Classwork Sun Moon Earth System



Classwork Sun Moon Earth System Name ____________________ Date____

Daily Motions

Sun, Moon, planets, and stars rise in the East and set in West

These daily motions occur as a result of Earth’s rotation

How do we know Earth is rotating? Two ways:

1. Foucault pendulum swings in a constant direction; due to Earth’s rotation, it appears that the pendulum shifts; can see this when place pegs on floor and pendulum knocks pegs down

2. Flowing air and water diverted from north-south direction to east-west direction

Annual Motions

We know Earth rotates around the sun because:

1. See weather changes, 2. day length changes, 3. temperature changes as result of Earth’s motion around the Sun

ecliptic - The plane in which Earth orbits the Sun

Effects of Earth’s Tilt

Earth’s axis tilted to the ecliptic at 23.5 degrees

As Earth orbits Sun, orientation of the Earth’s axis remains fixed so at one point the northern hemisphere is tilted toward the sun, and at another point 6 months later, the northern hemisphere is tilted away from the Sun.

Solstices -

During summer solstice, Sun is at highest altitude in the sky (June 21); number of daylight hours at maximum

Summer solstice-Sun is directly overhead at Tropic of Cancer (23.5N latitude)

During winter solstice, the sun is at its lowest altitude in the sky (Dec 21); number of daylight hours at minimum; Sun is directly overhead at Tropic of Capricorn (23.5S latitude)

Equinoxes

Two positions Earth is not pointed at Sun; as result both hemispheres receive same amount of sunlight and Sun is directly overhead at the equator

Called autumnal and vernal equinox (equinox means “equal nights”)

Tides

Moon affects Earth by the formation of tides

Moon’s gravity pulls on Earth along imaginary line connecting Earth and the Moon that creates bulges of ocean water on both the near and far sides of the Earth

Earth’s rotation contributes to tide formation

As Earth rotates, these bulges align with the Moon

Person at shoreline on Earth’s surface would see ocean level rise every 12 hours

Sun’s gravitational effect (about ½ of the Moon’s) not as strong as the Moon’s because further away from the Earth

When Sun and Moon are aligned, see stronger tides because effects are combined

These higher tides are called spring tides and they are high when Moon is nearest Earth and Earth is nearest the Sun

Lower than normal tides, or neap tides, occur when the Moon is at a right angle to the Sun-Earth line

Solar Eclipses

A solar eclipse occurs when the Moon passes directly between the Sun and the Earth and blocks our view of the Sun

When the Moon perfectly blocks out the Sun’s disk, we only see the dim, gaseous outer layers of the Sun; this is called a total solar eclipse

Partial solar eclipse seen when the Moon blocks a portion of the Sun’s disk

The difference between a partial and total solar eclipse can be explained by the fact that the Moon casts a shadow on Earth.

Shadow consists of two regions: inner portion called the umbra that doesn’t receive direct sunlight, and an outer portion called the penumbra that receives some sunlight

People who witness eclipse from the umbra (inner portion) see a total solar eclipse

People who witness eclipse from the penumbra (outer portion) see a partial solar eclipse

Umbral shadow very small (~270 km), so total solar eclipse visible from small portion of Earth

Solar Eclipse

Effects of Orbits

Only when the Moon intersects the Earth’s ecliptic in line with the Sun and Earth does a solar eclipse occur

Closest point in Moon’s orbit around Earth is called the perigee

Farthest point in Moon’s orbit around the Earth is the apogee

When Moon is near apogee, appears smaller from Earth and can’t block out Sun entirely

When Moon is near perigee, appears larger on Earth and can block out Sun entirely

Lunar Eclipse

Lunar eclipse occurs when Moon passes through Earth’s shadow

Can only happen during a full moon when the Moon is in the opposite direction from the Sun

Earth has two parts to its shadow like the moon: umbral and penumbral

When entire Moon is in the Earth’s umbral shadow, you can see a total lunar eclipse

Total lunar eclipse lasts approximately 2 hours; can see a Moon during this phase because sunlight that has passed near Earth has been refracted by Earth’s atmosphere

Gives light a reddish appearance

Periodicity of Eclipses

Solar and lunar eclipses don’t occur every full moon because the Moon in orbit usually passes above or below the Sun as seen from Earth

Solar and lunar eclipses occur in almost equal numbers, with slightly more lunar eclipses

Maximum number of combined eclipses that can occur per year is seven; this won’t happen again until 2038

Assignment:

Using your notes and/or your textbook, make flash cards to show each of the following (draw it on one side, identify it on the other side):

Earth’s tilt

Ecliptic

Autumnal Equinox

Vernal Equinox

Apogee and perigee

Solar eclipse

Lunar eclipse

Moon surface features

EM spectrum (radio waves …. Gamma waves)

Latitude and longitude lines; equator and Prime Meridian

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