Eclipses:Eclipses:

Shadow and LightShadow and Light

Which of the Following is True?Which of the Following is True?

1.1. An eclipse of the sun occurs when an An eclipse of the sun occurs when an invisible dragon eats the sun.invisible dragon eats the sun.

2.2. During eclipses, poisons drop from the During eclipses, poisons drop from the skysky

3.3. An eclipse is a sign that the world is An eclipse is a sign that the world is coming to an end. coming to an end.

4.4. None of thee above.None of thee above.

AnswerAnswer

None of thee above.None of thee above.

People from cultures all over the world People from cultures all over the world created these and other stories to explain created these and other stories to explain the mysterious disappearance of the sun the mysterious disappearance of the sun and moon from the sky. and moon from the sky.

Solar EclipseSolar Eclipse

A solar eclipse occurs when the Moon A solar eclipse occurs when the Moon comes directly between Earth and the comes directly between Earth and the Sun.Sun.

The key word is directly, because the The key word is directly, because the moon orbits the Earth every month, and moon orbits the Earth every month, and every month the moon casts a shadow. every month the moon casts a shadow.

Solar EclipsesSolar Eclipses

During a solar eclipse, the darkest part of During a solar eclipse, the darkest part of the Moon’s shadow cone, called the the Moon’s shadow cone, called the “umbra” is often only 250 kilometers in “umbra” is often only 250 kilometers in diameter. diameter. As the earth spins, different parts of it fall As the earth spins, different parts of it fall within the umbra.within the umbra.People who happen to be in the umbra People who happen to be in the umbra can see a total blocking of the Sun, or a can see a total blocking of the Sun, or a total solar eclipse. total solar eclipse.

Outside the UmbraOutside the Umbra

The moon blocks only part of the Sun and The moon blocks only part of the Sun and creates a partial Solar Eclipse.creates a partial Solar Eclipse.

A shadow is cast, but it isn’t as dark as the A shadow is cast, but it isn’t as dark as the umbra. This lighter part of the shadow umbra. This lighter part of the shadow cone is called the “preumbria.”cone is called the “preumbria.”

Lunar EclipseLunar Eclipse

In a Lunar Eclipse, Earth comes directly In a Lunar Eclipse, Earth comes directly between the Sun and Moon - placing the between the Sun and Moon - placing the Moon in Earth’s shadow. Moon in Earth’s shadow.

When the entire full moon falls within the When the entire full moon falls within the center of Earth’s umbra, we have a total center of Earth’s umbra, we have a total lunar eclipse. lunar eclipse.

Everyone on the night side of the Moon Everyone on the night side of the Moon can see the eclipse!can see the eclipse!

More on Lunar EclipsesMore on Lunar Eclipses

Depending on how much dust and how Depending on how much dust and how many clouds are in Earth’s atmosphere, many clouds are in Earth’s atmosphere, the moon will appear dark brown, red, the moon will appear dark brown, red, orange, or yellow.orange, or yellow.

Partial Lunar EclipsePartial Lunar Eclipse

A partial lunar eclipse occurs when only A partial lunar eclipse occurs when only part of the Moon passes through the part of the Moon passes through the Earth’s umbra.Earth’s umbra.

A penumrial lunar eclipse occurs when the A penumrial lunar eclipse occurs when the moon passes through only the lighter part moon passes through only the lighter part of Earth’s shadow cone. of Earth’s shadow cone.

Neither of these eclipses is as colorful as a Neither of these eclipses is as colorful as a lunar eclipse.lunar eclipse.

Safe Way to View a Solar EclipseSafe Way to View a Solar Eclipse

NEVERNEVER look through a telescope or look through a telescope or binoculars, or binoculars, or anyany optical aide or device optical aide or device that magnifies an image, at the Sun or a that magnifies an image, at the Sun or a

Solar Eclipse; this would cause Solar Eclipse; this would cause PERMANENT BLINDNESS INSTANTLY !PERMANENT BLINDNESS INSTANTLY !

Safety!Safety!

NONO filtering device, sunglasses, filtering device, sunglasses, photographic film or negatives, or photographic film or negatives, or

darkened or "smoked" glass or plastic, is darkened or "smoked" glass or plastic, is safe for looking at the Sun or a Solar safe for looking at the Sun or a Solar Eclipse, Eclipse, unlessunless it is SPECIFICALLY it is SPECIFICALLY DESIGNED FOR SOLAR ECLIPSE DESIGNED FOR SOLAR ECLIPSE

OBSERVING OBSERVING andand UNDAMAGED (i.e. UNDAMAGED (i.e. includes no pinholes or holes of any size) !includes no pinholes or holes of any size) !

Safety!Safety!

To safely view a Solar EclipseTo safely view a Solar Eclipse, prepare a box , prepare a box as shownas shown, with a pinhole (perhaps in aluminum , with a pinhole (perhaps in aluminum foil covering a larger hole in the box) at one end foil covering a larger hole in the box) at one end and a white sheet of paper at the other end, and a white sheet of paper at the other end, inside. inside.

Standing, Standing, with your back to the Sunwith your back to the Sun and your and your head inside the box, allow the Sun's light to head inside the box, allow the Sun's light to shine through the pinhole and observe a small shine through the pinhole and observe a small image of the Solar Eclipse on the white sheet of image of the Solar Eclipse on the white sheet of paper. paper.

AlternativesAlternatives

If you cannot find a box, you can also use two If you cannot find a box, you can also use two pieces of cardboard. pieces of cardboard. Place a pinhole in one piece of cardboard. Place a pinhole in one piece of cardboard. Standing with your back to the Sun, allow the Standing with your back to the Sun, allow the light from the eclipse to shine through the light from the eclipse to shine through the pinhole and project onto the second piece of pinhole and project onto the second piece of cardboard, where you will see a small image of cardboard, where you will see a small image of the solar eclipse. the solar eclipse. Again, Again, NEVERNEVER look through the pinhole at the look through the pinhole at the Sun or a Solar Eclipse; this could cause Sun or a Solar Eclipse; this could cause MAJOR MAJOR EYE DAMAGE and POSSIBLE BLINDNESS !EYE DAMAGE and POSSIBLE BLINDNESS !

Safety tips found at:Safety tips found at:

andrewcarnegie.tripod.com/solflyer2.htmandrewcarnegie.tripod.com/solflyer2.htm