Page 164 - Science Course 3 (Book 2)

Mo12-L1b: How Does the Moon Affect Earth?

As the lit portion of the Moon becomes larger, the When Earth and the Moon are in line with the Sun,
Moon is waxing. the Sun’s gravitational pull adds to the Moon’s
gravitational pull.
The waxing phases are waxing crescent, f rst quarter,
and waxing gibbous. As a result, high tides are higher than usual.

Tides at this time are called spring tides. Spring tides
occur during full moon and new moon phases.

Spring Tides
High tides are higher than usual high tides.
Low tides are lower than usual low tides.

During the f rst and third quarter moons, the grav-
itational pull of the Moon is perpendicular to the
gravitational pull of the Sun.

High tides are lower than usual. Tides at these times
are called neap tides.

Neap Tides
High tides are lower than usual high tides.
Low tides are higher than usual low tides.

Tides

Tides are the periodic rise and fall of the oceans’ surfaces caused by the gravitational force between
Earth and the Moon and the Sun.
The Moon has more inf uence on tides than the Sun because it is closer to Earth than the Sun.

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