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