Imagine Living 10,000 Years Ago. You Are Gathering Nuts and Berries When Without Warning

EclipsesName ______

Core _____

Imagine living 10,000 years ago. You are gathering nuts and berries when without warning, the Sun disappears. The darkness lasts only a short time, and the Sun soon returns to full brightness. You know something strange has happened, but you don’t know why or how. It will be almost 8,000 years before anyone can explain what you just experienced.

The event just described was a total sola eclipse. Today, most people know what causes eclipses. What causes the day to become night and then change back into day?

What causes an eclipse?

The revolution of the Moon around Earth causes eclipses. Eclipses take place when Earth blocks light from reaching the Moon, or when the Moon blocks light from reaching a part of Earth. Sometimes, during a new moon, the Moon’s shadow falls on Earth. This causes a solar eclipse. During a full moon, Earth may cast a shadow on the Moon. This causes a lunar eclipse.

An eclipse can take place only when the Sun, the Moon and Earth are lined up perfectly. Because the Moon’s orbit is not in the same plane as Earth’s orbit around the Sun, lunar eclipses take place only a few

times each year.

What is an eclipse of the Sun?

A solar eclipse occurs when the Moon moves directly between the Sun and Earth and casts its shadow over part of Earth. A solar eclipse is shown in the figure below. Depending on where you are on Earth, you may be in a total eclipse or a partial eclipse. Only a small area of Earth is part of the total solar eclipse during the eclipse event.

The darkest portion of the Moon’s shadow on Earth is called the umbra. A person standing within the umbra experiences a total solar eclipse. During a total solar eclipse, the only part of the sun that is visible is a white glow around the edge of the eclipsing Moon.

Surrounding the umbra is a lighter shadow on Earth’s surface. This lighter shadow is called the penumbra. Those who are standing in the penumbra experience a partial solar eclipse.

WARNING: Regardless of which eclipse you view, never look directly at the Sun.

Label the umbra, penumbra, Sun, Earth and Moon of the solar eclipse.

What is an eclipse of the Moon?

When Earth moves directly between the Sun and the Moon and its shadow falls on the Moon, a lunar eclipse occurs. A lunar eclipse begins when the Moon moves into Earth’s penumbra. As the Moon continues to move, it enters Earth’s umbra, and you can see a curved shadow on the moon’s surface.

As the moon moves completely into Earth’s umbra, it goes dark. This is a total lunar eclipse. Sometimes sunlight bent through Earth’s atmosphere will cause the eclipsed Moon to have a reddish appearance.

Label all parts of the lunar eclipse.

During which lunar phase do eclipses occur?

Lunar eclipses do not happen every month. Lunar eclipses happen only during the full moon phase.

A total lunar eclipse can be seen by anyone on the nighttime side of Earth as long as the Moon is not hidden by clouds. Only a few people get to witness a total solar eclipse, however. Only those in the small area where the Moon’s umbra strikes Earth can witness it.