Eclipses. The Sun and Moon occasionally line up so that we have an eclipse. Revolution of the moon causes eclipses. An eclipse is defined as an astronomical.

Eclipses

Eclipses

• The Sun and Moon occasionally line up so that we have an eclipse.

• Revolution of the moon causes eclipses.

• An eclipse is defined as an astronomical event that occurs when one celestial object moves into the shadow of another, partially or fully obscuring it from view.

• Can only occur when the sun, the moon, and the Earth are lined up perfectly.

Two Types of Eclipses:

Solar Eclipse

Lunar Eclipse

Solar Eclipse• When the moon travels directly between the Sun and the

Earth and casts a shadow on part of Earth (blocks the Sun’s light from the Earth).

• Only possible at New Moon.• Because Earth rotates, it will take only a few minutes to move

out of the Moon's shadow.

Moon blocks out sun

Two Types of Solar Eclipses:

Total Solar EclipsePartial Solar Eclipse

Total Solar Eclipse• Observers in the “umbra” shadow see a total eclipse

where the moon completely blocks the Sun.• Umbra – darkest portion of the moon’s shadow.

Total Solar Eclipse

• Total eclipses are rare! Only once every 360 years from one location.• The entire Earth does not see a total eclipse. It depends on where the umbra and penumbra fall on the Earth.

Partial Solar Eclipse• Observers in the “penumbra” shadow see a partial

eclipse where the moon blocks part of the Sun.

• Penumbra – lighter shadow on Earth’s surface.

Lunar Eclipse

Lunar Eclipse

• Occurs during a Full Moon when Earth’s shadow falls on the moon.

• Begins when the moon moves into Earth’s penumbra.

• As the moon continues to move, it enters Earth’s umbra and you see a curved shadow on the moon’s surface.

• When the moon moves completely into Earth’s umbra, the moon becomes dark red because light from the sun is refracted by the Earth’s atmosphere onto the moon.

• About 2-3 per year; last up to 4 hours

Why not eclipses every month?

• The moon’s orbit around the earth is tilted slightly compared to the Earth’s orbit around the Sun.

• All three objects must be lined up vertically for an eclipse to occur.

Earth

Moon

MoonPlane of earth’s orbit

Plane of lunar orbit