Astronomy

What are the seasons caused by?

the axis of the Earth being tilted 23.5%

How long does it take for the Earth to revolve around the sun?

365.25 days (one year)

True or false: the seasons are caused by how close Earth is to the sun?

false

What changes every year?

the angle of the incoming sunlight

What do different places receive?

more or less direct sunlight

True or false: the higher the angle of sunlight, the warmer the temperature?

true

Autumn/spring

1. the Earth’s axis is at 90% away from the sun

2. the Earth will have 12 hours of day and night on the Northern and Southern Hemispheres

Summer

when the Earth’s axis points toward the sun

winter

When the Earth’s axis points away from the sun

solstice

day of the most or fewest daylight hours each year

summer solstice

first day of summer (June 21 or 22)=most daylight

winter solstice

first day of winter (December 21 or 22)=least daylight

equinox

day of equal hours of daylight and night

vernal (spring) equinox

first day of spring (March 20 or 21)

autumnal (fall) equinox

first day of fall (September 22 or 23)

How does the Moon compare to the Earth?

it is about ¼ the size of Earth and has a lower density

Descriptions of the Moon

1. no atmosphere

2. many surface craters

3. gravity is about 1/6 as much as Earth

How far away is the Moon from the Earth?

an average of 238,855 miles away from the Earth (the equivalent of 30 Earths)

The impact theory

1. currently accepted theory about the Moon’s formation

2. as the solar system was still forming, Earth was hit by a Mars-sized object

First step of the impact theory

debris from the impact orbited the Earth

Second step of the impact theory

gravity pulled the debris together to form the moon. The more dense materials were pulled into the Earth and the less dense materials made up the Moon

Third step of the impact theory

impacts and rotation kept the surface of the Moon molten until about 3 billion years ago. Today, the surface is changed only by the impacts (and an occasional golf ball)

Where does the Moon rise and set?

rises in the East and sets in the West

When does the Earth rotate on its axis?

once every 24 hours, but the Moon is also moving along its orbit at the same time

What is the result of the Moon moving ahead of the Earth?

the Earth has the spin for an extra 50 minutes everyday to catch up to it. This is why the Moon rises 50 minutes later each day and appears at different times throughout the month

Describe the time it takes for the Moon to rotate and revolve and return to the same point in reference to the sun in 29.5 days (synodic month)

rotates and revolves in 27.3 days (sidereal month)

True or false: we only see one side of the Moon?

true

Why do we see changes to the half of the Moon facing the Earth?

due to the Moon’s revolution around Earth (called the phases of the Moon)

New Moon

Moon is between Earth and Sun (cannot be seen!)

1st and 3rd (last) Quarter Moon

Earth, Moon, and Sun form a 90 degree angle. Half of the half (thus, a quarter) of the Moon can be seen

Full Moon

Earth is between the Moon and the Sun. Entire face of Moon is seen

Gibbous Moons

most, but not all, of the Moons lighted side is seen

Crescent Moons

a small part of Moon’s lighted side is seen

Waxing (“wax-on”-right)

new to full visible part of the Moon is getting larger

Waning (“left is leaving”)

full to new visible part of Moon is getting smaller