Eclipses and Tides

Entry 9

What is an Eclipse?

When Earth or the Moon

temporarily blocks the sunlight

from reaching the other.

Two Types of Eclipses-

1. Solar Eclipse- Moon comes between Sun and Earth and casts a shadow on Earth.

2. Lunar Eclipse- Earth comes between the Sun’s light and the moon and blocks the light from the moon.

Shadows of Eclipses-

1. Umbra- Darkest part of a shadow.

2. Penumbra- lighter portion of a shadow.

Solar Eclipse

A solar eclipse can only occur when the moon is in its “new moon” phase.

Total and Partial Solar Eclipses

Lunar Eclipse

A lunar eclipse can only occur when the moon

is in its “full moon” phase.

Total Lunar Eclipse Lunar eclipses occur because of

the moon’s tilted orbit and only occur a couple times in a year

Feb 20, 2008- partial starts 8:43

total starts 10:00

What is a tide?

The rise and fall of the sea level. Caused by the gravitational pull of the Sun

and the Moon. There are 2 high tides and 2 low tides daily.

Affect of Gravity on tides- The moon’s gravity exerts a strong pull on the

Earth causes the water to bulge outward at places. The bulges of water are high tides & non-bulges

are low tides.

Spring Tides-

When there is the greatest difference between high and low tides (high-highs and low-lows).

Occurs when moon is in a straight line with sun and Earth= New moon and Full moon.

Neap Tides-

When there is the little difference between high and low tides (almost equal).

Occurs when moon is at 90° with sun and Earth= 1st and 3rd quarter.