Eclipses

What is an eclipse?• The partial or total blocking of one

object in space by another• When the moon or Earth casts a

shadow on the other• It can happen in 2 ways: –When the Earth comes between the sun

and moon–When the moon comes between the sun

and Earth

How Does an Eclipse Happen?• The moon’s orbit around Earth is slightly

tilted when compared to Earth’s orbit around the sun.

How Does an Eclipse Happen?• The moon’s orbital plane goes below and

above the Earth’s orbital plane around the sun

Node

Node

How Does an Eclipse Happen?

• an eclipse can only occur when the Moon is in line with the Earth and Sun;

• an eclipse can only occur when the Moon is in (or near) the ecliptic plane

• it has to be at, or near, one of the two nodes, and that node has to be positioned in line with the Earth and the Sun.

How Does an Eclipse Happen?

Node Node

When do Solar Eclipses Occur?• During a new moon, the moon is

between Earth and the sun.• Most of the time, the moon’s orbit is

a little above or below where the sun is in the sky

When do Solar Eclipses Occur

• A solar eclipse happens when the moon passes DIRECTLY between Earth and the sun, blocking sunlight from Earth

• The moon’s shadow hits Earth• A solar eclipse happens when a new

moon blocks your view of the sun.

Total Solar Eclipse• During a solar eclipse, the moon’s

shadow hits Earth.• The shadow area is made of two parts,

the umbra and penumbra • The umbra is the darkest part of the

shadow and is cone shaped• The umbra is long enough that the

point of the cone can just reach a small part of Earth’s surface

Total Solar Eclipse• From any point in the umbra, the light from

the sun is completely blocked by the moon.• Only the people within the umbra

experience a total solar eclipse• During a total solar eclipse the sky is

completely dark, like night and the air gets cooler

• You can see stars and the corona around the sun

Total Solar Eclipse

Partial Solar Eclipse• During a solar eclipse, the moon’s

shadow hits earth and has two parts• The penumbra is larger and less dark

than the umbra• In the penumbra, part of the sun is

visible from Earth• People in the penumbra only see a

partial solar eclipse

Partial Solar Eclipse

When do Lunar Eclipses Occur?• During a full moon, Earth is between

the sun and moon• During most months the moon

moves near Earth’s shadow, but not quite into it.

When do Lunar Eclipses Occur?• A lunar eclipse happens during a full

moon when Earth is DIRECTLY between the moon and the sun, blocking sunlight from reaching the moon

• The moon is in Earth’s shadow and looks dim from Earth.

Total Lunar Eclipse• Earth’s shadow also has a umbra and

penumbra• When the moon is in Earth’s umbra you

see a total lunar eclipse• You can see the edge of Earth’s shadow on

the moon before and after a total lunar eclipse

• A total lunar eclipse can be seen anywhere on Earth that the moon is visible

Lunar Eclipse

Partial Lunar Eclipse• For most lunar eclipses, Earth, the

moon and sun are not quite in line• If they are not completely in line only

a partial lunar eclipse will happen• A partial lunar eclipse happens when

the moon passes partly into the umbra of Earth’s shadow

Partial Lunar Eclipse