Notes - Moon, Tides, & Seasons

Earth in Space The Earth spins on an imaginary line called the axis that passes from the North Pole to the South Pole. The spinning of Earth on its axis is called rotation, and this causes day and night. It takes Earth about 24 hours to rotate once.

Earth in Space Earth orbiting around the Sun is called revolution. Earth completes one revolution every 365 ¼ days or 12 moon cycles. Earth’s orbit is a slightly flattened circle, and it varies every 100,000 years in shape.

Earth in Space

The Reason for the Season Earth has seasons because its axis is tilted 23.5º away from the Sun for half the year, and toward the Sun for the other half.

The Reason for the Season When the North pole is tilted toward the Sun, the Northern hemisphere has summer (June, July, & August). During these months the Southern hemisphere has winter because they are tilted away from the Sun.

The Reason for the Season

The Reason for the Season Two days a year, the noon sun is directly overhead at 23.5º North or South – solstice days. Halfway between solstice days, at noon the sun is directly overhead at the equator – equinox days (equal day & equal night).

Motions of the Moon The moon is about ¼ the diameter of Earth The moon revolves around Earth about once every 27.3 days The same side of the moon always faces Earth

Phases of the Moon Different shapes we see are the phases of the moon The phase depends on how much of the sunlit side of the moon faces Earth

Phases of the Moon From new moon to full moon, you see an increasing amount of the lighted side New First Quarter (right half lit up) Full Third Quarter (left half lit up) new first quarter full third / last quarter

Eclipses Eclipses happen when the moon’s shadow hits Earth when Earth’s shadow hits the moon Eclipses happen when an object in space comes between the sun and a 3rd object, and casts a shadow on that object

Solar Eclipses (SUN is blocked) Moon passes between Earth & the sun The moon’s shadow hits Earth Umbra = darkest part of the moon’s shadow (only people who live in the umbra see a total solar eclipse) Penumbra = less dark, but larger shadow (people who live here see a partial eclipse)

Solar Eclipses

Lunar Eclipse (MOON is blocked) Occurs at a full moon when Earth is directly between the moon & sun Earth’s shadow falls on the moon Earth’s shadow has an umbra & penumbra

Lunar Eclipse

Tides Rise & fall of the ocean’s water every 12.5 hours Gravity pulls the moon and Earth toward each other Tides occur because of how much the moon pulls on different parts of Earth

Tides Earth rotates & the moon’s gravity pulls water toward the point on Earth’s surface closest to the moon The moon pulls least on the side of Earth farthest away 2 high tides a day & 2 low tides a day

Spring Tides Twice a month: the moon, Earth, & the sun are in a straight line, creating more gravity HIGH high tide & LOW low tide Called this because the water “springs” up & down the beach

Neap Tides Twice a month: the moon, Earth, & the sun are at right angles to each other LOW high tide & HIGH low tide

Spring & Neap Tides

1. The phase of the moon you see depends on 3.2 Pressure and the Buoyant Forces 1. The phase of the moon you see depends on A how much of the sunlit side of the moon faces Earth B where you are on Earth’s surface C how much of the moon’s surface is lit by the sun D whether or not an eclipse is occurring

2. From new moon phase to full moon phase you see 3.2 Pressure and the Buoyant Forces 2. From new moon phase to full moon phase you see A a decreasing amount of the lighted side of the moon B an increasing amount of the lighted side of the moon C the same amount of the lighted side of the moon. D more of the lighted side, then less of the lighted side of the moon.

3. For a solar eclipse to occur, 3.2 Pressure and the Buoyant Forces 3. For a solar eclipse to occur, A the sun must be directly between the Earth and the moon. B the moon must be directly behind Earth. C the moon must be directly between the Earth and the sun. D Earth must be directly between the sun and the moon.

4. During what phase can a lunar eclipse occur? A first quarter 3.2 Pressure and the Buoyant Forces 4. During what phase can a lunar eclipse occur? A first quarter B full moon C third quarter D new moon

A when the sun, Earth, and the moon are nearly in a line 3.2 Pressure and the Buoyant Forces 5. When are tides highest? A when the sun, Earth, and the moon are nearly in a line B during the moon’s first quarter phase C during the moon’s third quarter phase D when the moon is at a right angle to the sun

6. Tides are caused mainly by 3.2 Pressure and the Buoyant Forces 6. Tides are caused mainly by A Earth’s rotation on its axis, which causes water to move B differences in how much the sun pulls on different parts of Earth C differences in how much the moon pulls on different parts of Earth D strong winds blowing water onto coasts

7. How large is the moon compared to Earth? 3.2 Pressure and the Buoyant Forces 7. How large is the moon compared to Earth? A about the same diameter as Earth B about 1/8 the diameter of Earth C about 1/4 the diameter of Earth D about 1/2 the diameter of Earth

A first quarter and third quarter phase B new moon and full moon phase 3.2 Pressure and the Buoyant Forces 8. The amount of the lighted side of the moon you can see is the same during A first quarter and third quarter phase B new moon and full moon phase C new moon and first quarter phase D full moon and third quarter phase

9. When do neap tides occur? A at new moon 3.2 Pressure and the Buoyant Forces 9. When do neap tides occur? A at new moon B when the sun’s pull is in the same direction as the moon’s C at full moon D when the sun’s pull is at right angles to the moon’s

10. Earth’s axis is tilted ___. A 22º B 22.5º C 23.5º D 24º 3.2 Pressure and the Buoyant Forces 10. Earth’s axis is tilted ___. A 22º B 22.5º C 23.5º D 24º

3.2 Pressure and the Buoyant Forces 11. When the North pole is tilted toward the sun, the Northern hemisphere has A winter B spring C summer D fall