Earth's place in the universe

​Earth's place in the universe

• ​Actual motion is how objects actually move. For example, Earth rotates on its axis.

• Apparent motion is how objects appear to move. For example, due to Earth's rotation, the sun seems to rise and set each day.

• The geocentric model was later replaced by the heliocentric model. In this model, the sun is at the center of the universe.

• In reality, the sun is only at the center of our solar system, not the entire universe.

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​Key points:

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Multiple Choice

Many of the planets in our solar system are visible in Earth’s night sky. Over time, these planets are seen to travel slowly eastward relative to the stars. During certain periods, however, the planets seem to reverse direction, traveling instead to the west. This change in direction is known as retrograde motion.

What is retrograde motion an example of?

Choose 1 answer:

• actual motion

• apparent motion

Multiple Choice

What causes the sun to rise every morning?

Choose 1 answer:

• the sun revolving around Earth

• Earth revolving around the sun

• the sun rotating on its axis

• Earth rotating on its axis

Multiple Choice

What defines an Earth year?

Choose 1 answer:

• the time required for Earth to complete one spin on its axis

• the time required for Earth to complete one trip around the sun

• the time required for the sun to complete one trip around Earth

Multiple Select

What is true about the geocentric model?

Choose 2 answers:

• It was replaced by the heliocentric model.

• It shows the sun as the center of the universe.

• It was based on the apparent motion of the sun and stars.