Tides and Eclipses, Lecture notes of Astronomy

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Tides and Eclipses

Tides

• The tides are the rising and falling of

the ocean surface as a result of the

gravitational pull of the moon

and the Sun on the earth.

• The Moon plays a bigger role than the

Sun because it is closer.

Role of the Sun

• The sun also has a gravitational pull on

the earth.

• When the sun is lined up with the moon and the earth, it “helps” the moon pull on the earth,

and the tides become more extreme.

• When the sun is not lined up with the moon and

the earth, it partially cancels out the pull of the

moon, and the tides are less extreme.

Spring Tides

• Sun, earth and moon are lined up.
• Higher high tide, Lower low tide. Regular Tide Level Tide Level during Spring Tides

Occurrence of Neap and Spring Tides

• Spring tides occur when sun, moon and earth

are lined up: Full

Moon and New

Moon.

Neap Tides occur

when the sun and moon pull in opposite

directions: First

Quarter and Last

Quarter.

Eclipses

• There are two types of eclipses:
  • Solar Eclipse- When the moon lines up exactly in between the sun and the earth.
  • It blocks out the sun so we can’t see it.
  • Lunar Eclipse- When the earth lines up exactly in between the moon and the sun, and prevents sunlight from reaching the moon.
  • Or, another way to say it is the moon moves into the shadow of the earth.

Solar Eclipse

Lunar Eclipse

• Occurs when the moon is a Full Moon and the earth, moon and sun are exactly lined up. Sun Earth Moon