Earth, Moon, and Sun

Chapter 5Lesson 1-3

Earth in Space

Chapter 5Lesson 1Page 182

Earth in Space

• Earth moves in space in 2 major ways:

rotation and revolution

Rotation

• Axis- imaginary line that passes through Earth’s north and south pole

• Rotation-spinning of Earth on its axis• Rotation causes day and night• Rotates eastward• Takes about 24 hours

Revolution

• Revolution- movement of one object around another

• One revolution of Earth around the sun is called a year (that’s how long it takes)

• Earth is closest to the sun in January

Calendar

• Calendar- system of organizing time that defines beginning, length, and divisions of a year

• year= time it takes Earth to complete one orbit (revolution)

• Day=time it takes Earth to rotate on its axis (rotation)

• Months are based on the moon phases (though it has changed in modern times)

What Causes Seasons?

• Four distinct seasons: winter, spring, summer, & fall

• Temperature difference occur (more noticeable for places away from the equator)

• Sunlight directly hits at the equator and glances Earth at the poles which is why it is much warmer at the equator than the poles

Earth’s Tilted Access

• If it weren’t for the tilted axis temperatures on Earth would remain pretty constant year-round

• Earth has seasons because its axis is tilted as it revolves around the sun.

• Tilted at an angle of 23.5⁰ from vertical• So at different point of the year the north pole

it pointed towards the sun and 6 months later is it pointed away

Tilted Axis

• June- north end of Earth is pointed towards the sun, so the Northern Hemisphere has more daylight hours and is experiencing the summer (southern hemisphere would be in winter)

• December- North pole is pointed away so Southern Hemisphere is experiencing summer and Northern Hemisphere is experience winter

Solstices

• Sun appears farthest north of the equator once each year and farthest south once each year

• Each of these days are known as solstices• Sun appears:• Farthest North- Summer Solstice

Revolution

Sun appears Northern Hemisphere

Southern Hemisphere

We experience Day last

Farthest North Summer Winter Summer Longer(June 21)

Farthest South Winter Summer Winter Shorter (Dec 21)

Equinoxes

• Halfway between the solstices neither hemisphere is tilted towards that sun creating the equinoxes

• Equinox- noon sun directly overhead at the equator, rises due east, and sets due west

• Equal day and night (12 hours each)• Vernal (spring) March 21• Autumnal (fall) September 22

Phases and Eclipses

Chapter 5Lesson 2Page 190

Motions of the Moon

• Face on the moon is just shadows and light you see

• Same side of the moon always faces the Earth• The time it takes for the moon to rotate is the

same amount of time it take for it to revolve around Earth

• The changing relative positions of the moon, Earth, and sun cause the phases of the moon

Phases of the moon

• Half of the moon is almost always in sunlight, but since the moon orbits Earth, you see the moon from different angles

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

• The changes we see in the moon’s shape are called phases

Phases of the moon

• New Moon- side of moon facing Earth is not lit, so it appears dark

• As the moon revolves around Earth you see an increasing amount of the lit side of the moon until you see the whole lit side (full moon)

• The moon goes through a complete set of phases in about 29.5 days

Phases of the moon

Notice which phases show us the same amount of the lit side of the moon

What are Eclipses?

• Read page 193• Very rarely do the sun, Earth and moon line

up• Eclipse- when an object in space comes

between the sun and a third object, it casts a shadow on that object

• Two types:• Solar *Lunar

Solar Eclipses

• During a new moon, the moon lies between Earth and the sun

• Solar eclipse- occurs when the moon passes directly between Earth and the sun, blocking sunlight from Earth

• Umbra- darkest part of the moon’s shadow• Within the umbra, sunlight is completely blocked• Penumbra-shadow the is not completely dark

leaving part of the blocked solar body visible (larger than the umbra)

Lunar Eclipse

• Lunar Eclipse- at a full moon when Earth is directly between the moon and the sun

• During a lunar eclipse, Earth blocks sunlight from reaching the moon

• Only occurs during a full moon because it is closets to Earth’s shadow

• The moon is in Earth’s umbra- total• The moon in Earth’s penumbra- partial

Experiencing Total Eclipses

• Anyone that can see the moon during a lunar eclipse will experience the total lunar eclipse unlike the solar eclipse where you must be in the moon’s umbra to see a total solar eclipse