Revolution/RotationDay/Night

Phases of the MoonSeasons

Astronomy = the study of the moon, stars, and other objects in space

Astronomers were interested in the movements of the sun and moon as they

seem to move across the sky.

Axis = the imaginary line that passes through Earth’s center and the North and South poles

Earth is tilted on its axis at an angle of 23.5 degrees.

Rotation= the Earth’s spinning on its axis

CFU: What is the degree of Earth’s tilt?

Earth’s rotation on its axis causes day and night. It takes Earth about 24 hours to rotate once on its axis.

It is day on the side of Earth facing the sun.

It is night on the side of Earth facing away from the sun.

CFU: Part of the Earth is always in daytime and part of the Earth is always in night time.

(True or False)

Earth also travels around the Sun. Its path around the sun is called its orbit. The shape of its orbit is a slightly flattened, oval shape.

The movement of one object around another is called revolution.

One complete revolution around the sun is called a year.

CFU: What is the movement of one object around another in space called?

What is one complete rotation of the Earth called?

What is one complete revolution of the Earth called?

The moon revolves around the Earth just as the Earth revolves around the sun.

The relative positions of the moon, Earth and the sun are always changing and cause the phases of the moon, eclipses and tides.

CFU: What causes phases of the Moon?

It takes the moon about 27.3 days to revolve around the Earth.

The moon does not produce the light you see, it reflects light from the sun.

The different shapes you see from Earth are called phases.

CFU: Does the moon produce it’s own light? Why does it look bright in the sky?

Since the moon revolves around the Earth you see the moon from different angles.

One side of the moon is almost always in sunlight.

The phase of the moon you see depends on how much of the sunlit side of the moon faces Earth.

CFU: How much of the moon is always in sunlight?

New Moon Waxing Crescent First Quarter Waxing Gibbous Full Moon Waning Gibbous Third Quarter Waning Crescent

The sun lights the side of the moon facing away from Earth. The side of the moon that faces Earth is dark.

You see more and more of the lighted side of the moon.

You see half of the lighted side of the moon.

The moon continues to wax. The moon is called Gibbous.

You see the whole lighted side of the moon.

The fraction of the lighted side of the moon that you see gets smaller each day.

You can see half of the moon’s lighted side.

You see a crescent again.

On rare occasions, the moon completely blocks the sun.

When the moon’s shadow hits Earth or the Earth’s shadow hits the moon, an eclipse occurs.

An eclipse occurs when an object in space comes between the sun and a third object.

CFU: What is an eclipse?

Solar eclipse Lunar eclipse

Occurs when the moon passes between Earth and the sun, blocking the sunlight from reaching Earth.

Happens only during new moon phase.

Occurs only at full moon when Earth is directly between the moon and the sun.

Earth blocks sunlight from reaching the moon and the moon looks dark.

CFU: What is the difference between a solar and lunareclipse?

Its ok to look at the sun during a partial solar eclipse but not during a total solar eclipse.

False

Its not ok to look during a partial lunar eclipse.

The force of gravity pulls the moon and Earth toward each other.

Tides occur because of differences in how much the moon pulls on different parts of the Earth.

There are 2 high tides and 2 low tides on Earth at any given time.

Most places have four distinct seasons: winter, spring, summer, and autumn.

If Earth’s axis were straight up and down relative to the sun, temperatures in any given place would remain the same year round.

Earth has seasons because its axis is tilted and moves around the sun.

As Earth revolves around the sun, its axis is tilted away from the sun for part of the year and toward the sun for part of the year.

When the North End of Earth’s axis is tilted toward the sun, the Northern Hemisphere has summer.

At the same time, the South End is tilted away from the sun and the Southern Hemisphere is experiencing winter.

Summer and Winter are not affected by changes in Earth’s distance from the sun.

How is Earth’s axis tilted when the Northern Hemisphere has summer?

Occurs when the noon sun is overhead at either 23.5 degrees north (summer) at the Tropic of Cancer and 23.5 degrees south (winter) at the Tropic of Capricorn.

Summer solstice is around June 21st and is the longest day of the year.

Winter solstice is around December 21st and is the shortest day of the year.

Northern and Southern Hemispheres experience Winter and Summer Solstices at opposite times of year.

The southern and northern hemispheres experience the summer solstice on the same exact day.

Halfway between the solstices, neither hemisphere is tilted toward or away from the sun.

This occurs only 2 days a year and is known as an equinox. (September 21st and March 21st)

Equinox means “equal night” and during an equinox, the lengths of nighttime and daytime are about the same.

CFU: What is the difference between a solstice and an equinox?