ECLIPSES
SCIENCE STARTER:
Draw a diagram to answer this question:
Draw the position of the Moon, Sun, and
Earth during a SOLAR ECLIPSE! Label
EARTH, SUN, MOON!
Set up page 22 in your ISN---ECLIPSES
LOOK at my ISN if you are confused!!!
The Tides:
Lesson 2.3
Mrs. Gianelos
Grade 8 Science
• Tides caused by pull of Moon’s gravity on Earth
• High tide –
– Side facing Moon and side away from Moon
– Every 12 hours, 25 ½ minutes
• Low tide –
– On sides of Earth
What are tides?
• They are the regular rising and falling
of the ocean.
• HIGH TIDE: the water moves way
up the beach
• LOW TIDE: you see lots of shore,
since the water moves way out
• There are 2 high tides and 2 low tides
a day. The tides change every 6
hours.
What causes the tides?
Near Tide
(Type of High Tide)
Low Tide
Opposite Tide
(Type of High Tide)
When and where?
• The Earth rotates once every 24 hours which
means that the places on the Earth where HIGH
and LOW occur tides are always changing. The
diagram below shows where HIGH and LOW
tides will be 6 hours after the earlier diagram.
C
B
D
A
What is a Spring Tide?
• The Sun also has a gravitational effect on the sea.
Although the Sun is larger than the Moon, it is
further away from the Earth, which means that it
has less effect on our tides. Twice a month,
during the new moon and the full moon, the
Moon and the Sun are in line with the Earth and
so they pull together. This causes very high high
tides and very low low tides called SPRING
tides.
What is a Neap Tide?
• Twice a month, during the first and third (or
last) quarters, the Sun and Moon are at right
angles to each other, and so their pulls sort of
cancel each other out, and are not as great. This
causes much smaller tides. These are called
NEAP tides.
Solar and Lunar Eclipses
Eclipse:
The total or partial
obscuring of one celestial
body by another/ shadow
makes the Sun or Moon
seem to grow dark
The obscuration can be either
• One celestial body blocking
the view to the other:
– Solar eclipse---Moon
blocking Earth’s
view to the Sun
• One celestial body is in the
shadow of another:
– Lunar eclipse--Moon is in the
shadow of the Earth
Lunar eclipse image from http://www.mreclipse.com
Lunar Eclipses
• Moon moves into
Earth’s shadow –
this shadow darkens
the Moon
• About 2-3 per year
• Last up to 4 hours
Solar Eclipses
• Moon moves between
Earth and Sun
• Moon casts a shadow
on part of the Earth
• Total eclipses rare –
only once every 360
years from one
location!
Solar eclipses
• Solar eclipses occur when
the shadow of the Moon
falls on the surface of
Earth
– Only people in the shadow
can see the eclipse.
• Solar eclipses can be
partial, annular, or total.
• Solar eclipses can occur
only at new moon.
Click on the image to start animation
What Causes Eclipse?
• The Earth and Moon cast shadows.
• When either passes through the other’s shadow, we have an eclipse.
• Because the Sun is an extended bright object, there are two different
regions of the shadow:
– Penumbra is spreading cone of lighter shadow
– Umbra is completely dark/ darkest part of shadow
Click on the image to start animation
Lunar eclipses
• Lunar eclipses happens
when the Moon passes
through the shadow of the
Earth
– Everybody on the night
side of Earth can see the
lunar eclipse.
• Lunar eclipses can be
partial, penumbral, or
total.
• Lunar eclipses can occur
only at full moon.
Click on the image to start animation
Solar Eclipse Forecast
Solar eclipses from 2004 to 2030
Knowing the
orbit of the
Earth and the
Moon, we
can now
calculate the
time and path
of solar
eclipses with
great
accuracy.
Back to Eclipse Path
Eclipses: Summary
• The parties involved: Sun, Moon, and
Earth
• Solar eclipse happens when the Moon is
between the Earth and the Sun.
• The size and distance of the Moon need to
be just right for us to see total eclipse.
• Lunar eclipse happens when Earth is
between the Moon and the Sun.
• Solar eclipses occur when the Moon
passes directly between the Earth and the
Sun.