic fields. Thus every eclipse will be unique and beautiful in its own way.

If an eclipse occurs when the Moon lines up between the Earth and the Sun, shouldn't there be an eclipse every month? Solar eclipses do occur at New Moon, but not at every New Moon. Most often the Moon passes a little higher or a little lower than the Sun. There is a solar eclipse once or twice a year, when the Moon's and Sun's positions exactly line up.

How to observe a solar eclipse

When there is a solar eclipse, it is only visible from a small area of the Earth. It's unlikely that, during your lifetime, you will ever have a total solar eclipse right where you live. However, many people travel long ways to experience a total solar eclipse. Or, if you're lucky, you might be able to see a partial solar eclipse (one where the Moon doesn't quite cover all the Sun's disk) nearby someday.

You can safely observe a TOTALLY eclipsed Sun with your eyes. However, for observing the beginning and ending of an eclipse, or for a partial eclipse, you will need a pinhole camera, an appropriate type of welder's glass, or special Mylar glasses to observe the Sun safely.


The July 22, 2009 Solar Eclipse

2009 eclipse path
Image Credit: Dr. Andrew Sinclair. Source:
Eclipse Predictions by Fred Espenak, NASA/GSFC

News and Press Releases


Watch the July 22, 2009 Eclipse On the Web:

Exploratorium Webcast

Live Eclipse 2009 (Japan)

National Astronomical Observatory of the
Chinese Academy of Sciences


Images of the 22 July, 2009 Solar Eclipse

Eclipse Video Clips (

Gallery 1
Gallery 2
Gallery 3
Gallery 4
Gallery 5
Gallery 6
Gallery 7
Gallery 8

NASA's 3D animation
Satellite images of eclipse shadow
Magnetohydrodynamic prediction of the corona
Predictions of the coronal shape
Lunar limb profile

Other Web Sites on the July 2009 Eclipse

exploratorium eclipse logo The Exploratorium presents live online images and programs on the evening before as well as during the eclipse.

nasa logoThe NASA eclipse website

Description and some nice animations of the July 22 eclipse eclipse page


Solar Eclipse Activities

If you have a SID monitor, be sure to read:
The Ionosphere during a Total Solar Eclipse

sun icon First, try this solar eclipse modeling activity!

sun icon How Do Eclipses Occur?

Gives some background about eclipses and introduces a simple eclipse activity.

sun icon Eclipsing the Sun

A simple classroom demonstration from NASA

sun icon How can the little Moon hide the giant Sun?

Another eclipse demonstration

sun icon Observing Eclipses

Students who live in the path of the eclipse (partial or total) are invited to build their own pinhole camera or solar projector and make observations of the eclipse.

sun icon

This web site contains a lesson plan outline for learning about solar eclipses. Also be sure to check the learning section

sun icon Determining the Earth-Moon Distance

This web site explains the mathematics of solar eclipses (for middle school and high school students).

sun icon A total solar eclipse exercise for high school students


About Solar Eclipses

sun icon
The ultimate resource for eclipse photography. Contains basic information about eclipses and some nice image galleries of solar and lunar eclipses.

sun icon The Science of Eclipses An article from the ESA website.

sun icon On the nature of Solar and Lunar eclipses

sun icon Solar Eclipses (complete with animations)

sun icon Fred Espenak's solar eclipse path page. See predictions of future eclipse paths!

sun icon The 1919 Total Solar Eclipse and Einstein's General Relativity


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Last Modified July 2008.

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