If We Say That a Galaxy Has a Lookback Time

question 129

Multiple Choice

If we say that a galaxy has a lookback time of 1 billion years, we mean that .

• A)its light traveled through space for 1 billion years to reach us
• B)it was 1 billion light- years away when the light left the galaxy
• C)it is now 1 billion light- years away
• D)it is 400 million years old

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Definitions:

Photoreceptors

These are specialized cells in organisms that respond to light, allowing for the perception of vision and light-related responses.

Proprioceptors

Proprioceptors are sensory receptors located in muscles, tendons, and joints that provide information about body position and movement, enhancing coordination.

Exteroceptors

Exteroceptors are sensory receptors that receive stimuli from the external environment, such as light, sound, and temperature, providing information about the external world.

Interoceptors

Sensory receptors located within the body's internal organs that provide information about the internal environment.