What are lunar What are lunar eclipses?eclipses?

Shadows are…Shadows are…

When you walk outside on a When you walk outside on a sunny day, you can see your sunny day, you can see your shadow. shadow.

A A shadowshadow is formed when an is formed when an object blocks a light source. A object blocks a light source. A shadow has two parts.shadow has two parts.

Parts of a Shadow…Parts of a Shadow… The center of a shadow is very The center of a shadow is very dark. The dark part of a shadow dark. The dark part of a shadow is called the is called the umbraumbra..

Around the outside of a shadow, Around the outside of a shadow, you will see a lighter part. The you will see a lighter part. The light part of a shadow is called light part of a shadow is called the the penumbrapenumbra..

Penumbra

Penumbra

Umbra

Eclipse of the MoonEclipse of the Moon

As the moon revolves around As the moon revolves around Earth it usually passes above or Earth it usually passes above or below Earth’s shadow.below Earth’s shadow.

Sometimes the moon passes Sometimes the moon passes directly through Earth’s shadow.directly through Earth’s shadow.

As a result, sunlight is blocked As a result, sunlight is blocked from reaching the moon. from reaching the moon.

Eclipse of the MoonEclipse of the Moon When the sunlight is blocked When the sunlight is blocked

from the moon, a from the moon, a lunar eclipselunar eclipse occurs.occurs.

A lunar eclipse can occur only A lunar eclipse can occur only during the full-moon phase.during the full-moon phase.

Eclipses occur when the Sun, the Earth Eclipses occur when the Sun, the Earth and the Moon all lie along a straight line.and the Moon all lie along a straight line.

The Moon’s orbit is tilted The Moon’s orbit is tilted 55oo with respect to with respect to

the ecliptic so there are only two times a the ecliptic so there are only two times a year when the paths overlap.year when the paths overlap.

Total or Partial EclipsesTotal or Partial Eclipses Sometimes the moon moves Sometimes the moon moves

entirely into the Earth’s umbra. entirely into the Earth’s umbra. When this happens, all of the sun’s When this happens, all of the sun’s

light is blocked. light is blocked. The entire face of the moon The entire face of the moon

darkens. darkens. This is called a total lunar eclipse.This is called a total lunar eclipse.

Total or Partial EclipsesTotal or Partial Eclipses Sometimes, only part of the moon Sometimes, only part of the moon

moves into Earth’s umbra. moves into Earth’s umbra. Sunlight can still reach the moon.Sunlight can still reach the moon. As a result, only part of the moon As a result, only part of the moon

darkens.darkens. This is called a partial lunar This is called a partial lunar

eclipse.eclipse.

Progress of a Lunar eclipse. The red glow is refracted red light from the Earth’s atmosphere, much like the red glow we see before sunrise and after sunset.

Ticket Out the DoorTicket Out the Door

The dark part of a shadow is the _______.The dark part of a shadow is the _______. A lunar eclipse occurs when Earth is A lunar eclipse occurs when Earth is

between the _______ and the moon.between the _______ and the moon. A _______ lunar eclipse occurs when A _______ lunar eclipse occurs when

part of the moon is in Earth’s penumbra.part of the moon is in Earth’s penumbra. During a _______ eclipse, all of the moon During a _______ eclipse, all of the moon

is dark.is dark.