Solar and Lunar Eclipses
What is an eclipse?
• An eclipse occurs any time something passes
in front of the Sun, blocking its light. This can
be the Earth or the Moon.
Is there more than 1 kind of eclipse?
• Lunar Eclipse- When the Earth casts a shadow
on the moon, causing the moon to go dark.
Earth comes between the Sun and the Moon
and casts a shadow on the Moon (Full Moon)
• Solar Eclipse- When the Moon casts a shadow
on the Earth, causing the sun to go dark.
The Moon comes between the Sun and Earth
and casts a shadow on part of Earth (New
Moon)
Lunar Eclipses
• The Earth moves between the Sun and the
Moon, blocking th Sun’s light, and causing the
moon to glow red.
• Umbra – The dark inner portion of the
shadow cone.
• Penumbra – the lighter outer portion of
the shadow.
Types of Solar Eclipses
• Total Solar Eclipse – can only occur if you are at the
exact spot within the moon’s umbra (which isn’t very
big).
• Partial Solar Eclipse – Visible is you are in the
penumbra of the shadow. Only some of the moon
will be shadowed.
• Annular Eclipse – occurs when the moon is farthest
from the Earth in its orbit. This makes the moon look
smaller, so during the eclipse you see an outer ring of
light from the Sun.
Total Solar Eclipse – can only occur if you are at the
exact spot within the moon’s umbra (which isn’t very
big).
Partial Solar Eclipse – Visible if you are in the penumbra
of the shadow. Only some of the moon will be
shadowed.
Annular Eclipse – occurs when the moon is farthest
from the Earth in its orbit. This makes the moon look
smaller, so during the eclipse you see an outer ring of
light from the Sun.
How often do Eclipses Happen?
• That depends!! Lunar Eclipses happen more
often than Solar Eclipses.
• Why? Well everyone who is experiencing
nighttime during a lunar eclipse can see it.
• But you have to be at the exact spot on Earth
to see a Solar Eclipse.
• The spot on Earth is so small, that the same
place only sees a Solar Eclipse every 350
years!!
Why Don’t We See Lunar
Eclipses More Often?
• Well, lunar eclipses don’t happen everyday
because the Moon’s orbit is tilted. So, during
most months, the Moon is above or below the
Earth.
Eclipse Seasons
• Syzygy- The times where the Moon, the Earth,
and the Sun line up perfectly for an eclipse.
Earth-Moon-Sun Relationship
Earthshine Project, BBSO (http://www.bbso.njit.edu/espr/fig10.html
Earth-Moon-Sun Relationship
Sphere – a round, three-dimensional object
whose surface at all points is the same
distance from its center
Axis – an imaginary line around which an object
spins
Earth-Moon-Sun Relationship
Rotation – the spinning of an object around its axis
Revolution – the orbiting of one object around another, like Earth revolving
around the sun
Ellipse – an elongated, closed curve; the shape of planetary orbits
Why do we have Seasons
They are caused by the tilt of Earth’s axis, 23½0
Equinox – when the noon sun is directly overhead at the equator, equal hours of daylight
and darkness
Solstice – when the noon sun is directly overhead at either 23½0N (Tropic of Cancer) or
23½0S (Tropic of Capricorn) latitude, coincides with the 1st day of summer or winter
Path of the Ecliptic
• The apparent path of the Sun across the sky.
In summer, the Sun's path is longest, and so
are the days.
In winter, the Sun's path is shortest, and so are
the days.
The Moon The Moon
•
2.
3.
4.
Earth’s only natural satellite
384,000km away, 1/6th the gravity of Earth
Noon temp. of 1300C, night temp. of -1750C
Surface features
1. Dark, flat plains called marias
2. Bright areas called highlands
MOOOON
The period of rotation equals the period of
revolution around the Earth
Apollo 11 put Neil Armstrong and Edwin “Buzz”
Aldrin on the moon on July 16th, 1969
Tides
- Caused by moon’s gravitational pull
- Spring Tide – the moon, Earth and sun align
- Neap Tide – when the moon, Earth and sun
form a right angle