Earth, Sun, Moon Relationships

​Earth, Sun, Moon Relationships

Multiple Choice

What is Kepler's first law?

• The orbit of a planet is a perfect circle
• The orbit of a planet is a straight line
• The orbit of a planet is a spiral
• The orbit of a planet is an ellipse with the Sun at one of the two foci.

​Once upon a time there was a dude.

His name was Ptolemy.

He stared at the sky a lot.

From his observations, he deduced that everything HAS to revolve around the Earth right?

​We call this the geocentric model.

​Geo=earth

Centric=center

​This assumption was based on phenomena known as retrograde motion.

​This is the "apparent westward motion of planets with respect to the stars".

​Basically Mars was doing a loop-di-loop from our point of view.

​
When really we were doing this...

Multiple Choice

What is the apparent westward motion of planets in relation to the stars?

• Upward motion
• Sideways motion
• Forward motion
• Retrograde motion

Multiple Choice

Why do we still learn about Ptolemy if he was wrong about the geocentric model?

• Because he was the first astronomer to propose the geocentric model
• Because his model was proven to be correct in modern times
• Because he was the only astronomer of his time
• Ptolemy's work laid the foundation for future astronomers and his model was influential for centuries.

​SO...we were pretty much riding the geocentric train for a while...

...about 1,500 years to be exact...

​Then we had this guy...

​He's Copernicus.

​see..?

​Based on previous theories established by Aristarchus (310-230 BCE), Copernicus maintained that Earth spins on an axis and revolves around the Sun.

So other planets such as Mars must also follow suit.

​Two forces maintain this heliocentric model.

​Inertia

​Gravity

Multiple Choice

Who originally presented the idea of a heliocentric model?

• Isaac Newton
• Galileo Galilei
• Johannes Kepler
• Aristarchus

Multiple Choice

How is the heliocentric model different from the geocentric model?

• The heliocentric model states that the planets revolve around the Moon.
• The heliocentric model places the Earth at the center of the solar system.
• The heliocentric model places the Sun at the center of the solar system.
• The heliocentric model believes that the Sun moves around the Earth.

​Let's start some new vocab.

​Rotation:

The spinning of a planet on its axis

​There are two types of days based on this rotation.

​Mean Solar Day

The 24 hrs we as a society call "1 day".

​Sidereal Day

The actual time it takes to complete one full 360 degree rotation.

​24 hours

​23 hours 56 min 4 sec

Multiple Choice

What is the sidereal day and how does it differ from the mean solar day?

• The sidereal day is the time it takes for a specific star to return to the same position in the sky.
• The sidereal day is the time it takes for the Earth to complete one full rotation on its axis.
• The sidereal day is the time it takes for the Moon to complete one full orbit around the Earth.
• The sidereal day is the time it takes for the Sun to return to the same position in the sky.

​Revolution

​That orbiting thing planets do around the sun.

​In this orbit...

​Keep in mind the root Helios...

​Perihelion

Aphelion

​Peri-around

​Ap-away from

​So then why is it so cold when we are closest to the Sun?

• ​As the Earth orbits, different parts of Earth are exposed to the sun.

  • the Earth tilts on an axis

​This tilt is at 23.5 degrees.

Summer occurs in the hemisphere that has the most sun exposure.

Multiple Choice

What season is it in the United states when the Sun shines on the southern hemisphere?

• Winter
• Summer
• Autumn
• Spring

As the Earth orbits around the Sun, so does the moon around the Earth.

​As the moon orbits around Earth, this creates what we know as tides.

​Tides: as water moves around the Earth.



This is influenced by the position of the moon around the Earth.

​Tides: as water moves around the Earth.



This is influenced by the position of the moon around the Earth.

​Primary force comes from the Moon's gravity

​Tides: as water moves around the Earth.



This is influenced by the position of the moon around the Earth.

​Primary force comes from the Moon's gravity

​The sun's gravity is the secondary force

​This bulging and moving creates a tidal range.

Multiple Choice

What is the primary force acting on Earth's tidal bulge?

• Gravitational pull of the Sun
• Centrifugal force from Earth's rotation
• Wind patterns across the ocean
• Gravitational pull of the Moon

​2 types of tidal ranges

​Spring tide

Neap tide

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​There are three types of tidal patterns.

Multiple Choice

What causes the Earth's seasons?

• the earths rotation speed

• Earth's axial tilt

• The Earth's shape

• The distance from the sun

Multiple Choice

What is the angle of the Earth's axis tilt?

• 23.5 degrees

• 30 degrees

• 15 degrees

• 45 degrees

Multiple Choice

Why are the equator and poles at different temperatures?

• The angle of the axial tilt.

• Because of the Earth's rotation speed.

• Earth's distance from the sun.

• The difference in sun exposure.

Multiple Choice

What happens when the Earth's axis is tilted toward the Sun?

• It's summertime in the southern hemisphere.

• It's summertime in the northern hemisphere.

• It's wintertime in the southern hemisphere.

• It's wintertime in the northern hemisphere.

Multiple Choice

What is the reason for the different seasons in the northern hemisphere and southern hemisphere?

• The shape of the Earth.

• The Earth's rotation speed.

• The angle of the Earth's axial tilt.

• The distance from the Earth to the Sun.